Sunday, April 27, 2:30 PM - 4:15 PM Hall B/C

Transcription

Sunday, April 27, 2:30 PM - 4:15 PM Hall B/C Poster Session Program Number/Board # Range: 885-899 / D715-D729
154. Imaging Retinal Disease and Visual Function Organizing Section: VI Contributing Section: VN
885 - D715
Optical Coherence Tomography versus Fluorescein Angiography for
Diagnosing and Treating Neovascular Age-Related Macular Degeneration: A
Sistematic Review
886 - D716
Investigation of Retinal Degeneration in Mice Using Fourier Domain Optical
Coherence Tomography
A. Tarantini1, M. Pala1, F. Menchini1, G. Virgili2, P. Lanzetta1, F. Bandello1, G. Polini1.
1
Ophthalmology, University of Udine, Udine, Italy; 2Ophthalmology, University of
Florence, Florence, Italy.
M.V. Sarunic1, J. Xu1, M.H. Khorasani1, J.N.B. Koo1, L.L. Molday2, R.S. Molday2.
1
Engineering Science, Simon Fraser University, Burnaby, BC, Canada; 2Department
of Biochemistry & Molecular Biology, Centre for Macular Research, University Of
British Columbia, Vancouver, BC, Canada.
Purpose: To systematically review the sensitivity and specificity of optical coherence
tomography (OCT) for diagnosing and managing neovascular age-related macular
degeneration (AMD) as compared to well-established gold standard test such as
fluorescein angiography.
Methods: We searched Medline, from 1966 to 2007. Two reviewers independently
assessed trial searches, studied quality with the QUADAS checklist and extracted
data. The target disease was neovascular AMD. A bivariate model was used to obtain
summary estimates of sensitivity and specificity and fit a summary receiver operating
characteristic (ROC) curve.
Results: Seven studies were considered eligible. These studies were of good quality
for most items of the QUADAS checklist, but most studies did not report masking of
examiners and did not describe how withdrawals and undetermined results were
treated. Sensitivity and specificity data could be extracted from 5 out of 7 studies
because appropriate cross-tabulations of index and reference tests were not reported
by the others. One of these studies assessed the performance of OCT to confirm or
exclude the diagnosis in patient with suspect CNV; the prevalence of CNV in these
patients was 64%, the sensitivity was 96% and the specificity was 66%, if OCT was
coupled with stereoscopic fundus photography the performance improved. Four
studies assessed the ability of OCT to diagnose the need for retreatment in patients that
were previously treated with PDT, in these the sensitivities varied between 65 % and
100%, the specificities varied between 43% and 80%. The result were too heterogeneous
to conduct a metanalysis and draw conclusions for clinical practice.
Conclusions: Optical coherence tomography is a valid tool for diagnosing neovascular
AMD compared to fluorescein angiography; this conclusion was supported by only
one study with high pre-test probability so the result cannot be apply in a screening
setting. The various OCT criteria, combined or alone, do not correlate well with leakage
on FA when assessing the need for PDT retreatment during follow up, particularly
the specificity is low.
CR: A. Tarantini, None; M. Pala, None; F. Menchini, None; G. Virgili, None; P.
Lanzetta, None; F. Bandello, None; G. Polini, None.
Support: None
Purpose: The purpose of this preliminary study is to investigate Fourier Domain
Optical Coherence Tomography (FD OCT) as a non-invasive tool for retinal imaging
in mouse models for retinal degenerative diseases.
Methods: A prototype spectrometer based FD OCT system was used in combination
with a custom optical beam-scanning platform. Images of the retinas from wild type,
rds, and rs1h knockout mice were acquired non-invasively using FD OCT with the
specimen anesthetized. Following euthanasia, invasive retinal cross sectional images
(histology) were acquired from a nearby region for comparison.
Results: The retinal layers could be identified in the FD OCT images, permitting
delineation and thickness measurement. Disorganization of the retinal layers and
retinal holes were observed in the rs1h knockout mouse (the model for X-linked
retinoschisis) as indicated in Figure 1.
Conclusions: FD OCT has been demonstrated for non-invasive imaging of retinal
degeneration in rds mice, and observation of retinal holes in rs1h knockout mice.
Acknowledgements: We acknowledge support from the President’s Research Grant
from SFU to MVS and NEI grant (EY 02422) to RSM.
Figure Caption: Fig. 1 FD OCT retinal images acquired from a (a) wild type and (b)
rs1h knockout mouse in vivo. Each FD OCT image consists of 800 lines. (c) Histology of
the rs1h knockout mouse retina, with DAPI nuclear staining overlaid on DIC image.
887 - D717
Application of Independent Component Analysis to Classify Non-Exudative
Amd Phenotypes Quantitatively From Vision-Based Derived Features in
Retinal Images
888 - D718
Aging and the Scattered Light Ratio in Confocal Polarized Light Imaging
B. Davis , S.R. Russell , M.D. Abramoff , T. Scheetz , S. Murillo , P. Soliz . VisionQuest
Biomedical, Albuquerque, NM; AOphthalmology, 2University of Iowa, Iowa City,
IA; 3Ophthalmology, University od Iowa, Iowa City, IA.
1
2A
3
2
1
1 1
Purpose: To apply computer-based feature detection to digital images for phenotyping
of patients with non-exudative (NE) age-related macular degeneration (AMD).
Methods: The dataset consisted of 100 digital images from 100 sequential patients with
NE AMD. Images were scanned from 35mm slides at 2400x2400 pixels and centered
on the fovea. The digital images were visually sorted into 12 fundus phenotypes,
based upon macular pattern. A independent component analysis (ICA) algorithm was
trained using the ‘leave-one-out’ method, from the two categories, temporal drusen
phenotype (TDP, >85% drusen temporal to the fovea), and small, distributed drusen
phenotype (SDDP, drusen < 63 microns, no radial inhomogeneity). To test whether
ICA could mimic human visual phenotyping, five images from the SDDP and six
images from the TDP were evaluated in masked fashion. Independent components
(ICs or features) were collected from two regions of the image (512x512 pixels centered
on fovea, 512x512 pixels 200 pixels temporal to fovea) for each of the images in the
two phenotype classes.
Results: Two feature scales (6x6 and 12x12 pixels) were found to maximize separation
of the two phenotypes based on 32 ICs for each scale. A regression analysis using
partial least squares of the 64 features showed perfect classification, in other words
100% accuracy in replicating the human-based classification of phenotypes. Using
only either set of features alone produced an 85% accuracy.
Conclusions: These results suggest that visually recognized fundus patterns (fundus
phenotypes) of NE AMD can be detected and defined using computer vision-based
methods. ICA demonstrates high accuracy in sorting fundus patterns in digital fundus
images and can objectively categorize fundus phenotypes when the phenotypes have
been defined based on subjectively chosen representative exemplars. Additional study
will be required to determine whether these or other subjectively or objectively defined
fundus phenotypes are associated with visual prognosis or genetically meaningful
relationships in AMD.
CR: B. Davis, VisionQuest Biomedical, I; VisionQuest Biomedical, E; S.R. Russell,
None; M.D. Abramoff, None; T. Scheetz, None; S. Murillo, VisionQuest Biomedical,
E; P. Soliz, VisionQuest Biomedical, I; VisionQuest Biomedical, E.
Support: University of Iowa, Dept. of Ophthalmology unrestricted funds., VisionQuest
Biomedical corporate support
CR: M.V. Sarunic, None; J. Xu, None; M.H. Khorasani, None; J.N.B. Koo, None; L.L.
Molday, None; R.S. Molday, None.
Support: We acknowledge support from the President’s Research Grant from SFU to
MVS and NEI grant (EY 02422) to RSM.
A.E. Elsner, D.A. VanNasdale, B.P. Haggerty, J.A. Papay, M.J. Cannon, C.J. Kenrick, S.A.
Burns. Optometry, Indiana University, Bloomington, IN.
Purpose: To probe structural changes to the retina with age that are too early or
subtle to be visualized as distinct features using a novel metric of scattered light.
To determine if this metric, the scattered light ratio, is related to aging in carefully
selected, normal subjects.
Methods: We used scanning laser polarimetry to separate reflected light from scattered
light. We acquired 3 sets of 15 deg, macular-centered images using a GDx with 780 nm
illumination (Zeiss). A pinhole before each detector minimized scattered light anterior
or posterior to the retina. Each set is 20 raw images, differing in input polarization,
from the crossed detector and 20 from the parallel detector. The scattered light ratio
is the proportion of light that was depolarized by multiple scattering. Thus, the
grayscale of the light not modulated by polarization (the minimum) was computed
from crossed detector data for each pixel. Assuming that scattered light reaches
both detectors equally, this ratio is (2 X the minimum of the modulation)/(average
light return). This ratio removes the effects of reflectivity of retinal and subretinal
structures, instrument laser power or gain, or alignment variation. Samples at 1 deg
from the fovea from 30 normal subjects, aged 15 - 30 yr, were compared to a group
50 - 75 yr. To quantify repeatability, the best data set was “Measurement 1,” and the
second best was “Measurement 2.”
Results: The scattered light ratio at 1 deg was 0.16 for the younger group and 0.25
for the older group, using Measurement 1. The older group had significantly more
scattered light, as expected (P < 0.0001). Measurements 2 ratios were also 0.16 and
0.25, without a significant increase in variability for either group.
Conclusions: At 1 deg from the fovea, there is significantly more scattered light on
average in healthy older retinas than in the younger retinas. This increase in light
scattering has a potential impact on vision. Despite low absorption of near infrared
light, the majority (75% or more) of light in healthy eyes was not multiply scattered,
given carefully focused, polarized light and a small confocal aperture. Thus, a change
in the distribution of scattered light may provide a sensitive method for detection
of pathology.
CR: A.E. Elsner, None; D.A. VanNasdale, None; B.P. Haggerty, None; J.A. Papay,
None; M.J. Cannon, None; C.J. Kenrick, None; S.A. Burns, None.
Support: NIH Grants EY007624 and EY017886
Copyright 2008 by the Association for Research in Vision and Ophthalmology, Inc., all rights reserved.
For permission to reproduce any abstract, contact the ARVO Office at pubs@arvo.org. Commercial Relationships are noted at the end of each abstract by “None” or with codes.
885-888
889 - D719
Automated Detection of Nonproliferative Diabetic Retinopathy
890 - D720
Foveal Localization and Polarimetric Image Comparisons Between Age-Related
Macular Degeneration and Normals
K. Ahrlich1, L. Subramanian2, K. Kavukcuoglu2, A. Rubinsteyn2, J. Young1.
1
Ophthalmology, NYU School of Medicine, New York, NY; 2Courant Institute of
Mathematical Sciences, New York University, New York, NY.
Purpose: To evaluate the sensitivity of retinal analysis software to identify
nonproliferative diabetic retinopathy and to differentiate diseased from normal
retinas.
Methods: A retrospective study was performed on digital fundus photos of 14 eyes
obtained from a database of known diabetics treated through Aravind Eye Hospitals.
An automated retinal analysis program was developed at New York University’s
Courant Institute of Mathematical Sciences to recognize lesions of nonproliferative
diabetic retinopathy, including dot-blot hemorrhages, microaneurysms, and hard
exudates. This adaptive learning program was given a training data set of 12 images,
after which it was tested on 3 randomly selected images. Sensitivities were determined
for the program in comparison with an ophthalmologist.
Results: The program correctly identified 234,439 (80%) background structure pixels,
2,555 (83%) hemorrhage pixels, and 4,322 (93%) exudate pixels. However, it occasionally
mislabeled structures such as optic disc and retinal vasculature as diabetic lesions.
Conclusions: Automated retinal analysis can be a useful adjunct to clinical evaluation
in diabetic retinopathy screening. Especially in medically underserved or remote
areas, automated analysis may increase the volume of patients to be screened for
diabetic retinopathy. With further post-processing, normal eyes should no longer be
misidentified by the computer program. This will allow eye care professionals more
time to devote to patients in underserved areas.
CR: K. Ahrlich, None; L. Subramanian, None; K. Kavukcuoglu, None; A. Rubinsteyn,
None; J. Young, None.
Support: None
891 - D721
Imaging the Retinopathy of Parkinson’s Disease
D.A. VanNasdale1, A.E. Elsner1, A. Weber2, M. Miura 3, B.P. Haggerty1, Y. Zhao1, J.A.
Papay1, M.J. Cannon1, C.J. Kenrick1, B.D. Hansel1. 1Optomemtry, Indiana Univ Sch
of Optometry, Bloomington, IN; 2Ophthalmology, University Hospital, Aachen,
Germany; 3Ophthalmology, Tokyo Medical University, Tokyo, Japan.
Purpose: To localize the fovea in subjects with non-exudative age-related macular
degeneration (AMD) and age-matched controls using scanning laser polarimetry. To
quantify tissue disruption using the variability of scattered light in AMD and control
subjects.
Methods: We used a scanning laser polarimeter (GDx, CZM) to image the macula in 19
eyes with non-exudative AMD and 19 age-matched controls. Each image series has 40
raw images: 20 input polarizations and 2 detectors, one parallel to the input polarization
and one perpendicular (crossed). We computed 18 images with differing polarization
content. A maximum phase image, indicating both the magnitude and orientation of
corneal/Henle fiber birefringence, was used to determine the foveal location. These images
also showed potential birefringence changes between drusen and adjacent retina . The
depolarized light image estimates scattered light at each pixel, since multiply scattered
light does not modulate with input polarization. We calculated the minimum of the
crossed detector output as a function of input polarization. Then, the scattered light
ratio was computed as 2 X the depolarized light image/the average image. The scattered
light ratio was computed at 4 regions of interest (85 x 85 microns) 1 deg eccentric from
the fovea. The variation in light scatter was normalized by calculating the coefficient
of variation (SD/mean) for each region of interest, and compared between AMD cases
and controls using ANOVA.
Results: The foveal location was easily determined from the birefringence images for all
subjects, despite significant disruption to the central macula in many AMD cases. Drusen
displayed differing reflection and polarization properties, which could be arranged
into three main categories: primarily specularly reflecting, primarily scattering, and
center/surround differences in reflecting vs. scattering. Most drusen did not provide
orientation changes in their birefringence, compared with adjacent retina, unlike large
regions of atrophy. ANOVA analysis indicated the coefficient of variation measurements
taken at 1 degree eccentricity were significantly greater in patients with AMD than in
controls (p=0.010).
Conclusions: Scanning laser polarimetry can be used to localize the fovea, even in the
presence of moderate AMD pathology. Disruption of the highly organized retina in AMD
leads to larger variation in light scattering.
CR: D.A. VanNasdale, None; A.E. Elsner, None; A. Weber, None; M. Miura, None; B.P.
Haggerty, None; Y. Zhao, None; J.A. Papay, None; M.J. Cannon, None; C.J. Kenrick,
None; B.D. Hansel, None.
Support: NEI Grant EY017886, NEI Grant EY 007624, NIH Grant EB002346
892 - D722
Functional Optical Imaging of Retina Reveals Patterns of the Ganglion Cell
Axon Arcades
M.E. Hajee1A,1B, W. March1A, D. Lazzaro1A, Z. Belakovskaya2, S. Glazman1B, I. BodisWollner1B,1A. AOphthalmology, BNeurology, 1SUNY Downstate Medical Center,
Brooklyn, NY; 2Ophthalmology, Long Island College Hospital, Brooklyn, NY.
D. Izhaky1, D.A. Nelson1, A. Grinvald2. 1Optical Imaging Ltd., Rehovot, Israel;
2
Neurobiology, Weizmann Institute of Science, Rehovot, Israel.
Purpose: To quantify whether Parkinson’s Disease (PD), a neurodegenerative
disease, affects the inner retina as measured by Fourier-Domain Optical Coherence
Tomography (OCT).
Methods: This is a prospective, multicenter study in which 46 consecutive PD eyes
and 27 normal eyes were examined. Patients were in stage III or earlier phase of PD.
Eighteen eyes were from non-medicated PD patients . All patients underwent a 12
point ophthalmological exam and an Optovue RTvue Fourier-Domain OCT was
employed using the MM4 and MM7 scans to examine the retinal nerve fiver layer
thickness (NFL). The mean ages of normal subjects and PD patients were 66.7 ± 13.5
and 66.4 ± 7.8 years (p=0.057) respectively.
Results: The mean superior NFL of the macula in normal subjects vs. PD eyes was
99.6 vs. 86.8 (p<0.001). The mean inferior NFL of the macula in normal subjects vs.
PD eyes was 97.4 vs. 85.5 (p<0.001).
Conclusions: The NFL in PD patients is thinner than normal in a statistically
significant manner. This change must be separated from glaucomatous change when
using the OCT. The effect of PD on macular thinning is consistent with previous
functional studies using the ERG. Retinal involvement in PD apparently is not limited
to dopaminergic amacrine cells.
CR: M.E. Hajee, None; W. March, None; D. Lazzaro, None; Z. Belakovskaya, None; S.
Glazman, None; I. Bodis-Wollner, None.
Support: NPF and NINDS
Purpose: Near-infrared light, outside the absorption range of the photoreceptors,
was used to optically monitor retinal activity in response to a well-defined visual
stimulus.
Methods: The measurements were carried out with the Retinal Function Imager (RFI)
(Optical Imaging, Ltd.). The RFI measures activity-dependent functional signals in
retinal image series recorded at chosen wavelengths. We measured changes in retinal
reflectance during short and long trials with two visual stimulus test patterns and
blank as a control. The two stimuli are either single flash or train of flashes at 4-30Hz
while recording in infrared from eyes of anesthetized monkeys.
Results: Imaging the intact retina of anesthetized macaque monkey in vivo, we found
a new functional signal localized to the axonal arches of the retinal ganglion cells
emanating from the activated retinal area. Other intrinsic signals differing in temporal
and spatial characteristics as well as their polarity were also observed.
Conclusions: Assessing the status of the axon arcades non-invasively might provide
a new objective indicator for retinal diseases, particularly glaucoma.
CR: D. Izhaky, Optical Imaging Ltd., E; D.A. Nelson, Optical Imaging Ltd., E; A.
Grinvald, Optical Imaging Ltd., I.
Support: None
889-892
893 - D723
Hyperspectral Imaging: A Non-Invasive System for Visualizing Retinal Oxygen
Saturation in Humans
894 - D724
Repeatability of Intrinsic Optical Imaging of the Retina’s Response to Optical
and Electric Stimuli
J. Elison, H. Toma, B. Khoobehi, R. Grigorian, E. Puissegur. Ophthalmology, LSU
Department of Ophthalmology, New Orleans, LA.
T. Mihashi1,2A, Y. Hirohara1,2A, Y. Okawa2A, T. Miyoshi2B, T. Fujikado2A. 1Research
Institute, Topcon Corp., Itabashi, Japan; ADepartment of Applied Visual Science,
B
Department of Physiology, 2Osaka University Medical School, Suita, Japan.
Purpose: To use a hyperspectral imaging (HSI) system as a non-invasive method
to measure oxygen delivery to the optic nerve head (ONH) and retinal vessels in
human subjects.
Methods: Fundus images of the optic nerve head, retina, and their overlying vessels
were obtained from healthy human subjects using the HSI system. Reflectance light
spectroscopy under constant illumination of ONH and retinal areas was performed
with HSI. Reflectance oxyhemoglobin and deoxyhemoglobin spectral curves were
generated from light reflected from each region of interest at wavelengths ranging
from 409 nm to 917 nm. A predetermined algorithm was used to calculate the relative
oxygen saturation indices from the different structures.
Results: The relative saturation indices for the arteriole, venule, and ONH areas were
found to be as follows: 3.1, 2.4, and 4.7.
Conclusions: This study non-invasively measures oxygen saturation levels in the eyes
of human subjects. We believe that this novel non-invasive approach to measuring
the oxygen levels in the ocular structures of human subjects will contribute to our
understanding of how oxygen is provided and used by the eye.
Structure
Relative Concentration
Oxygen Saturation
Arteriole
3.1
98%
Venule
2.4
76.4%
ONH
4.7
149%
CR: J. Elison, None; H. Toma, None; B. Khoobehi, None; R. Grigorian, None; E.
Puissegur, None.
Support: NEI R03EY012887 (BK), P30EY02377 (LSU Eye Center Core grant), and an
unrestricted challenge grant from Research to Prevent Blindness, New York, New
York (LSU Eye Center).
895 - D725
Testing AOSLO Measurements of Retinal Blood Flow
Z. Zhong, B. Petrig, Y. Chui, X. Qi, S. Burns. School of Optometry, Indiana University
Bloomington, Bloomington, IN.
Purpose: To test a new method for measuring blood flow in the human retina. This
method uses an AOSLO to directly measure the time required for red blood cells
(RBCs) to move across a horizontal scanning line.
Methods: An 840 nm (center wavelength) SLD was used as the light source. The AO
control of our system was maintained using a BMC MEMS deformable mirror and
a Shack Hartmann sensor operating in closed loop at 8 Hz. The imaging beam was
steered by an 8 kHz horizontal scanner and a 15 Hz vertical scanner to sweep across
the imaging region. The vertical scan was programmed to briefly stop on top of a
blood vessel while the horizontal scan repeatedly moved the beam across that line in
the imaging area. During this halt, all the image lines were collected from the same
location. In this period the image consists of a direct measure of the change in time due
to horizontal movement of red blood cells across the imaging region. Thus, each RBC
or RBC cluster was sampled several times while passing the horizontal scanning line,
forming a diagonal straight line. The slope of the diagonal line is the horizontal velocity
of the red blood cell, given the constant time interval between line scans. Velocities
were adjusted for the angle between the horizontal scanning line and the vessel flow.
10ms samples were obtained, avoiding contamination from eye movements. Vessels
with size from 10um to 100um were sampled in healthy subjects.
Results: Measured velocity in both arteries and veins fluctuates with the subject’s
cardiac cycle, with velocity fluctuation in arteries being larger, as expected. The peak
velocity for an artery was typically 300% that of the minimum, whereas for veins there
was only a 2:1 ratio in velocity across the cardiac cycle. For the arteries, the velocity
waveform showed a dicrotic notch after the systolic peak, which is very typical in
arterial pressure waveforms and is described in the literature to possibly result from
the closure of the aortic valve. Capillary velocities measured range from 1mm/s to
2 mm/s and in larger arteries sampled velocities went as high as 40mm/s at their
pulse peaks. Parabolic velocity profiles were measured across larger blood vessels.
We computed the average flow rate across the cardiac cycle. The sum of the calculated
flow rate in daughter vessels was very close to that in the parent vessel.
Conclusions: Direct imaging of blood flow is possible using an AOSLO. This technique
is sensitive to known variations in blood flow in human observers. This technique
has the potential to fill the gap in measurements between techniques such a Doppler
velocimetry, which can measure large vessels, and leukocyte imaging which can
measure small parafoveal capillaries.
CR: Z. Zhong, None; B. Petrig, None; Y. Chui, None; X. Qi, None; S. Burns, None.
Support: NIH-NEI Grant EY14375 EY04395
Purpose: Intrinsic optical imaging (IOI) can be a useful clinical tool to screen the
activity of retinal neurons. The use of the IOI of the retina was established by Tsunoda
et al (IOVS, 2004) and Abramoff et al (IOVS, 2006). We investigated repeatability of
the IOI of the animal retina because the precision should be known in future clinical
applications.
Methods: Two eyes of two cats were studied under general anesthesia. We used two
different kinds of stimuli. A rectangular region of the retinal was optically stimulated
by visible flickering light (4 Hz). The retinal ganglion cell axons around the optic
chiasm were stimulated by a train of monophasic electrical pulses. The frequency of
the train was 50 Hz. The retina was observed by a fundus camera (TRC-50lx, Topcon)
with near infrared light. Imaging was performed with a digital CCD camera at a frame
rate of 40 frames per second. We recorded the retina for 2s before the stimulus, then
for 4s during the stimulus and finally for 20s after the stimulus (Okawa, IOVS, 2007).
We performed independent component (IC) analysis in which the program finds nonGaussian components to separate the spatio-temporal signal pattern from noise. We
obtained ten ICs for one analysis. Mean correlation coefficients (MCCs) of the time
factor of ICs in the four measurements and analyses were calculated to investigate the
similarity of the signal components between different two measurements.
Results: The MCC of any two arbitrarily selected components between two different
measurements for the light stimulation was 0.18 ± 0.17 (SD). The MCC of the two signal
components was 0.85±0.05. This means that the time course of the signal components
stood out among other components. We found the same degree of similarity in the
stimulation of the chiasm The MCC of any two components was 0.19 ± 0.16. The MCC
of the two signal components was 0.93±0.04.
Conclusions: We found good correlation between signals in the two measurements.
The time courses of signals to the particular stimuli were often very similar. This
suggests that the intrinsic optical imaging of the retina is a promising method for
the clinic. We also found that the significant signal components can be selected from
other components with the correlation coefficients of the time courses.
CR: T. Mihashi, Topcon Corp., E; Y. Hirohara, Topcon Corp., E; Y. Okawa, None; T.
Miyoshi, None; T. Fujikado, None.
Support: None
896 - D726
Quantitative Retinal Blood Flow Measurement and Calibration Using Spectral
Domain Optical Coherence Tomography
H.M. Wehbe, M. Ruggeri, S. Jiao, C. Puliafito. Ophthalmology/McKnight Vision Res
Ctr, University of Miami/BPEI, Miami, FL.
Purpose: To present the latest progress in quantitative retinal blood flow measurements,
system calibration, and automatic retinal blood vessel parameter extraction with
ultrahigh resolution (~3 μm) spectral domain OCT (SD-OCT).
Methods: We have developed algorithms for measuring the retinal blood flow with
SD-OCT, which requires the calculation of the absolute blood flow velocity and vessel
diameters. We designed a specific arc shaped scan pattern for imaging individual
retinal blood vessels including a scan for eye motion compensation. To calculate
the absolute flow velocity the orientation of the vessel need to be extracted from
the OCT images, which includes the extraction of the lateral and depth coordinates
of the vessels. The lateral coordinates were calculated by using the concept of OCT
fundus shadowgram, a technique for generating high contrast fundus image first
developed by our group, with a series of signal processing. After determining the
lateral coordinates and the vessel diameter the depth coordinate of the vessels in each
OCT image was calculated from the corresponding Doppler image generated for each
of the arc scans. To verify the accuracy of this method a phantom simulating a blood
vessel with adjustable 3D orientation and flow rate was built and tested.
Results: The method was tested on selected retinal vessels of normal human eyes
non-invasively. A study on a retinal artery yielded a Doppler angle of 87.8º, a blood
flow velocity of 30.4±9.5 mm/s (mean and standard deviation) and an average blood
flow of 17 μl/min. The results of measurements for a retinal vein revealed a Doppler
angle of 87º, a blood flow velocity of 16.4±3.9 mm/s and an average blood flow of 2.01
μl/min. These results compared well with previously published data. The tests with
the blood vessel phantom showed that the technique has an error of less than 10%
compared with the actual set flow.
Conclusion: Quantitative retinal blood flow information can be calculated by
combining the information of OCT fundus shadowgram and the Doppler image
obtained with spectral-domain OCT. This technique was calibrated successfully with a
custom made phantom with a programmable flow. Accurate blood flow measurements
may benefit the study of eye diseases like glaucoma and diabetic retinopathy.
CR: H.M. Wehbe, None; M. Ruggeri, None; S. Jiao, None; C. Puliafito, None.
Support: NEI P30 Core Grant Ey014801, U.S. Army Medical Research and Materiel
Command (USAMRMC) grant W81XWH-07-1-0188
893-896
897 - D727
Snapshot Retinal Oximetry: Results of A Novel Four Wavelength Oximetry
Formula in Retinal Hyperspectral Imaging
898 - D728
Preliminary Findings on in vivo Fundus Pattern Projection Using the Universal
Retina Camera
A.A. Fawzi1, A.H. Kashani2, W. Johnson 3, D. Wilson 3, W. Fink4, G. Bearman 3, G. Martin 5,
M. Humayun1. 1Ophthalmology, Doheny Retina Institute, University of Southern
California, Keck School of Medicine, Los Angeles, CA; 2Ophthalmology, Doheny
Eye Institute, University of Southern California, Keck School of Medicine, Los
Angeles, CA; 3Snapshot Spectra, Los Angeles, CA; 4JPL/NASA; Caltech, Pasadena,
CA; 5Reichert, Inc, Buffalo, NY.
D. Link1, B.U. Seifert2, W. Vilser2. 1Institute of Biomedical Engineering & Informatics,
Technical University of Ilmenau, Ilmenau, Germany; 2Imedos GmbH, Jena,
Germany.
Purpose:To introduce a novel 4 wavelength oximetry formula, and report the results
of using this formula to study retinal oximetry using CTIS hyperspectral imaging
technology.
Methods: The new oximetry formula is used to study oximetry in retinal vessels and
the macular area in normal volunteers and patients with retinal vascular disease.
Results: Using this new formula, normal healthy vessels and macular background are
evaluated in 10 volunteers, and 20 patients with retinal vascular disease. The versatility
of this 4 wavelength formula in combination with CTIS is explored in various retinal
diseases including diabetic retinopathy. Attached are two images from our studies.
The first example shows excellent spatial resolution and correlation of high oxygen
saturation on oxygen saturation maps to areas of intraretinal microaneurysms and
intraretinal microvascular abnormalities in fluorescein angiography. The second image
shows great ability to study the difference in oxygen saturation between arteries and
veins in normal subjects.
Conclusions: The use of hyperspectral imaging offers the potential advantage of
unlimited wavelength combinations in exploring retinal oximetry. The versatility of
this novel formula in combination with hyperspectral imaging adds extra flexibility
in exploring retinal oximetry in health and disease.
.
CR: A.A. Fawzi, Reichert, Inc, F; A.H. Kashani, None; W. Johnson, Snapshot Spectra,
E; D. Wilson, Snapshot Spectra, E; W. Fink, Reichert, Inc, F; G. Bearman, Snapshot
Spectra, E; G. Martin, Reichert, Inc, E; M. Humayun, None.
Support: NIH core grant EY03040, REICHERT, Inc.
Purpose: The Universal Retina Camera (URC) was used to demonstrate an adaptive
spatial and temporal pattern projection onto the human retina.
Methods: The apparatus used was the URC, which is a fundus-camera based setup as
optical framework with two integrated spatial light modulators (SLM). Appropriate
SLM positions and the control of each pixel by VGA interfaces realise a programmable
optical path with the objective to have a spatial and temporal two-plane modulation.
Thus, it is possible to control the light entrance into the eye (anatomic pupil plane =
first plane) and to project patterns onto the retina (second plane) at the same time.
The cross-sectional beam shape in the anatomic pupil plane was set to annular
shape to assure the separation of illumination and imaging path. Local and temporal
modulation of the fundus illumination for both static and dynamic tests was realised.
A therefore required SLM was a light-transmissive micro display adapted to a 45
degrees field of view. In order to get maximum vessel contrast in the fundus images
green incoherent light was used. In vivo examinations were performed on healthy
subjects with mydriatic eyes.
Results: The results of preinvestigations and tests using an artificial eye could be
verified in healthy subjects. The effects of a two-plane modulation were demonstrated
and confirmed in vivo. Within a field of 45 degrees the human fundus can be
illuminated with arbitrary patterns. In static mode different illumination patterns
like checkerboards, slits, and spots were projected onto the fundus and imaged
simultaneously. In stimulation mode dynamic test patterns can be applied with
frequencies of 30 Hz, 15 Hz, and 7.5 Hz. Typical values for the contrast between
illuminated and blocked areas as measured from captured images are in the range
from 6:1 (on the macula) to 15:1 (outside the macula).
Conclusions: Preliminary results are presented using the URC for projecting arbitrary
patterns onto the living fundus. The single images and live image sequences are
captured to demonstrate the modulation effects on the human fundus. The used
setup enables the application of stimulation paradigms as well as methods for fundus
measuring in the area of 45 degrees. A variety of possible applications incorporated
in one single device makes the URC a promising tool for complex functional analysis
of the human fundus. Further research and optimisation is needed to improve
performance and handling of the URC.
CR: D. Link, None; B.U. Seifert, None; W. Vilser, None.
Support: BMBF: FKZ 13N8521, FKZ 03IP605
899 - D729
Qualitative and Quantitative Comparison of Functional MRI in NormallySighted Subjects and Patients With Outer Retinal Diseases
D.A. Poggel1A,2, L.J. Toth2, D.-S. Kim2, J.F. Rizzo1B,3. ABoston VA/ Boston University,
B
Boston VA Medical Center, 1Boston Retinal Implant Project, Boston, MA;
2
Center for Biomedical Imaging, Boston University Medical School, Boston, MA;
3
Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, MA.
Purpose: Functional MRI studies on patients with age-related macular degeneration
(ARMD) showed contradicting results with respect to the qualitative Gestalt of visual
cortex activation maps: either silencing of lesion projection zones (LPZ) or activation
of the LPZ by stimulation of peripheral intact areas. Our goal was to test the effects of
blindness on brain activation by performing a qualitative and quantitative comparison
of fMRI signals between normally-sighted subjects and patients with ARMD and
retinitis pigmentosa (RP).
Methods: We performed retinotopic mapping following a block-design approach.
For the polar angle dimension, a rotating wedge stimulus (flickering black-andwhite checkerboard) was used; for eccentricity mapping an expanding ring stimulus
was used. Data from 7 ARMD patients, 8 RP patients, and 9 healthy subjects were
acquired with a 3T Philips Intera MR Scanner. Data were analyzed with Brain Voyager
software (General Linear Model), signal amplitudes and locations of peak activation
were determined for each stimulus segment. Qualitative comparison was based on
linear correlation maps.
Results: Normally-sighted subjects showed a robust activation of early visual cortical
areas. In ARMD patients, the LPZ was silenced. In contrast, the LPZ in RP patients
showed widespread activation in response to stimulation of intact central visual field
areas. Quantitative analysis of retinotopy showed lower overall signal intensity and
smaller activated areas in both groups of patients vs. healthy subjects, and eccentricitydependent differences among all three groups with respect to the distribution of
brain signal intensity.
Conclusions: Partial blindness changes the topography of visual cortex activation.
Silencing in ARMD and spreading activation in RP patients suggest different processes
of plasticity after central vs. peripheral vision loss.
CR: D.A. Poggel, None; L.J. Toth, None; D. Kim, None; J.F. Rizzo, None.
Support: NIH Grant C-2726 to JFR
897-899
157. Aberrations and Optical Properties of the Eye Organizing Section: VI Contributing Section: RC
977 - D833
Dynamics of the Iris AO Deformable Mirror in a Wavefront Aberrometer
System
978 - D834
Validation of Programmable Liquid-Crystal Lens by Use of Hartmann-Moire
Wavefront Sensor
M.V. Subbaram1, I.G. Cox1, N. Doble2. 1Global R&D, Bausch & Lomb, Rochester, NY;
2
IRIS AO, Berkeley, CA.
M. Zhang1,2, T.V. Heugten 3, X. Wei2, S. Ravikumar2, J. Nan2, N.L. Himebaugh2, P.S.
Kollbaum2, L.N. Thibos2, Z. Wang1. 1Institute of Modern Optics, Nankai University,
Tianjin, China; 2School of Optometry, Indiana University, Bloomington, IN;
3
PixelOptics, Roanoke, VA.
Purpose: To report the repeatability and dynamics of wavefront measurement and
correction using a modified Bausch & Lomb Zywave I instrument incorporating an
IRIS AO deformable mirror.
Methods: The instrument consists of a Zywave I aberrometer modified to incorporate
an IRIS AO 37-segment, 3-micron stroke deformable mirror. Study 1 evaluated
the repeatability of the instrument on model eyes (10 measurements) that were
manufactured with known magnitudes of defocus and spherical aberrations. Study
2 involved introduction of different magnitudes of higher order aberrations (up to ± 1
micron in 0.1 micron increments) in the system to evaluate the dynamics of aberration
correction using the deformable mirror.
Results: For the model eyes, the standard deviation of all Zernike terms was 0.04
microns or less. Induction of defocus and higher order aberrations such as coma,
trefoil and spherical aberration resulted in the measurement of a linear increase in the
corresponding Zernike term (r > 0.97, p < 0.001) for both model eyes, with essentially
no coupling between these and other higher order terms.
Conclusions: Incorporation of a deformable mirror in a wavefront sensor designed
for measuring the wavefront aberration of the human eye provides a platform capable
of investigating the impact of induced higher order aberrations without introducing
an optical correction through contact lenses or surgery.
CR: M.V. Subbaram, Bausch & Lomb, E; I.G. Cox, Bausch & Lomb, E; N. Doble,
Iris AO, E.
Support: None
Purpose: A novel programmable liquid-crystal lens (PixelOptics,Inc.) was developed
as an alternate technology for controlling aberrations and providing dynamic power
changes. The current experimental study examined samples of this prototype liquidcrystal lens designed to correct defocus and spherical aberration.
Methods: The liquid crystal lenses can be modulated with an applied voltage. A Shearplate and Hartmann-Moire (HM) wavefront sensor were used to monitor spherical
defocus and spherical aberration (SA) at 532nm. Phase modulations across the lens
equal to Ar2 and A(r4-r2) were created with amplitudes up to 525 degrees. Repeatability
was assessed by taking 5 repeated measurements within a 3-minute period. Shearplate and wavefront sensor results were compared to theoretical expectations for
defocus and spherical aberration (lens diameters were 8.00 mm and 8.26 mm for the
r4-r2 and r2 lenses, respectively).
Results: Both the Shear-plate and wavefront sensor indicate that the r2 defocus lens
accurately produced a range of defocus values from -0.11 to +0.11 diopters of spherical
power (observed vs. predicted regressions have slopes of 0.999 and 0.949, and the
correlation coefficients of 0.996 and 0.999, with mean residual errors of 0.0472D and
0.00562D, respectively). The r4-r2 lens generated between +3 and -2.4 microns of SA,
but was less accurately controlled. Observed vs. predicted slope was 0.766, and the
correlation coefficient was 0.996, with mean residual errors of <0.536μm. Most of the
error occurred for high amplitude negative SA. The repeatability was generally with
in 5% and 1.5% for the r2 and the r4-r2 lens.
Conclusion: These prototype programmable liquid crystal lenses have the capability
to correct small levels of defocus and significant levels of SA with a high degree of
accuracy. This technology, therefore, has the ability to correct higher and lower order
monochromatic aberrations dynamically.
CR: M. Zhang, None; T.V. Heugten, None; X. Wei, None; S. Ravikumar, None; J.
Nan, None; N.L. Himebaugh, None; P.S. Kollbaum, None; L.N. Thibos, None; Z.
Wang, None.
Support: None
979 - D835
Gerchberg-Saxton Phase Retrieval in Phase Diversity Wavefront Sensing
980 - D836
Modeling of Dynamic Ocular Aberrations
T.D. Raymond, S. Farrer, P. Pulaski, D.R. Neal. Optical Engineering, AMO WaveFront
Sciences, Albuquerque, NM.
C. Leahy, C. Leroux, J.C. Dainty. Applied Optics Group, Dept. of Experimental
Physics, NUI Galway, Galway, Ireland.
Purpose: Phase diversity wavefront sensors (PDWS) offer promise in ophthalmic
applications because of their ability to measure speckled and discontinuous wavefronts.
We numerically investigate the efficacy of the iterative Gerchberg-Saxton (GS) phase
retrieval method to ophthalmic instruments where large dynamic range in defocus
and the presence of speckle make phase retrieval with standard methods based on
the intensity transport equation difficult.
Methods: Simulated PDWS data covering a typical range of typical ophthalmic
defocus aberration with a standard PDWS configuration were generated using the
Rayleigh-Sommerfled propagation integral equation. We processed these data using
the well-known iterative GS method. The input pupil diameter, sample plane spacing,
and irradiance characteristics were varied to study the robustness of the method and
its rate of convergence.
Results: We found the convergence rate and robustness of the GS method to be
particularly sensitive to the Fresnel number of the PDWS. The number of iterations
required to achieve a specified level of defocus accuracy increased approximately
exponentially with input pupil diameter for fixed sample spacing and diminished
as the reciprocal of the sample spacing. In contrast, we found a quadratic rather than
exponential dependence on the pupil diameter when speckle was introduced into
the irradiance pattern. This serendipitous effect significantly reduced the number of
iterations required for beams containing large numbers of speckle cells, as is typical
in ophthalmic aberrometers.
Conclusions: We found the GS method to be applicable to problems in ophthalmic
wavefont sensing and to be particularly well-suited to measurements in the presence
of speckle. The method worked best when sampled beams had significantly disparate
irradiance distributions and/or small Fresnel numbers. This method therefore
complements phase retrieval methods based on the intensity transport equation.
Figure 1: The number of iterations required to achieve a level of defocus accuracy increased
with aperture and diminished for beams with speckle.
Purpose: It is often observed that ocular aberrations undergo dynamic variations
over short periods of time. We propose to quantify and model these aberrations
based on appropriate measurements. This work may be helpful in understanding
the physiological causes of ocular aberration dynamics.
Methods: A Shack-Hartmann wavefront sensor has been built and calibrated to
meet our needs. It consists of a very sensitive camera that records data at 37.2 Hz,
coupled with a lenslet array that samples the exit pupil of the eye every 250 microns.
A scanning mirror is used to average down to zero unwanted effects of speckle. We
measured young healthy subjects under steady-state experimental conditions. Trials
were typically 30 seconds long, including 5 instances of blinking.
Results: Wavefronts were reconstructed using a Zernike polynomial expansion. Timefrequency plots of the Zernike modes showed that the ocular aberration dynamics
exhibit non-stationary behaviour, which complicated the modeling procedure. An
Autoregressive Integrated Moving Average (ARIMA) modeling approach was employed
to model the Zernike mode time series. The correlations between different Zernike
modes were also considered. The completed models were used to generate realistic
simulated data that could be treated as sample realisations of the true process.
Conclusions: The ARIMA approach provided accurate models and proved to be an
effective tool for generating simulated aberration data. These tools will be applied to
a larger population of subjects, and will hopefully be of use in the design and testing
of retinal imaging systems.
CR: C. Leahy, None; C. Leroux, None; J.C. Dainty, None.
Support: Science Foundation Ireland Grant SFI/07/IN.1606 and The Irish Research
Council for Science, Engineering and Technology
CR: T.D. Raymond, AMO, E; AMO, P; S. Farrer, AMO, E; AMO, P; P. Pulaski, AMO,
E; AMO, P; D.R. Neal, AMO, I; AMO, E; AMO, P.
Support: None
977-980
981 - D837
Binocular Correlation Between Aberration Dynamics
982 - D838
Wavefront Aberration Measurement in Dog and Cat Eyes
S.S. Chin, K.M. Hampson, E.A.H. Mallen. Optometry, University of Bradford,
Bradford, United Kingdom.
S.G. Rosolen1,2, B. Lamory3, N. Chateau 3, S. Picaud1,4, J.A. Sahel1,5, J.-F. Le Gargasson1,5.
1
INSERM UMR 592, Paris, France; 2Clinique Vétérinaire Voltaire, Asnières, France;
3
Imagine Eyes, Orsay, France; 4UPMC-Paris 6, Paris, France; 5Institut de la Vision,
Paris, France.
Purpose: The dynamic correlation between ocular aberrations beyond defocus is
currently unknown. We measured the aberrations simultaneously in both eyes by
using a binocular Shack-Hartmann sensor.
Methods: The binocular Shack-Hartmann sensor consists of a single laser source and
one camera for system simplicity and low cost. The sampling frequency is 20.65 Hz.
Hot mirrors are used to permit open-view observation. The target is a Maltese cross
presented on an LCD monitor, subtending 11.32 min of arc at the retina. Measurements
were carried out on six observers, aged between 23 and 33 years. Their refractive errors
ranged between plano to -7.00 D of sphere and less than -1 D of astigmatism. Each
measurement run lasted 24 s and five repeated measurements were taken. Coherence
function analysis was used to investigate the correlation between each aberration of
the two eyes in the frequency domain. Since the break-up of tears in the two eyes is
likely to be asymmetrical, a lowering of the coherence values would be expected. To
study the effect of tear film break-up, the experiment was repeated with dry front
surface scleral contact lenses. Due to the preservation of tear film between the lens
and the cornea, the blink reflex could be avoided and tear film break-up eliminated.
Zernike coefficients up to and including 8th radial order were calculated (excluding
tip and tilt).
Results: Results were subject-dependent. The coherence values were different for each
resolvable frequency component of each aberration. In general, the coherence values
were fairly low for each aberration (typically < 0.1). Averaging the coherence values
across frequecies and subjects showed that the correlation is highest for defocus (Z4),
followed by Z29 and Z26. The removal of tear break-up by means of scleral contact
lenses resulted in insignificant changes in the coherence values.
Conclusions: Dynamic correlation of ocular aberrations was studied in detail with
a binocular Shack-Hartmann sensor. Coherence function analysis shows that the
inter-ocular correlation between aberrations is dependent upon the subject, aberration
modes and frequency components. Generally the coherence values are low suggesting
poor correlation between the aberration dynamics of the two eyes. Uneven tear film
break-up does not account for this low coherence.
CR: S.S. Chin, None; K.M. Hampson, None; E.A.H. Mallen, None.
Support: None
Purpose: To evaluate the feasibility of ocular wavefront measurements in dog and cat
using a Hartmann-Shack aberrometer designed for the human eyes.
Methods: Two dogs and one cat were sedated (Methedomidine, 0.1 mg/kg) and their
right eye (RE) pupils were artificially dilated (tropicamide). Wavefront aberrations
were measured using an irx3 aberrometer (Imagine Eye, Orsay, France). Prior to each
measurement, the eye was aligned with the instrument optical axis by centering both
the eye pupil and Purkinje images. The Hartmann-Shack spot images were produced
by an array of 1024 microlenses that defined a 7.2x7.2 mm square area in the pupil
plane. In preliminary tests, spot image histograms were optimized by adjusting the
sensor acquisition time. Wavefront aberrations were then repeatedly measured 10
times in each animal’s RE. Spherical defocus, astigmatism and Zernike coefficients
up to the 8th order were finally analyzed.
Results: The optimal acquisition time was 10 ms for all animals, instead of 33 ms
when measuring human eyes. Refractive errors could be analyzed in a 6 mm pupil
diameter in all cases. The dilated pupil often exceed the sensor area. The average
refractive errors in dog #1, dog #2 and the cat were +2.9D(-2.0D)111°;-0.8D(-0.8D)126°
and +3.3D(-2.1D)98°, respectively while their Root Mean Square (RMS) higher-order
aberrations amounted to 1.9, 1.1, and 2.1 µm RMS respectively. Standard deviation
in sphere and cylinder was 1.0D in the cat and less than 0.5D in both dogs. Standard
deviation in the higher-order RMS was 0.8 µm in the cat and less than 0.5 µm in
both dogs. The observation of individual data revealed that a significant part of this
bvariability was due to blink-related changes in aberrations.
Conclusions: Wavefront aberrations can be measured in dog and cat using a
conventional aberrometer with reduced image acquisition time. The tested animals
had large higher-order wavefront aberrations. Our results reveal that one dog and
one cat are myopic with astigmatism and one dog is hyperopic with astigmatism.
Measurement reproducibility was poorer than usually found in human eyes and
strongly affected by blinks. This variability could be reduced using a larger sensor
area, specific head contention device and artificial tears.
CR: S.G. Rosolen, None; B. Lamory, Employee of Imagine Eyes, F; N. Chateau,
Employee of Imagine Eyes, F; S. Picaud, None; J.A. Sahel, None; J. Le Gargasson,
None.
Support: Grant from Pole de Competitivite MEDICEN Paris-Region
983 - D839
Analysis of High-Order Aberrations in Low-Cost Photorefraction
984 - D840
Evaluation of Higher-Order Aberrations in Children According to the Age
Y.-L. Chen1, L. Shi1, B. Tan1, J.W.L. Lewis1, M. Wang2. 1Center for Laser Applications,
Univ of Tennessee Space Inst, Tullahoma, TN; 2Wang Vision Institute, Nashville,
TN.
J. Pechmeja, L. Dieudegard, E. Denis, M. Fernandes, B. Mortemousque, D. Laurence, D.
Estelle, F. Milva, M. Bruno. 31240, CHU Bordeaux, Saint-Jean, France.
Purpose: To demonstrate the detection and quantitative analysis of high-order ocular
aberrations using photorefraction.
Background: Photorefraction (PR) is a viable large-scale screening technique that has
been used primarily to measure refractive errors and ocular alignment in small children.
However, the PR reflex carries double-pass wavefront information including aberrations
from diffraction and scattering.
Methods: The near-infrared, multi-meridian-eccentricity, adaptive PR technique (APR) is
employed to image eyes with normal and abnormal degrees of high-order (HO) aberrations
including keratoconus (KC) and ectasia. Pupil areas in APR images are located and rotated
to the corresponding detection meridian. Excluding the first Purkinje reflection, the pupil
images are then rescaled to their maximum and minimum intensity and are decomposed
into Zernike components up to the 6th order. Percentage contribution from each order is
calculated, and the results are classified into normal and abnormal groups.
Result: The images of each group of patients show distinguishable characteristic patterns
in. Fig.1 shows the analysis result. The spherical refraction gives the major contribution to
the P1+1 coefficient. The sign of this coefficient indicates convergent and divergent refraction.
P1-1 coefficient is the indication of cylindrical refraction. Significant levels of higher order
contribution are observed in keratoconus patients (shown in table and figure). The major
problem of false negatives are attributed to small pupil size (KC #18) and a high level of
refraction (KC #17; -17 diopter). Gaze angle does not seem to influence the result.
Conclusion: Infrared PR provides a simple, low-cost, objective, and versatile method in
screening high-order ocular aberrations.
Purpose: To investigated the influence of age and refractive error on higher-order
aberrations in children
Methods: Observational cross-sectional study
patients: one hundred trenty two eyes of 70 children old from 5 to 15 years. Manisfest
spherical equivalent was included enters -12.33 and +9.65 diopters.
Aberrometry was performed with the same wavefront analyser.
Results: Mean root mean square values of total aberrations according to the age were
0.30+/- 0.13 µm from 3 to 5 years, 0.29 +/- 0.11µm from 6 to 9 years and 0.36 µm +/0.16µm from 10 to 15 years. Sames results were found for third and fourth aberrations.
Mean root mean square values of total aberrations according to the refractive error
were 0.31 +/- 0.13 µm for children with no refractive error, 0.34 +/- 0.15 µm for average
hyperopes, 0.27 +/-0.11 µm for average myopes, 0.28 +/-0.10 µm for strong hyperopes
and 0.42 +/- 0.23 for strong myopes.
Conclusions: Higher-order aberrations seems to increase with age. Higher-order
aberrations were influenced by refractive error because strong myopes had greater
levels compared other groups.We do not have to note difference betwenn medium
and high pupillary size but we obtained values lower of totally, fourth and five order
aberrations when the pupillary size was lower than 6.6 mm.
CR: J. Pechmeja, None; L. Dieudegard, None; E. Denis, None; M. Fernandes, None; B.
Mortemousque, None; D. Laurence, None; D. Estelle, None; F. Milva, None; M.
Bruno, None.
Support: None
CR: Y. Chen, None; L. Shi, None; B. Tan, None; J.W.L. Lewis, E-Vision Tech. Inc., P; M.
Wang, E-Vision Tech. Inc., P.
Support: None
981-984
985 - D841
Monochromatic Higher Order Aberrations in Myopia and Hyperopia Before
and After Cycloplegia
986 - D842
Wavefront Aberrations in the Posterior Corneal Surface
J.C. He, W. Kok, J. Gwiazda. New England College of Optometry, Boston, MA.
L.A. Macfadden, L.S. Gray, N.C. Strang, D. Seidel. Vision Sciences, Glasgow
Caledonian University, Glasgow, United Kingdom.
Purpose:To measure monochromatic higher order aberrations (MHOA) in myopic and
hyperopic subjects, and determine the effect of cycloplegia upon these aberrations.
Methods:10 hyperopic (HYP: mean age 23.0±4.3 years; average MSE +5.69±0.83D)
subjects and 10 myopic (MYO: mean age 23.4±2.76 years; average MSE -4.95±1.90D)
participated with informed consent in the study. All subjects had VA of 0.0logMAR or
better in both eyes and cylindrical correction of ≤1.00DC in each eye. 3 measurements
of MHOA were obtained from both eyes using the Zywave aberrometer (Bausch &
Lomb) and an average MHOA profile expressed as Zernike coefficients was calculated.
Measurements were obtained pre- and post-cycloplegia, induced using 2 drops of 1.0%
cyclopentolate hydrochloride separated by 5 minutes. Post cycloplegia measurements
were obtained 40 mins after instillation of the cycloplegic. In all subjects, corneal
asphericity was measured using the Orbscan (Bausch & Lomb) and axial length was
measured using the IOLMaster (Zeiss).
Results:Mean axial length in the HYP group (21.49±0.70mm) was significantly shorter
(p<0.001) than the MYO group (25.77±1.37mm). The axial lengths of all subjects showed
a significant (p<0.001) negative correlation with MSE (r=0.80). Mean corneal asphericity
(-0.60±0.06) in the HYP group was significantly (p<0.001) greater than the MYO
group (-0.31±0.08). Mean total 3rd order aberration post-cycloplegia (0.52±0.24) in the
HYP group was significantly (p<0.001) greater than the mean pre-cycloplegia value
(0.30±0.13). Mean spherical aberration post-cycloplegia (0.78±0.24) in the HYP group
was significantly (p<0.0001) greater than found pre-cycloplegia (0.31±0.07). Also, the
mean post-cycloplegia defocus term (9.63±2.53) in the HYP group was significantly
(p<0.001) greater than pre-cycloplegia (6.21±2.84). By contrast, the MYO group showed
no significant differences in any of these parameters pre- and post-cycloplegia. Precycloplegia there were no significant differences between the MYO and HYP groups
for any MHOA. Post-cycloplegia the mean spherical aberration in the HYP group was
significantly (p<0.001) greater than that in the MYO group.
Conclusions:Spherical aberration is significantly greater in hyperopic eyes compared
to myopic eyes when accommodation is paralysed. Compensation of corneal MHOA by
crystalline lens MHOA is significantly greater in hyperopic eyes when accommodation
is active. These results may have implications for our understanding of refractive
error development.
CR: L.A. Macfadden, None; L.S. Gray, None; N.C. Strang, None; D. Seidel, None.
Support: College of Optometrists research Grant to LSG
Purpose: To measure wavefront aberrations in the posterior corneal surface and to
test their contribution to the aberrations in the whole eye.
Method: A Scheimpflug photography-based system (the Pentacam) was used
to measure corneal aberrations in the right eye for 21 young adults (6 males, 15
females, mean age = 26.1±3.6 yrs). 12 Scheimpflug images along 12 meridians for
each measurement were exported from the system and processed to derive corneal
heights of the anterior and the posterior corneal surfaces at the 12 meridians. After
correcting image distortions caused by both projection and refraction, the anterior
and posterior corneal surfaces were reconstructed and 35 Zernike aberrations of the
two corneal surfaces were derived through MatLab ray-tracing and Gram-Schmidt
procedures.
Result: For the main Zernike terms, the mean posterior corneal aberrations were
0.034±0.125 (oblique astigmatism, Z2-2), 0.276±0.120 (main axis astigmatism, Z22),
0.016±0.042 (vertical coma, Z 3-1), -0.047±0.049 (lateral coma, Z31), and -0.064±0.022
(spherical aberration, Z40). All main posterior corneal aberrations differed from zero
significantly (p<0.025) except of the vertical coma which approached to significance
(p= 0.08). The mean Zernike aberrations in the anterior cornea were 0.074±0.421
(Z2-2), -0.630±0.592 (Z22), -0.066±0.186 (Z3-1), -0.051±0.163 (Z31), and 0.211±0.112 (Z 40).
The posterior aberrations were 45.5% (Z2-2) and 92.2% (Z31) of the anterior corneal
aberrations and with the same sign, but 43.9% (Z22), 25.1% (Z3-1) and 30.2% (Z40) with
the opposite sign.
Conclusion: The posterior cornea plays an important role in balancing aberrations
in the anterior cornea, such as main axis astigmatism, vertical coma and spherical
aberration, for improving the optical quality of the whole eye. However, it also adds
more aberrations into the eye, e.g. oblique astigmatism and lateral coma.
CR: J.C. He, None; W. Kok, None; J. Gwiazda, None.
Support: NIH Core Grant
987 - D843
Posterior Corneal Aberrations and Their Compensation Effects on Anterior
Corneal Aberrations in Keratoconic Eyes
988 - D844
Internal and Total Optical Aberrations in Eyes With Ectopia Lentis Associated
to Marfan Syndrome
M. Chen1A,1B, S. MacRae1A,1B, G. Yoon1A,1B. ACenter for Visual Science, BDepartment of
Ophthalmology, 1University of Rochester, Rochester, NY.
Y.G. Lteif 1,2, C. Platkiewicz2A, L. Semai2A, D. Gatinel1,2. 1Ophthalmology, Rothschild
Ophthalmology Foundation, Paris, France; AOphthalmology, 2Bichat Claude
Bernard Hospital, Paris, France.
Purpose: To characterize posterior corneal aberrations in keratoconic (KC) eyes and
investigate compensatory effects between anterior and posterior corneal surfaces.
Methods: A total of 113 eyes, classified into four groups (37 advanced, 31 moderate,
14 mild KC eyes and 31 normal eyes) were measured with Orbscan IIz (Bausch &
Lomb). Both anterior and posterior corneal topographies for a 6 mm diameter were
decomposed by Zernike polynomials to compute corneal higher order aberrations
(HOA).
Results: Significantly larger amounts of posterior corneal aberrations were observed
in KC eyes than in normal eye group. The averaged higher order RMS wavefront errors
of posterior cornea were 0.94, 0.51, 0.22 and 0.19 µm in advanced, moderate, mild KC
and normal eyes, respectively. Posterior corneal coma was the most dominant posterior
HOA in KC eyes and its magnitude was 7 times larger than that found in normal eyes.
In advanced KC eye, the posterior corneal coma was orientated toward superior-nasal
direction with an orientation angle of 61±17 degree for OD and 66±17 degree for OS.
Positive vertical coma of the posterior cornea was more dominant (averaged magnitude
ratio of posterior corneal vertical to horizontal coma was 2 in advanced KC eye) in
advanced KC partially compensating for negative vertical coma in the anterior cornea.
On average, 23%, 24%, 24% of the anterior corneal coma was compensated by posterior
corneal coma in advanced, moderate and mild KC eyes respectively. However, no
significant compensation effects were found in normal corneas.
Conclusions: The significant residual uncorrected posterior corneal coma in KC eyes
can explain the clinical phenomena that KC patients with RGP lens still had lower
visual acuity than the normal vision. Since RGP lenses correct only anterior lower and
higher order corneal aberrations, significant amounts of residual posterior corneal
higher order aberrations, in KC eyes would limit the visual benefit obtainable with
conventional RGP lenses, while whole eye wavefront designed customized contact
lenses allows compensation for posterior corneal higher order aberrations.
CR: M. Chen, None; S. MacRae, Bausch and Lomb, F; Bausch and Lomb, C; G. Yoon,
Bausch and Lomb, F; Bausch and Lomb, C.
Support: NIH/NEI grant R01EY014999, Research to Prevent Blindness, NYSTAR/
CEIS and Bausch & Lomb grant
Purpose: To determine the differences in total, corneal and internal aberrations
between eyes diagnosed with ectopia lentis associated with Marfan syndrome and
normal eyes.
Methods: The Nidek OPD-Scan topographer and wavefront aberrometer was used
to measure the ocular and corneal aberrations to the sixth Zernike order for a 5 mm
zone. One hundred and forty four eyes (144 patients) diagnosed as normal and 53 eyes
(29 patients with Marfan syndrome) diagnosed with ectopia lentis were compared
for differences in root mean square (RMS) values of the total, corneal and internal
aberrations.
Results: RMS coefficients were lower in eyes free of ocular pathology (normal eyes)
compared to eyes with ectopia lentis with respective values of 2.88 ± 2.34 microns
and 3.98 ± 3.74 microns (p=0.01). The differences between the 2 groups were mainly
significant for the internal aberrations, with the mean RMS of Tilt, High Order,
Total Coma, Total Trefoil, Total QuadraFoil, Total Spherical aberration, and Total
Astigmatism respectively of 0.24 ± 0.13 microns, 0.27 ± 0.13 microns, 0.09 ± 0.04 microns,
0.15 ± 0.11 microns, 0.07 ± 0.06 microns, 0.13 ± 0.06 microns and 0.05 ± 0.04 microns
for normal eyes, and of 0.89 ± 1.14 microns, 0.68 ± 0.63 microns, 0.39 ± 0.43 microns,
0.4 ± 0.4 microns, 0.16 ± 0.18 microns, 0.11 ± 0.14 microns and 0.13 ± 0.13 microns for
eyes with ectopia lentis (p< 0.00001). There was no statistical difference in corneal
aberrations between the 2 groups except for the spherical aberration which was
significantly lower in eyes with ectopia lentis with a mean RMS value of 0.09 ± 0.06
microns versus 0.11 ± 0.04 microns (p=0.004).
Conclusions: Increased optical aberrations in patients with Marfan syndrome
are mainly caused by the internal aberrations secondary to ectopia lentis. Flatter
keratometry in Marfan patients (40.9 D vs 43.1 D in normal eyes) may account for the
lower corneal spherical aberration in these eyes.
CR: Y.G. Lteif, None; C. Platkiewicz, None; L. Semai, None; D. Gatinel, None.
Support: None
985-988
989 - D845
Visual Quality Measurements in Subjects With Age-Related Macular
Degeneration
990 - D846
Can Wavefront Aberrations Contribute to Visual Dysfunction in Stargardt’s
Macular Dystrophy?
C. Ortiz1, J.R. Jiménez1, F. Pérez-Ocón1, I. Muñoz2. 1Optics, University of Granada,
Granada, Spain; 2University Clinic Hospital of Granada, Granada, Spain.
E. Legrottaglie, L. Mosca, R. Fasciani, B. Falsini, L. Mosca, M. Giannico, E. Mandara, E.
Balestrazzi. Ophthalmology, Catholic University of Sacro Cuore, Rome, Italy.
Purpose: To test two differents devices, an aberrometer and a device that evaluates
visual quality based on double-pass technique in subjects with age-related macular
degeneration and to compare these data with experimental results from psychophysical
tests in order to evaluate visual performance.
Methods: Data on visual quality were taken from a WASCA aberrometer based on
Hartmann-Shack sensor and from a double-pass instrument (OQAS, Optical Quality
Analysis System) based on recording images of a point source after reflection in the
retina and a double pass through ocular media. For visual performance we determined
CSF (Contrast Sensitivity Function). Data were taken from fifty-three eyes of 35 subjects
with age-related macular degeneration.
Results: All ARMD-eyes had affected contrast sensitivity most severely in the medium
and high spatial frecuency range (p<0.05). For five patients (with one healthy eye) the
average Strehl Ratio diminished for ARMD-eyes demonstrating a great influence
of ocular aberrations and scattering with significance at p<0.05 in all cases. Data
on aberrometry also shown that higher-order aberrations were higher in the nonhealthy eye (p<0.05).
Conclusions: ARMD-eyes showed a worse visual performance and this is correlated
with data provided by objective data (aberrometer and double-pass technique)
CR: C. Ortiz, None; J.R. Jiménez, None; F. Pérez-Ocón, None; I. Muñoz, None.
Support: This research was supported by Organización Nacional de Ciegos Españoles
(ONCE), by Ministerio de Educación y Ciencia (Spain) grant FIS2006-01369 and Junta
de Andalucía (Spain) grant P06-FQM-01359.
Purpose: Previous studies (1) have shown that higher order wavefront aberrations may
affect central visual function in Retinitis Pigmentosa (RP). The aim of the present study
was to investigate the presence of wavefront aberrations in patients with Stargardt
macular dystrophy (SMD)
Methods: Wavefront aberrations were measured by Hartmann-Shack aberrometry
in 14 eyes of 7 patients with SR (mean age: 30.1 yrs ±13.8 SD) and in 11 eyes of 6 agesimilar visually normal control subjects (mean age: 32.2 yrs ± 15.0 SD). All patients
were submitted to complete ophthalmological examination, including best spectacle
corrected visual acuity (BSCVA), slit-lamp biomicroscopy, fundus examination,
standard Ganzfeld and focal ERG (FERG). Wavefront aberrations for 3 mm and 6
mm pupil diameters were defined as the root mean square (RMS)of the wavefront
aberration functions. Exclusion criteria were previous ocular surgery, cataract,
glaucoma or other ocular pathologies affecting vision.
Results: Clinical and FERG examinations confirmed the diagnosis of SMD in the
study group (mean FERG phase: -0.05 rad ± 0.50 SD; mean FERG amplitude: 0.29 µV ±
0.47 SD). The mean RMS for higher order wavefront aberrations was not significantly
different for patients with SMD (Spherical: -0.14 ± 0.13 SD; coma: -0.06 ± 0.21 SD; total
HOA: 0.24 ± 0.10 SD) compared to the control subjects (Spherical: -0.21 ± 0.10 SD; coma:
0.06 ± 0.26 SD; total HOA: 0.24 ± 0.09 SD).
Conclusions: No significant differences in the measurement of wavefront aberrations
were detected in SMD patients compared to control subjects. These findings suggest
that, unlike that observed in RP (1), wavefront aberrations do not contribute to visual
dysfunction in SMD.
1. Higher-Order Wavefront Aberrations in Retinitis Pigmentosa. Rajagopalan AS,
Shahidi M, Alexander KR, Fishman GA, Zelkha R. Optom Vis Sci 2005; 82: 623-628.
CR: E. Legrottaglie, None; L. Mosca, None; R. Fasciani, None; B. Falsini, None; L.
Mosca, None; M. Giannico, None; E. Mandara, None; E. Balestrazzi, None.
Support: fondi di ateneo, ex 60%
991 - D847
Changes in Higher-Order Aberrations and Contrast Sensitivity After
Instillation Of 0.5 % Timolol Gel-Forming Solution
992 - D848
Evaluation of Prescription Lenses That Correct Higher Order Optical
Aberrations
M. Daito1, S. Fukuda1, M. Asano1, Y. Hirohara2, T. Mihashi2, T. Hiraoka1, T. Oshika1.
1
Department of Ophthalmology, Institute of Clinical Medicine, University of
Tsukuba, Ibaraki, Japan; 2Technical Research Institute, Topcon Corporation, Tokyo,
Japan.
T. Kuyk1, L. McLin2, J. Kent2, L. Barnes2, J. Dykes1, P. Garcia1. 1Northrop Grumman,
Brooks City-Base, TX; 2Air Force Research Laboratory, Brooks City-Base, TX.
Purpose: It is well known that topical application of timolol gel-forming solution
causes blurred vision. Quality of vision and optical quality of the eye after instillation,
however, have not been examined in detail. We conducted the current study to
investigate sequential changes in ocular higher-order wavefront aberrations and
contrast sensitivity after instillation of 0.5 % timolol gel-forming solution.
Methods: In 20 eyes of 20 normal subjects (mean age, 22.8 ± 4.2 years old), ocular
wavefront aberration and contrast sensitivity were assessed before and 2, 5, and 30
minutes after instillation of 0.5 % timolol gel-forming solution. Ocular higher-order
aberration for a 4-mm pupil was measured with the Hartmann-Shack wavefront
analyzer every second for 10 seconds, and the root-mean-square (RMS) of the thirdorder, fourth-order, and total higher-order aberrations were determined. From the
time-course of changes in higher-order aberration for 10-second, the stability index
and fluctuation index were calculated. Stability index (SI) was defined as the slope of
the linear regression line of the higher-order aberrations. Fluctuation index (FI) was
defined as the average of the standard deviation of higher-order aberrations. Contrast
sensitivity was evaluated at four spatial frequencies; 3, 6, 12, and 18 cycles per degree,
and the area under the log contrast sensitivity function (AULCSF) was calculated.
Results: Total higher-order RMS significantly increased 2 and 5 minutes after
instillation (P < 0.05, paired t-test), but returned to the baseline level 30 minutes after
instillation. AULCSF was significantly reduced 2 and 5 minutes after instillation (P
< 0.01 and P < 0.05, respectively), but recovered to the baseline level thereafter. The
induced changes in AULCSF showed significant correlation with changes in total
higher-order RMS (Pearson, r = -0.421, P < 0.05). FI increased significantly 2 minutes
after instillation (P = 0.0001), and then returned to the pre-instillation level. SI showed
no significant changes throughout the study period.
Conclusions: Instillation of timolol gel-forming solution temporarily increases ocular
higher-order aberrations, leading to reduction in contrast sensitivity.
CR: M. Daito, None; S. Fukuda, None; M. Asano, None; Y. Hirohara, Topcon, I; T.
Mihashi, Topcon, I; T. Hiraoka, None; T. Oshika, None.
Support: None
Purpose: To determine if prescription lenses that incorporate a correction for higher
order optical aberrations in addition to lower order aberrations provide wearers visual
advantages over traditional prescription eyewear.
Methods: Using a within-subjects experimental design and a blind randomized
treatment order, visual performance of 20 subjects (mean age = 30.5) was compared
while wearing iZon® wavefront-corrected lenses (Ophthonix, Inc.) and traditional
prescription lenses (plano lenses if the subject was emmetropic). Visual acuity was
assessed with high (96%) and low (11%) contrast letter charts (Regan charts) at mean
luminance (white portion) of 100 and 3 cd.m-². In addition contrast sensitivity was
assessed at 5 spatial frequencies (0.9, 3, 6, 12, 18 cpd) using a staircase procedure at
grating mean luminance (5o gabor patches) of 30 and 3 cd.m-². Subjects were tested
twice, when the lenses were issued and at a minimum of 2 weeks later.
Results: Average acuity for the high contrast letters with the traditional lenses (plano
for emmetropes) was 20/11.5 and 20/14.8 at 100 and 3 cd.m-² compared with 20/11.4
and 20/15.1 with the Izon® lenses. None of the differences were significant. With
the low contrast letter charts, acuity was reduced (approximately 20/18 and 20/30
at 100 and 3 cd.m-²) but like the high contrast condition no differences between the
traditional and Izon® lenses were found. Similarly, in the contrast sensitivity data
no significant differences between the traditional and Izon® lenses were found at
any spatial frequency at either 30 or 3 cd.m-² (Figure 1).
Conclusions: When assessed with standard techniques, the Izon® lenses did
not provide wearers any visual advantage over traditional lenses. One caveat in
generalizing these results is that the sample tested consisted of a significant number
of young US Air Force personnel who had exceptionally good corrected or uncorrected
acuities even under low light test conditions and thus there may have been little room
for measurable improvement.
CR: T. Kuyk, None; L. McLin, None; J. Kent, None; L. Barnes, None; J. Dykes,
None; P. Garcia, None.
Support: Air Force Research Laboratory
989-992
993 - D849
Just Noticeably Levels of Aberration Corrections
R. Legras1,2, H. Rouger1,2. 1Laboratoire Aime Cotton, Orsay, France; 2Université Paris
Sud, Orsay, France.
Purpose: Customized contact lenses, intraocular lenses and refractive surgery are
now being developed to correct the main higher-order aberrations present in the eye
which are spherical aberration (SA), coma and trefoil to provide normal people with an
improved vision. We studied, using an Imagine Eyes CRX1 device, whether a partial
or a full correction of the three main aberrations is necessary to give a noticeable
improvement of the subjective vision quality.
Methods: Subjects viewed calculated images through a 5.5-mm artificial pupil and
an adaptive optics system to correct their eye aberrations. The images were obtained
by convolving an original 0.4-logMAR E-letter with a polychromatic point spread
function calculated with a numerical eye model including the desired wavefront
defined on a 6-mm pupil size. Three subjects made side-by-side comparisons between
the non-corrected aberrations image (NCAI) (e.g. typical higher-order aberration up
to 6th radial order of 0.35-µm RMS, including 0.128, 0.169 and 0.133-µm respectively
of SA, coma and trefoil) and one of the 27 partially corrected variant images (e.g. no,
half or total correction of each of the 3 main aberrations). Each of the 27 images was
compared 50 times to the NCAI. A percentage (e.g. subjective preference, SP) lower
than 25%, meant that the partially corrected variant images appeared noticeably
clearer than the NCAI.
Results: The subjective preference was found to be significantly correlated with
the remaining RMS level of aberrations (r=0.82) and the MTF integrated between
5 and 15-c/deg (MTFa, r=0.92). An analysis of variance was carried out to compare
the change in subjective preference with each aberration correction conditions. A
significant difference of SP was found with change of SA correction (F=5.32, p=0.014)
and with change of coma correction (F=5.92, p=0.009) but not with the correction of
trefoil (F=2.23, p=0.133). A noticeable improvement in the image quality was found
when the following two conditions were fulfilled: a half or full correction of SA and
coma. We measured that 0.13-D of defocus is just noticeable (e.g. a SP of 25%) when
testing in the same conditions.
Conclusion: The subjective quality of vision of a subject with typical aberrations
could be noticeably improved by an half or a full correction of both SA and coma,
this gain is comparable to 0.13-D of defocus blur correction. However, the effect of
the correction of the trefoil appears negligible.
CR: R. Legras, None; H. Rouger, None.
Support: None
994 - D850
The Applicability of Image Quality Metrics in the Estimation of the SpheroCylindrical Refraction From Wavefront Data of Normal Eyes
D. Iskander, M.J. Collins, T. Buehren, B. Davis. School of Optometry, Queensland
University of Technology, Kelvin Grove, Australia.
Purpose: To evaluate the potential advantage of a range of image quality metrics (IQMs)
over pupil plane metrics in the objective determination of the sphero-cylindrical
(SC) refraction.
Methods: Data from both eyes of 60 normal subjects were used. Subjective spherical
refractive correction ranged from −8.5D to +1.5D and cylindrical correction from
−3.75D to 0D. All subjects underwent subjective refraction in mesopic luminance
conditions, viewed the 20/20 line of a high contrast Bailey-Lovie acuity chart, and
provided subjective feedback to achieve optimal image quality. The same clinician
performed all subjective refractions. The objective refraction was assessed from the
wavefront aberrations measured with a COAS wavefront sensor. In the pupil plane,
estimates based on lower and higher order Zernike polynomials as well as the concept
of refractive Zernike power polynomials (Ophthal. Physiol. Opt., 27:245-255, 2007) were
used to derive the objective SC correction. In the image plane, a range of IQMs was
used including the entropy of the PSF, neural sharpness, visual Strehl ratios based
on MTF and OTF, and the augmented VSOTF. To determine the SC correction from
the IQMs, an optimization routine was developed that would mimic the method of
subjective refraction. First, the initial estimate of the SC correction was removed from
the wavefront data. This was followed by the addition of a range of SC corrections
to the residual wavefront and calculation of the IQMs. The resultant SC estimate
that corresponded to the best IQM outcome was used to adjust the initial estimate
of the SC refraction.
Results: The SC refraction was represented in vector components M, J0, and J45. For
the pupil plane based metrics, the best result has been achieved with the refractive
Zernike power polynomials resulting in r2 values of 0.97, 0.85, and 0.81 for M, J0, and
J45, respectively. Correspondingly, PSF entropy achieved r2 values of 0.97, 0.82, and
0.61; neural sharpness 0.97, 0.82, and 0.59; VSMTF 0.97, 0.78, and 0.53; VSOTF 0.97, 0.73,
and 0.51; and augmented VSOTF 0.97, 0.78, and 0.58.
Conclusions: Despite having taken account of pupil appodization and neural weighting
vision quality metrics derived in the image plane do not provide any substantial
advantages over simple pupil plane metrics in the determination of the objective SC
refraction for normal eyes. The recently introduced concept of refractive Zernike power
polynomials that represent the wavefront information in the refractive power domain
provides the best correlation with the subjectively evaluated refraction.
CR: D. Iskander, None; M.J. Collins, None; T. Buehren, None; B. Davis, None.
Support: None
995 - D851
Pattern Recognition as a Retinal Image Quality Metric
996 - D852
Model-Observer Performance for Adaptive Optics Corrected Functional Vision
C.D. Pinto1A, A.C. Kingston1A, P. Ludington1A, M.S. Venkiteshwar1B. AOptical Design &
Metrology, BClinical Research Administration, 1Bausch & Lomb Inc, Rochester, NY.
E. Dalimier, C. Dainty. Experimental Physics, National Univ of Ireland, Galway,
Galway, Ireland.
Purpose: To evaluate and compare a new objective image quality metric, Pattern
Recognition, to the Visual Strehl (VSOTF), Neural Sharpness (NS), and Normalized
MTF (SIQ) metrics and results of a psychophysical study on the perception of subjective
blur.
Methods: 25 blurred images were created by convolving an asymmetric (F) and a
symmetric (+) character with the point spread function of a Liou-Brennan model eye
(with and without coma) across 5 levels of defocus and spherical aberration. 15 subjects
were required to rank these images from “least” to “most” blurred images.
A novel, commercially available metric, Pattern Recognition, was used to provide
a score from 0 to 1000 for each of the blurred characters which accounts for the
phase transfer function. A score of 1000 corresponds to a diffraction limited image.
Correlation analysis was performed between subjective blur ranks to Pattern
Recognition ranks. The results were compared to that obtained between VSOTF, NS,
and SIQ metrics to subjective blur ranks.
Results: For the images convolved with coma on the Liou-Brennan model eye, the
correlation coefficient (r) between the Pattern Recognition metric and the subjective
blur rank scores from the psychophysical study was 0.874 (p<0.0001) for the symmetric
‘+’ target and 0.839 (p< 0.001) for the asymmetric ‘F’ target. For the images convolved
without coma in the model eye, the correlation increased to 0.94 and 0.91 (p<0.0001)
for the ‘F’ and ‘+’ targets, respectively.
Correlation between commonly used metrics and subjective blur ranks will be
discussed and compared to that with Pattern Recognition.
Conclusions: For both symmetric and asymmetric characters, Pattern Recognition
is significantly correlated to subjective perception of blur. Incorporating the phase
of the optical transfer function by using Pattern Recognition could provide better
understanding of subjective blur perception.
CR: C.D. Pinto, Bausch & Lomb, E; A.C. Kingston, Bausch & Lomb, E; P. Ludington,
Bausch & Lomb, E; M.S. Venkiteshwar, Bausch & Lomb, E.
Support: None
Purpose:Adaptive Optics (AO) techniques have recently been used to highlight the
impact of higher-order (HO) ocular aberrations on vision. It has also been shown
experimentally that neural contrast sensitivity can moderate the optical blur at low
light level (IOVS 48, E-Abstract 1512, 2007). The purpose of this study was to derive
a multi-task ideal observer model which accounts for individual optical filtering
and light-dependent neural filtering, to understand better their joint effect on visual
performance.
Methods:The work was based on a classical multi-class ideal observer model.
Customised optical filtering was calculated from measured ocular wavefront errors
and light-dependent neural filtering was constructed from weighted visual channels.
A spatial frequency analysis was performed on the visual stimulus to qualitatively
discuss the joint effect of neural and optical contrast sensitivity on the observer
performance. The numerical performance of the model-observer was computed with
a multi-class separability measure and related to the experimental results recently
obtained for a multi-class functional sensitivity visual test. The results were compared
in terms of the AO visual performance ratio (ratio of the performance with AO
correction of HO aberrations to that without correction), for seven different subjects,
and a set of pupil sizes and light levels.
Results:The model numerical results showed good agreement with the experimental
results for the set of seven subjects, and for the different pupil sizes. The numerical
results, as well as the spatial frequency characteristics analysis, also supported the
trend of the AO visual performance ratio to decrease as the light level is decreased.
Conclusions:Although some more individual data (concerning the neural contrast
sensitivity) is required for a full quantitative validation, the model showed good
agreement with previously obtained experimental results. In particular, it supports
the analysis that at low retinal illuminance levels, neural factors limit the effect that
increased higher-order aberrations can have on functional visual performance.
CR: E. Dalimier, None; C. Dainty, None.
Support: SFI Grant SFI/01/PI.2/B039C
993-996
Monday, April 28, 8:30 AM - 10:15 AM Hall B/C Poster Session Program Number/Board # Range: 1422-1441 / D633-D652
226. Refractive Error Organizing Section: VI Contributing Section: LE
1422 - D633
Prevalence of Astigmatism in Native American Children 6 Months to 8 Years of
Age
1423 - D634
Prevalence of Strabismus and Heterphoria in a Population of Native American
Children
E.M. Harvey, C.E. Clifford-Donaldson, T.K. Green, J.M. Miller, V. Dobson.
Ophthalmology and Vision Science, University of Arizona, Tucson, AZ.
K.A. Garvey, J.M. Miller, V. Dobson, E.M. Harvey. Ophthal and Vision Sci, Univ of
Arizona, Tucson, AZ.
Purpose: To determine the prevalence of high refractive astigmatism in Native
American (Tohono O’odham) children age 6 months to 8 years.
Methods: Children were recruited through Women, Infants and Children (WIC)
clinics, the Head Start Program, and K and 1st grade elementary school classrooms on
the Tohono O’odham Reservation from September 2005 to November 2007. Three right
eye (RE) non-cycloplegic SureSight (ncSS, Welch Allyn) autorefraction measurements
were attempted on all children, and the median cylinder was used to estimate amount
of astigmatism present. In addition, for children age 3 years and older, gold standard
estimates of RE astigmatism (cRmax, cycloplegic autorefraction (Nikon Retinomax))
were also obtained to assess the accuracy of ncSS measurements.
Results: Measurements were attempted on 956 children; no ncSS estimate could be
obtained on 9 children due to poor cooperation. Analyses of data from children 3 and
older (n=486) indicated that ncSS tended to overestimate astigmatism, compared to
cRmax measurement (cRmax = -0.06 + 0.63 * ncSS, R 2=0.69), and that in 95% of ncSS “out
of range” measurements, cRmax indicated that astigmatism ≥ 2.00D was present. The
regression equation was applied to median ncSS measurements for all subjects, and
RE astigmatism was estimated based on this corrected ncSS estimate. More children
< 1 year old had ≥ 1.00D of astigmatism compared to older age groups (70% vs < 55%
in all older age groups, all ps< 0.05 before Bonferroni correction, all ps except < 1 year
vs. 2 to < 3 years and 5 to < 6 years < 0.05 after correction). More < 1 year olds than 1 to
<4 year olds, and more 5-6 year olds than 1 to <3 year olds had ≥ 2.00D of astigmatism
(ps < 0.05 before Bonferroni correction, not significant after correction).
Conclusions: Results are consistent with reports from other populations that suggest
that high astigmatism is more prevalent during the first year of life than in subsequent
years. However, as reported with data from older children from this population, the
overall prevalence of astigmatism is greater than the prevalence observed in other
non-Native American populations.
Purpose: To determine the prevalence of strabismus and heterophoria in children
between 3.0 and 9.1 years of age who are members of a Native American population
with a known high prevalence of astigmatism.
Methods: Subjects were 595 children enrolled in Head Start, kindergarten, or first
grade during September 2005 through September 2007 in schools on the Tohono
O’odham Reservation. Distance and near unilateral and alternate cover tests were
performed on each child by an ophthalmologist or optometrist.
Results: Strabismus was detected in 1.0% of subjects. Two subjects (0.34%) were found
to have esotropia and four subjects (0.67%) had exotropia. Heterophoria was detected
in 3.7% of subjects, with exophoria accounting for the majority (91%) of these.
Conclusions: The prevalence of strabismus in this study is lower than previously
published studies of children, where the prevalence has been reported to range from
1.3% in 6 to 12-year-old Japanese children (Matsuo et al, Ophthalmic Epidemiology,
2005) to 2.4% in Hispanic and 2.5% in African American children 6-72 months old
(MEPEDS, Ophthalmology, 2007) to 3% in Minnesota children ≤6 years of age (Govindan
et al, Ophthalmology, 2005 and Greenberg et al, Ophthalmology, 2007) to 5.3% in entrylevel school children in Wales (Graham, British Journal of Ophthalmology, 1974). Few
studies have focused specifically on the prevalence of heterophoria in this age group.
However, one study reported esophoria at near in 7% and exophoria at near in 32% of
kindergartners in a U.S. community (Walline et al, Optometry and Vision Science, 1998),
values that are higher than heterophoria prevalence values in our population.
CR: K.A. Garvey, None; J.M. Miller, None; V. Dobson, None; E.M. Harvey, None.
Support: NIH/NEI Grant EY13153, Research to Prevent Blindness
Prevalence by Age
1 to <2
Amount of
<1 Year
Years
Astigmatism (n=214)
(n=132)
≥ 1.00D
70%
48%
≥ 2.00D
36%
20%
2 to <3
Years
(n=115)
55%
20%
3 to <4
Years
(n=125)
48%
25%
4 to <5
Years
(n=152)
52%
29%
5 to <6
Years
(n=65)
55%
38%
6 to <7
Years
(n=88)
41%
26%
7 to <8
Years
(n=56)
41%
27%
CR: E.M. Harvey, None; C.E. Clifford-Donaldson, None; T.K. Green, None; J.M.
Miller, None; V. Dobson, None.
Support: NIH Grant EY13153 (EMH) and Research to Prevent Blindness
1424 - D635
The Relation Between Magnitude of Anisometropia (Spherical Equivalent and
Astigmatic) and Amblyopia in a Population of Children With a High Prevalence
of Astigmatism
V. Dobson, J.M. Miller, C.E. Clifford-Donaldson, E.M. Harvey. Department of Ophthal
and Vision Science, University of Arizona, Tucson, AZ.
Purpose: To determine the relation between magnitude of anisometropia (spherical
equivalent [SE] and astigmatic), and best-corrected interocular acuity difference (IAD),
and stereoacuity (SA), in children who are members of a Native American Tribe with
a high prevalence of astigmatism.
Methods: Subjects were 972 children 4-13 years of age who attended school on
the Tohono O’odham Reservation and who did not have non-refractive ocular
abnormalities, based on an eye examination, with cycloplegic refraction. Monocular
best-corrected visual acuity was measured with ETDRS letter charts at 4 m and
best-corrected SA was measured with the Randot Preschool Stereoacuity test at 40
cm. Results were examined for 4 groups: Control (CON) group: <0.25 diopter (D)
SE anisometropia and < 0.25 D cylinder (cyl) anisometropia, Spherical Hyperopic
Anisometropia (SHA): hyperopic SE in both eyes, ≥ 0.25 D SE anisometropia, and <1.00
D cyl anisometropia; Spherical Myopic Anisometropia (SMA): myopic SE in both eyes,
≥ 0.25 D SE anisometropia, and <1.00 D cyl anisometropia; and Cyl Anisometropia
(CA): ≥ 0.25 D cyl anisometropia and <1.00 D SE anisometropia.
Results: Visual acuity data were obtained from 969 children and stereoacuity data
were obtained from 964 children. Mean CON (n=115) IAD was <1 logMAR line on the
ETDRS chart. In the SHA group, mean IAD was not significantly different from CON
IAD in children with 0.25 to <1.00 D (n=290) of SHA, but was significantly greater (>2
logMAR lines) in children with ≥ 1.0 D of SHA (n=15, p<0.001). In the SMA group,
mean IAD was not significantly different from CON IAD for children with 0.25 to
<1.00 D (n=83), or for children with ≥ 1.0 D (n=11) of SMA. In the CA group, mean
IAD was not significantly different from CON IAD in children with 0.25 to <3.00 D
(n=627) of CA, but was significantly greater (>2 logMAR lines) in children with ≥ 3.0
D of CA (n=8, p<0.001). For SHA, SMA, and CA groups, ≥ 0.50 D of anisometropia
produced a significant reduction in average best-corrected SA.
Conclusions: The amount of anisometropia that results in amblyopia (a significant
difference between eyes in best-corrected visual acuity) is less in children with a
difference in hyperopic spherical refractive error between eyes than in children with
a difference in cylindrical refractive error between eyes. However, even a small (≥ 0.50
D) amount of spherical hyperopic, spherical myopic, or cylindrical anisometropia is
sufficient to disrupt best-corrected stereoacuity.
CR: V. Dobson, None; J.M. Miller, None; C.E. Clifford-Donaldson, None; E.M.
Harvey, None.
Support: NIH Grant EY013153 (EMH); Research to Prevent Blindness
1425 - D636
Predictors of Amblyopia Subtypes in a Population of Children With a High
Prevalence of Astigmatism
J.M. Miller, V. Dobson, C.E. Clifford-Donaldson, E.M. Harvey. Ophthal & Vision
Science, University of Arizona, Tucson, AZ.
Purpose: To determine the utility of anisometropia and stereoacuity (SA) in predicting
subtypes of amblyopia in children who are members of a Native American Tribe with
a high prevalence of astigmatism.
Methods: Subjects were 952 children 4-13 years of age who attended school on the
Tohono O’odham Reservation and who did not have non-refractive ocular abnormalities,
based on an eye examination, with cycloplegic refraction. Monocular best-corrected
visual acuity was measured in each eye with ETDRS letter charts at 4 m and bestcorrected stereoacuity (SA) was measured with the Randot Preschool Stereoacuity
test at 40 cm. Parents reported history of spectacle wear (HxRx). Anisometropia was
classed as either being spherical equivalent (SEAniso) or cylindrical (CylAniso) by
vector methods.
Results: Children were classified as Non-Amblyopic (NA), with better seeing eye
(BSE) acuity of 20/32 or better, and less than 2 logMAR Line Difference (2LD) between
eyes (n=556); Unilateral Amblyopia with BSE 20/32 or better, ≥ 2LD; Symmetric
Bilateral Amblyopia with both eyes worse than 20/32 and <2LD; Asymmetric Bilateral
Amblyopia with both eyes worse than 20/32 and ≥2LD. Multinomial logistic regression
was used to predict subtypes of amblyopia by SA, SEAniso, and CylAniso after
adjusting for HxRx and age. Z score probabilities are shown in the Table, with No
Amblyopia (n=556) as comparison group:
Amblyopia Type
Unilateral
Symmetric Bilateral
Asymmetric Bilateral
n
101
245
50
SA Z, p|Z|
2.16, 0.031
7.70, 0.000
3.28, 0.001
SEAniso Z, p|Z|
3.71, 0.000
-0.46, 0.643
1.00, 0.315
CylAniso Z, p|Z|
1.05, 0.295
5.85, 0.000
4.16, 0.000
Conclusions: For all subtypes of amblyopia, stereoacuity has significant predictive
value. However, for amblyopia in which one eye sees at least 20/32, Spherical
Equivalent Anisometropia is most predictive, while for cases of bilaterally reduced
vision in this population, Cylinder Anisometropia is most predictive of the presence
of amblyopia.
CR: J.M. Miller, None; V. Dobson, None; C.E. Clifford-Donaldson, None; E.M.
Harvey, None.
Support: NIH Grant EY013153 (EMH); Research to Prevent Blindness
1422-1425
1426 - D637
Astigmatism and Higher-Order Aberrations Measured With a Handheld
Aberrometer in Native American Children
1427 - D638
Ametropia, Preschoolers’ Cognitive Abilities and Effects of Spectacle
Correction at 6-Month Follow-Up
E.A. DeHoog1A, C.E. Clifford-Donaldson1B, E.M. Harvey1B, J.M. Miller1B, V. Dobson1B, J.
Schwiegerling1A. AOptical Sciences, BOphthalmology, 1University of Arizona, Tucson,
AZ.
A.-C. Roch-Levecq1A, B.L. Brody1B, R.G. Thomas1C, S.I. Brown1A. AOphthalmology,
B
Ophthalmology and Family and Preventive Medicine, CFamily and Preventive
Medicine, and Neurosciences,, 1Univ of California-San Diego, La Jolla, CA.
Purpose: To compare astigmatism measurement with a custom handheld aberrometer
and the Retinomax autorefractor, as well as evaluate higher order aberrations in
preschoolers with a high prevalence of astigmatism.
Methods: Cycloplegic cylinder error was measured in a sample of 15 Native American
preschoolers, aged 3.3 to 5.1 years, using a portable Shack Hartmann aberrometer,
(PeWE). The results obtained by the PeWE were compared with cycloplegic Retinomax
autorefractometer (Nikon, Melville, NY) measurements. For each child, repeated
measures from the PeWE were used to calculate J0 and J45 crossed cylinder terms
and averaged to give a single mean J0 and mean J45 for each child. These mean values
were compared to the cylinder refraction obtained with the Retinomax converted to
J0 and J45. Bland Altmann plots were calculated to determine the bias and variability
between the two devices. Wavefronts obtained with the PeWE were reconstructed
and the magnitude of spherical aberration and coma was determined.
Results: Bland Altmann plots showed 0.5 D and 0.25 D bias between the Retinomax
Autorefractometer and the PeWE for J0 and J45, respectively. The PeWe gives a lower
magnitude of cylinder than the Retinomax. There also appeared to be a systematic
increase in the difference between the two devices as cylinder error increased, with
the PeWE giving progressively lower levels of cylinder at higher errors. The average
level of spherical aberration for a 5.7 mm pupil was 0.00 ± 0.25 microns. The average
magnitude of coma was 0.49 ± 0.32 microns.
Conclusions: We were able to obtain both PeWE and Retinamox measurements for all
15 children. There is a strong correlation between the J0 values for the PeWE and the
Retinomax, with r2 = 0.84 (p<0.001). The correlation between the J45 terms, however,
was much lower (r2 = 0.35, not significant). The low correlation for J45 is likely due to
the low prevalence of obliquely oriented astigmatism in our sample. There exists a
bias between the two devices and a systematic change with increased magnitude of
cylinder error. One possible explanation for the differences between Retinomax and
PeWE results could be the size of the pupil over which the two devices operate. In
this study we examined cycloplegic refractions, so wavefronts were measured over
large diameter pupils. Presence of higher order aberrations can affect the refraction
predicted by the wavefront sensor. Moving forward, we will analyze the effect of
pupil diameter on the PeWe measurements to determine which pupil size gives the
best correlation with the Retinomax.
CR: E.A. DeHoog, None; C.E. Clifford-Donaldson, None; E.M. Harvey, None; J.M.
Miller, None; V. Dobson, None; J. Schwiegerling, None.
Support: NIH Grant EY13153 (EMH) & Research to Prevent Blindness
Purpose: To extend our study of cognitive abilities of low-income preschool children
with uncorrected ametropia and the effects of spectacle correction at 6 weeks, and
examine the effects after 6 months.
Methods: Participants: 88 preschoolers (mean age=4.6 years; female=58.1%;
Latino=87.3%), sequentially recruited from the UCSD Eyemobile, 44 children with
previously uncorrected ametropia and 44 group-matched emmetropic controls.
Ametropia was determined by cycloplegic retinoscopy as bilateral hyperopia ≥ 4 D in
3 to 5-year olds, astigmatism ≤ -2 D in 3-year olds and ≤ -1.50 D in 4- and 5-year olds,
or a combination of both, and emmetropia as ≤2 D and ≥ -1 D in both eyes.
Procedure: The ammetropic group was assessed before, 6 weeks, and 6 months after
correction, and compared to the emmetropic controls. Compliance was monitored.
Design: Comparisons of change scores from baseline to 6-week and 6-month
reassessments between the ametropic and emmetropic groups.
Measures: Primary and secondary outcome measures were Beery-Buktenica
Developmental Test of Visual-Motor Integration (VMI) and Wechsler Preschool
Measure of Intelligence-Revised (WPPSI-R).
Statistical analysis: Repeated measures ANOVAs were performed. A group sequential
approach was applied to determine statistical power with 44 subjects per group at
6-week follow-up, and 22 subjects per group at 6-month follow-up.
Results: At 6-week follow-up with 44 subjects per group, the interaction on VMI became
highly significant, p < .005. The ametropic group did not improve significantly more
on WPPSI-R Performance Scale than the emmetropic controls, p = .35. At 6-month
follow-up with 22 subjects per group, an interaction was found on WPPSI-R, p = .007:
The ametropic goup improved 10.6 points, p < .001, compared to 2.7 points in the
emmetropic group, p = .18, resulting in an observed standardized effect size of 0.86
and a power of 0.79. The ametropic group was 9.15 times more likely to improve by
at least 5 points on both measures than emmetropic group.
Conclusions: These findings suggest that refractive correction resulted in gradual
improvement in visual motor integration related scores, beginning at 6-week followup and extending to 6 months.
CR: A. Roch-Levecq, None; B.L. Brody, None; R.G. Thomas, None; S.I. Brown,
None.
Support: Foster Fellowship in Vision & Development and Research to Prevent
Blindness
1428 - D639
Success Rate and Confidence Ratings of the Suresight Autorefractor for Testing
Infants and Young Children
1429 - D640
Video-See-Through Retinoscope for Optometric Training
C.E. Donaldson1A, V. Dobson1A,1B, T.K. Green1A, E.M. Harvey1A,1C. AOphthalmology and
Vision Science, BPsychology, CPublic Health, 1University of Arizona, Tucson, AZ.
Purpose: To determine success rates and examine confidence ratings of the SureSight
(SS, Welch Allyn) Autorefractor, as a function of age, in assessment of refractive
error in infants and young children from a Native American population with a high
prevalence of astigmatism.
Methods: Subjects were 956 children, aged 6 months to 8 years, recruited through
Women, Infants and Children (WIC) clinics, the Head Start Program, and K and 1st
grade elementary school classrooms on the Tohono O’odham Reservation between
2005 and 2007. Three non-cycloplegic right-eye SS (child mode) measurements were
attempted on each child. Results were grouped by age: 6 months to <1 year, 1 to <2
years, 2 to <3 years, 3 to <4 years, 4 to <5 years, 5 to <6 years, 6 to <7 years and 7 to
<8 years. Confidence ratings were categorized as <6 or ≥ 6 (the confidence rating
recommended by the manufacturer).
Results: On average, 2.7 measurements were obtained for each child and this number
did not vary by age. No measurement could be obtained for 5% of subjects. The
proportion of children for whom the confidence rating on the first measurement
was ≥ 6 ranged from 53.6% at 6 months to <1 year to 90% at 6 to <7 years and varied
significantly by age group (graph). Confidence ratings ≥ 6 on at least one of a maximum
of 3 readings ranged from 76.8% at 6 months to <1 year to 97.5% at 6 to <7 years and
varied significantly by age group (graph). Allowing 3 measurements significantly
improved the probability of obtaining a rating ≥ 6 in all age groups except 6 to < 7
years (ps < 0.05).
Conclusions: SS success rate in obtaining at least 1 measurement was high across
all age groups. Allowing 3 measurements significantly increased the likelihood of
obtaining a rating ≥ 6.
F. Vargas-Martin1A, P. Sobrado-Calvo1B. ADepartamento de Fisica, BDepartamento
de Oftalmologia, Optometria, Optometría, Otorrinolaringología y Anatomía
Patológica., 1Universidad de Murcia, Murcia, Spain.
Purpose: Retinoscopy is an invaluable technique to obtain an objective estimation of
the refractive error. The practitioner uses dynamic visual information and expertise
requires a lot of practice over time. Conventional retinoscopes do not have the
capabilities that would allow optometry instructors and students to view at the
same time.
Methods: An off-the-shelf video-see.through HMD system is attached to a commercial
retinoscope. A pinhole video camera is used as the vignetting observation pupil. The
video output was displayed in the HMD (to the instructor) and can be recorded and
visualized in real time as well as displayed on a video display for students to view.
Results: The instructor had the same that the students had at the same time, giving
importance to the reflex dynamics and case particularities.
The system was used in the initial practical course of the Optometry Degree at the
University of Murcia. Trainers filled a questionnaire for feedback. Lastly, videos of
practice demonstrations have been recorded.
Conclusions: The system has been considered as very useful in practical retinoscopy
training, and good video material is easily obtained for case reviews
CR: F. Vargas-Martin, None; P. Sobrado-Calvo, None.
Support: None
CR: C.E. Donaldson, None; V. Dobson, None; T.K. Green, None; E.M. Harvey,
None.
Support: NIH Grant EY13153 (EMH) and Research to Prevent Blindness
1426-1429
1430 - D641
A Comparison of the Marco/Nidek OPD, the Topcon Auto-refractor, and
Manifest Refraction in the Determination of Best Corrected Spectacle Visual
Acuity
1431 - D642
Personality and Tolerance of Blur
R.L. Woods1, C.R. Colvin2, F.A. Vera-Díaz1, E. Peli1. 1Schepens Eye Research Institute,
Boston, MA; 2Department of Psychology, Northeastern University, Boston, MA.
V.C. Fan, M. Massingale, M. Vallabhajosyula, P.A. Asbell. Ophthalmology, Mt Sinai
School of Medicine, New York, NY.
Background: Our practice environment employs several types of automated refractors.
Empirically, several clinicians feel that the Nidek OPD provides superior results as
compared to the other devices.
Purpose: To compare the accuracy of the Marco/Nidek ARK 10000 (OPD), the Topcon
KR3000 Autorefractor (AR) and Manifest Refraction (MR) in terms of sphere, cylinder,
and axis.
Design: Retrospective, observational case series in the Refractive Surgery Center in
the Department of Ophthalmology at the Mount Sinai School of Medicine.
Participants: 20 eyes of 10 healthy, adult patients eligible for refractive procedures with
refractive errors from -7.0D to +3.0D with a mean of -1.5D (as measured by MR)
Methods: Each patient underwent 3 automated measurements using the Marco/
NIDEK OPD ARK 10000 Scan as well as Topcon KR3000 during the same visit. We
recorded the mean of the sphere, cylinder, and axis. Subsequently, these measurements
were used as a base to formulate a MR measurement. None of the patients received
cycloplegic agents.
Main Outcome Measures: Difference in sphere and cylinder and axis of OPD compared
to MR and AR compared to MR. Differences of disparities between automated
measurements and MR in various ranges of refractive error.
Results: Repeatability analysis showed that the initial wavefront refraction was not
significantly different from the mean of the three refractions. The absolute value (±
standard deviation) of the difference between the initial OPD compared with the MR
was 0.46±0.48 diopters (D) for sphere, 0.21±0.26 D for cylinder, and 39.4±63.6 degrees
for axis; the difference between initial AR compared with the MR was 0.36±0.37
D for sphere, 0.31±0.33 D for cylinder, 24.9±48.5.for axis. However, the differences
between the OPD, the AR, and the MR for sphere, cylinder, and axis were not found
statistically significant.
Conclusions: The wavefront-derived OPD values reflect the physical optical system,
but not necessarily subjectively derived values, and the impact of this disagreement
on patient satisfaction is unknown. Although our clinical suspicion that the OPD was
superior to the other AR, our studies indicate that both the OPD and AR are similar
in estimating Refractive Error. Future studies with larger numbers evaluating these
and other technology and its role in clinical ophthalmology are warranted.
CR: V.C. Fan, None; M. Massingale, None; M. Vallabhajosyula, None; P.A. Asbell,
None.
Support: Martin and Toni Sosnoff Foundation
Purpose: To determine if tolerance to dioptric spherical defocus is related to measures
of personality. Clinical observations suggest that there is individual variability in
tolerance to blur, and some populations (e.g. older people) may be more tolerant.
Methods: A computer-controlled Badal optometer was used to measure “just-noticeable
blur” (depth of focus) and “objectionable blur” responses to positive lens defocus with
3.5mm, 4.5mm and natural pupils. Blur tolerance was defined as the difference between
the just-noticeable and objectionable blur responses while viewing three 20/50 highcontrast letters. A personality battery consisting of the NEO-PI-R and the California
Adult Q-sort (general measures of personality) and Perfectionism, Neuroticism, Highly
Sensitive Person, Ego-Resiliency, Need for Structure, and Negative Emotionality
scales (hypothesis driven measures) was administered using MediaLab software. One
hundred normally-sighted subjects (median 21, range 18 to 46 years; median refractive
error 0DS, range -5.87 to +2.75 DS) completed both aspects of the study.
Results: Within-subject blur tolerance measures with the three pupil sizes were highly
correlated (r = 0.88 to 0.92), implying good repeatability. There was a wide range
of individual blur tolerance. The personality questionnaires exhibited acceptable
reliability (Cronbach’s alpha = 0.67 to 0.91). Two perfectionism scales were significantly
correlated with blur tolerance. The 15 questionnaire items most highly correlated
with blur tolerance were factor analyzed and yielded two conceptually meaningful
factors (both alphas = 0.76). The “low self confidence” and “disorganization” factors
were positively correlated with blur tolerance (r = 0.38 and 0.36, respectively), and
their composite correlated with blur tolerance (r = 0.46). In the personality literature,
correlations of this magnitude are considered high.
Conclusions: These results provide initial evidence for a relationship between
personality and blur tolerance. It appears that people who lack self-confidence may
require strong evidence of blur before they have visual symptoms. Furthermore,
disorganized people may tolerate blur because it is simply another manifestation of
their untidy personal environments. Tolerance of blur may be related to perception
of image quality. If so, personality may influence refractive error correction and other
choices made when presented with degraded images.
CR: R.L. Woods, Johnson & Johnson Vision Care Inc., F; C.R. Colvin, Johnson &
Johnson Vision Care Inc., F; F.A. Vera-Díaz, Johnson & Johnson Vision Care Inc, F;
E. Peli, Johnson & Johnson Vision Care Inc., F; AMO, C.
Support: Johnson & Johnson Vision Care Inc.
1432 - D643
The Effects of Monocular Refractive Blur on Gait Parameters When Stepping
Up
1433 - D644
Blur Detection After Adaptation to Blurred and Clear Text in Myopic and
Emmetropic Young Adults
D.B. Elliott1A, A. Vale1A, J. Buckley1B. AOptometry, BMedical Engineering, 1University
of Bradford, Bradford, United Kingdom.
E.N. Harb, D. Kern, J.C. He, F. Thorn, J. Gwiazda. New England College of Optometry,
Boston, MA.
Purpose: Falls in the elderly are a major cause of mortality and morbidity. Elderly
people with visual impairment have been found to be at increased risk of falling,
with poor visual acuity in one eye causing greater risk than poor binocular visual
acuity. The present study investigated whether monocular refractive blur, at a level
typically used for monovision correction, would significantly reduce stereoacuity
and consequently gait parameters when negotiating a raised surface.
Methods: 14 healthy subjects (mean 25.8 years, SD 5.6) walked up to and on to a raised
surface, under four visual conditions; binocular, +2DS blur over their non-dominant
eye, + 2DS blur over their dominant eye and with their dominant eye occluded.
Analysis focussed on foot positioning and toe clearance parameters.
Results: Monocular blur had no effect on binocular acuity, but caused a small decline
in binocular contrast sensitivity and a large decline in stereoacuity (p<0.01). Vertical
toe clearance increased under monocular blur or occlusion (p<0.01) with a significantly
greater increase under blur of the dominant eye compared to blur of the non-dominant
eye (p<0.01). Increase in toe clearance was facilitated by increasing maximum toe
elevation (p<0.01).
Conclusions: Findings indicate that monocular blur at a level typically used for
monovision correction significantly reduced stereoacuity and consequently the ability
to accurately perceive the height and position of a raised surface placed within the
travel path. These findings may help explain why elderly individuals with poor visual
acuity in one eye have been found to have an increased risk of falling.
CR: D.B. Elliott, None; A. Vale, None; J. Buckley, None.
Support: College of Optometrists studentship; RCUK academic fellowship
Purpose: Adaptation to blurred images makes images appear relatively sharper
and adaptation to clear images has the opposite effect. Compared to emmetropes,
myopes have been shown to exhibit better visual performance with blurred stimuli
and greater adaptation to blur. The aim of this study is to determine if differences
exist between stable myopes’ and emmetropes’ blur detection thresholds at baseline
and following adaptation to blurred and clear text.
Methods: 21 stable myopes (mean±sd: -4.38±2.28 D) and 15 emmetropes (mean±sd:
0.23±0.33D) aged 22-34 years were best corrected and viewed a passage of text on a
computer monitor at 33 cm in order to measure: (1) baseline blur detection thresholds
and (2) thresholds after adaptation to blurred or clear text. Blurring of the stimulus text
was generated by the application of a pseudo-Gaussian filter. A double randomized
staircase procedure was used to determine blur thresholds. The order of blur and
clear adaptation was random. Descriptive statistics and t-tests for differences between
conditions and refractive groups were used.
Results: Stable myopes and emmetropes had similar thresholds at baseline (mean±sd
for myo vs emm: 0.47±0.10 vs 0.49±0.06), but higher myopia was correlated to lower
thresholds (R=0.34;p<0.05). Myopes and emmetropes had similar thresholds after
blur adaptation (mean±sd for myo vs emm: 0.07±0.10 vs 0.03±0.07; p=0.12) and clear
adaptation (mean±sd for myo vs emm: -0.27±0.08 vs -0.27±0.06; p=0.93). Blur thresholds
changed significantly more from baseline following clear adaptation compared to
blur adaptation (p<0.005).
Conclusions: Blur detection thresholds before and after adaptation to blurred or clear
text is similar between stable myopes and emmetropes. However, higher stable myopia
is related to lower thresholds at baseline. Adaptation to clear images appears to be
more robust than adaptation to blurred images, regardless of refractive error.
CR: E.N. Harb, None; D. Kern, None; J.C. He, None; F. Thorn, None; J. Gwiazda,
None.
Support: NIH/NEI R01 EY01191
1430-1433
1434 - D645
Neural Contribution to the Mesopic Acuity Deficit in Myopia
1435 - D646
Enhancement of Under Corrected Visual Acuity and Contrast Sensitivity
in Myopic Children Using NeuroVision’s Neural Vision Correction (NVC)
Technology
N.J. Coletta, A. Raghuram, T. Nguyen, M. Rondon. Vision Science, New England
College of Optometry, Boston, MA.
Purpose: Myopes experience a greater loss in acuity with decreasing luminance than
emmetropes (Coletta et al., ARVO, 2007). Optical and neural factors may contribute
to this effect, since myopic eyes are reported to have lower optical quality than
emmetropic eyes and the axial elongation of myopic eyes is associated with retinal
stretching that may increase the spacing of retinal neurons. Retinal illumination
should also be decreased in eyes with increased axial lengths. We measured acuity
at a low mesopic light level with interference fringes that minimize the effect of the
eye’s optical quality, in order to better estimate the effects of retinal illumination and
possible neural contributions to mesopic acuity in myopia.
Methods: Measurements were made on twenty-three subjects who had 20/25 or
better spectacle-corrected acuity for a photopic high contrast acuity chart. Spherical
equivalent refractions ranged from plano to -8.25 D. The retinal magnification factor
(RMF; mm/deg) for each eye was estimated from corneal topography and IOLMaster
biometry of anterior chamber depth and axial length, and the RMF was used to convert
acuity in angular units of cyc/deg to retinal units of cyc/mm. Interferences fringes
were 543nm and had a mean retinal illuminance of 0.1 troland. After 15 minutes of
dark adaptation, a two-alternative forced choice vertical-horizontal discrimination
task was used to estimate the fringe acuity limit.
Results: Mesopic interferometric acuity significantly decreased with increasing
myopia at a rate of 0.025 log unit per diopter of myopia (p=0.029). This rate is steeper
than the rate of about 0.013 log unit per diopter previously published for photopic
interferences fringes (Coletta and Watson, 2006; Atchison et al., 2006). When acuity
was plotted against axial length, mesopic interference fringe acuity fell at a rate of
about 0.067 log unit per mm increase in axial length (p=0.028). This slope is steeper
than the comparable data for photopic interferometric acuity (0.03 log unit per mm)
and much steeper than the prediction based on decreased retinal illumination, which
is about 0.01 log unit per mm (based on a change of acuity of 0.25 log unit per log
unit change in illumination).
Conclusions: Mesopic interferometric acuity decreases with increasing myopia and
axial length at rates that are steeper than those observed at photopic light levels.
These results imply that factors other than decreased retinal illumination and optical
quality affect visual acuity in myopia.
CR: N.J. Coletta, None; A. Raghuram, None; T. Nguyen, None; M. Rondon, None.
Support: NIH Grants R24 EY014817 and T35 EY007149
1436 - D647
A Randomized Controlled Trial Evaluating the Efficacy of Neurovision’s Neural
Vision CorrectionTM Technology in Enhancing Unaided Visual Acuity in Adults
With Low Myopia
M. Jamil, A. Fong, D. Tan. Singapore Eye Research Institute, Singapore, Singapore.
Purpose: To evaluate the efficacy of NeuroVision’s Neural Vision Correction™ (NVC™)
Technology in enhancing unaided visual acuity in adults with low myopia.
Methods: NeuroVision’s NVC™ technology is a non-invasive, patient-specific,
perceptual learning program based on visual stimulation and facilitation of neural
connections at the cortical level. It involves an internet-based computer generated
visual training exercise regime using stimuli based on Gabor patches, to sharpen
contrast sensitivity and visual acuity. A double masked randomized controlled trial
was conducted to evaluate the efficacy of NVC™ technology in improving unaided
visual acuity (UAVA) of low myopic patients. 84 adult low myopic patients (LMP) with
SE ≤ -1.5D (mean SE -1.29D) were randomly divided into 2 groups. Group A (66 LMP)
completed NVC™ treatment, Group B (18 LMP) completed sham treatment.
Results: Mean UAVA improved by 0.186 logMar in Group A compared to 0.023 logMar
in Group B. 65.2% of LMP in group A improved more than 0.2 logMar in at least
one eye compared to 11.1% in Group B (p<0.0005). Mean refractive error remained
unchanged.
Conclusions: NVC™ treatment demonstrated statistically significant UAVA
improvement in adults with low myopia.
CR: M. Jamil, None; A. Fong, None; D. Tan, None.
Support: None CT: www.clinicaltrials.gov, NCT00348075
K. Ian1, D. Tan2,3, A. Fong2,3, W. Chua2,3. 1R & D Dept, Essilor R & D Centre Singapore,
Singapore, Singapore; 2Singapore National Eye Centre, Singapore, Singapore;
3
Singapore Eye Research Institute, Singapore, Singapore.
Purpose: NeuroVision’s NVC™ technology is a non-invasive, patient-specific,
perceptual learning program based on visual stimulation and facilitation of neural
connections at the cortical level, involving an internet-based computer generated
visual training exercise regime using stimuli based on Gabor patches, to sharpen
contrast sensitivity and visual acuity. Children with highly progressive Myopia often
use under-corrected eyeglasses, due to: improper prescription, intentional undercorrection or simply due to the high progression of their Myopia. We evaluated the
efficacy of NVC treatment in the enhancement of under-corrected visual acuity (UCVA) and contrast sensitivity function (UC-CSF) in Myopic children in Singapore.
Methods: 33 children aged 7-9 having a myopia refraction of at least -1.0DS in both
eyes (mean cycloplegic SE of -2.88D, range -1.0D to -6.00D) completed NVC treatment
over a period of 3-4 months. During the course of treatment, subjects were prescribed
with eyeglasses that are 0.5D under their full manifest refraction.
Investigations included manifest and cycloplegic refraction, axial length measurements,
Under-Corrected (1.0DS) VA and CSF
Results: Mean UC-VA before treatment was 0.47 logMar, improving by 0.22 logMar to
0.25 post treatment. UC-CSF at 1.5, 3, 6, 12, 18 cpd improved as well from 40, 43, 30, 8,
2.5 at baseline to 70, 110,100, 35, 12 at the end of the treatment. Changes in cycloplegic
refraction (-0.47D) and Axial length (0.177mm) were within the expected Myopia
progression for this age group.
Conclusions: Results of the NVC treatment suggest that this technology is able to
improve under-corrected VA and CSF in Myopic Children. The long-term implication
on Myopia progression is now under investigation.
CR: K. Ian, Essilor, E; D. Tan, None; A. Fong, None; W. Chua, None.
1437 - D648
Analysis of Visually Triggered Micro-Saccades Measured With the Orbscan
R. Kopito, S. Sancho, A. Leseigneur, E. Costantini, T. Gaujoux, O. Touzeau, C. Allouch, L.
Laroche. CHNO des Quinze-Vingts, Paris, France.
Purpose: To analyze the ocular micro-saccades and to establish their correlation with
the biometric and refractive parameters of the eye.
Methods: The micro-saccades of 120 healthy eyes of 60 volunteers (mean age 37 years
± 16, range 19-81) including ametropia were prospectively recorded with the Orbscan
device using the software “Track Eye Movement”. The properties of the saccades
including mean movement and rate were analyzed and correlated to the biometric
and refractive parameters including axial length, anterior chamber depth, corneal
curvature, pachymetry, spherical equivalent, astigmatism and visual acuity. The
axial length was measured with A-scan ultrasound and the biometry of the anterior
segment with the Orbscan topography system. The difference between two successive
measurements was calculated to determine the reproducibility.
Results: The reproducibility of the measurements of the saccades was 25% for the
average movement and 21% for the average rate. The movement and rate of the saccades
did not differ from the fellow eye (p ≥ 0.36) and were correlated significantly with
the fellow eye (rs ≥ 0.49; p < 0.001). In addition they were correlated to the spherical
equivalent (rs ≥ 0.20; p < 0.015) and the axial length of the eye (rs ≥ -0.17; p < 0.03).
However the properties of the micro-saccades were not significantly influenced by
astigmatism, BSCVA, sex and age (p ≥ 0.05).
Conclusions: Visually triggered saccades of myopic eyes and great axial length turn
out to be slower and smaller than those of hyperopic eyes and short axial length. A
deeper understanding of ocular saccades could be of clinical interest particularly for
the improvement of eye-tracking-systems in the field of refractive surgery, but also
diagnostically for topographic systems such as the Orbscan device.
CR: R. Kopito, None; S. Sancho, None; A. Leseigneur, None; E. Costantini, None; T.
Gaujoux, None; O. Touzeau, None; C. Allouch, None; L. Laroche, None.
Support: None
1434-1437
1438 - D649
Measurement of the Real Size of Fundus Objects With the Retina-StripeProjector (RSP)
1439 - D650
Refraction Changes in Different Artificial Vitreous Body Tamponade Eyes
Based on Gullstrand-Emsley Schematic Eye
J. Dawczynski1, T. Mohr2, I. Koschmieder2, B. Rassow3, A.-K. Schubert2, T. Ach1, J. Strobel1.
1
Ophthalmology, University Hospital Jena, Jena, Germany; 2Carl Zeiss Meditec
AG, Jena, Germany; 3Experimental Ophthalmology, University Hospital Hamburg,
Hamburg, Germany.
Q. Gao, X. Chen, J. Ge, Z. Lin. State Key Lab of Ophthalmology, Zhongshan
Ophthalmic Center, Guangzhou, China.
Purpose: To test and to measure the real size of human fundus objects with the
Retina-Stripe-Projector (RSP, Carl Zeiss Meditec, Jena, Germany).
Methods: Fundus images were taken from 52 eyes with the RSP (based on an
interferometer of Baumbach). Distances between stripes were calculated according to
the method of Littmann (influenced by the curvature of the cornea and ammetropia)
and measured with the RSP.
Results: Calculated object size with Littmann method showed a ±5.47% (0.01 - 13.63%)
difference in comparison to measured object size with RSP. In 51 of 52 eyes measured
object size was smaller than calculated size by the Littmann method. In cases with
non-axial ammetropia differences between both methods were more considerable
compared to eyes with ammetropia caused by axial length. By using the corrected
Littmann formula respecting the axial length, the difference between calculated and
measured object size may be reduced to nearly 1%.
Conclusions: Fundus object size calculation by the Littmann method should be
corrected in cases of non axial length ammetropia. A considerable improvement of
the measured object size compared to the calculated object size may be reached by
using the axial length as a further correction factor.
CR: J. Dawczynski, None; T. Mohr, Carl Zeiss Meditec AG, E; I. Koschmieder, Carl
Zeiss Meditec AG, E; B. Rassow, None; A. Schubert, Carl Zeiss Meditec AG, E; T.
Ach, None; J. Strobel, None.
Support: None CT: University of Jena, 1959-02/07
1440 - D651
Lack of Refraction Changes During Acute Hyperglycemia in Healthy Young
Persons
Purpose: To determine the refraction in different artificial vitreous body tamponade
eyes including silicone oil, heavy silicone oil, and polymeric gels after pars plana
vitrectomy (PPV) surgery with Gullstrand-Emsley schematic eye.
Methods: The optical constants of artificial vitreous body -filled eyes were calculated
based on No.1 Gullstrand-Emsley schematic eye with accommodation relaxed. The
theoretical refraction was calculated in PPV alone and PPV plus lensectomy eyes after
silicone oil, heavy silicone oil, and polymeric gels tamponade.
Results: The theoretical refractions show a refractive shift of +8.93D, -6.29D and
+0.23D in the PPV treated eyes, and of +11.33D, +20.71D, +16.73D in the PPV plus
lensectomy treated eyes in silicone oil, heavy silicone oil, and hydrogels tamponade
eyes, respectively. Conclusions: The mathematic method by Gullstrand-Emsley
schematic eye is useful for prediction the refraction changes in various artificial
vitreous tamponade eyes.
CR: Q. Gao, None; X. Chen, None; J. Ge, None; Z. Lin, None.
Support: the Science and Technology Foundation of Guang Dong Province of China
(06104574) and the Science and Technology Foundation of Guang Zhou City of China
(2006Z2-E0141).
1441 - D652
Comparison of Myopia Induced by Retrodots and Nuclear Cataract
P. Jeppesen1A, S.T. Knudsen1B, P.L. Poulsen1B, C. Mogensen1B, O. Schmitz1B, T. Bek1A.
A
Ophthalmology, BMedical Dept. M (Diabetes and Endocrinology), 1Aarhus Univ
Hospital, Aarhus, Denmark.
Purpose: To study refraction changes in eyes from healthy persons during
hyperglycemia.
Methods: In a randomized, double-blinded cross-over study nine healthy persons
were subjected to clamping of blood glucose to either euglycemia (5 mmol/l) or
hyperglycemia (15 mmol/l) using somatostatin to control the endogenous insulin
secretion. Each person was studied on two days: On one day euglycemia (E) was present
throughout the day during two rounds of measurements of optical parameters were
performed, including corneal thickness, anterior chamber depth, lens thickness, and
axial length were measured using corneal pachymetry and ultrasound biometry. On
the other study day similar examinations were performed, but hyperglycemia (H) was
induced after the first round of measurements of optical parameters.
Cycloplegia was obtained using topical cyclopentolatehydrochloride (Cyclogyl
1%,Alcon,USA) administered to the study eye one hour prior to the first
measurement.
Results: Hyperglycemia did not induce significant changes in any of the measured
optical parameters. A significant increase in lens thickness was observed during
euglycemia, from 3.60mm to 3.68mm (p=0.01) on the right eye, and from 3.64mm to
3.67mm (p=0.03) on the left eye. In parallel with this a non-significant decrease in
hypermetropia was found, from 0.60DS to 0.39DS (p= 0.13) on the right eye and from
0.68DS to 0.44DS (p=0.12) on the left eye. None of the other measured parameters
showed significant changes during the experiment.
Conclusions: Diurnal changes in lens thickness are suppressed by hyperglycemia.
Refraction changes in diabetic patients may be due to other factors than changes in
blood glucose.
CR: P. Jeppesen, None; S.T. Knudsen, None; P.L. Poulsen, None; C. Mogensen,
None; O. Schmitz, None; T. Bek, None.
Support: None
N. Fujita1A, H. Sasaki1A,2, Y. Sakamoto1A,2, M. Kojima1A,2, J. Qu1A, N. Yamamoto1A, Y.
Kawakami1A, K. Nagai1A, H. Nakaizumi1A, K. Sasaki1B. AOphthalmology, BDivision
of Vision Research for Environmental Health, 1Kanazawa Medical University,
kahoku-gun, Japan; 2Division of Vision Research for Environmental Health,
Kanazawa Medical University, Kahoku-gun, Japan.
Purpose: It is well known that some nuclear cataract cause myopic sift of refraction,
but we found that Retrodots would also lead to myopia at some level. In this study, we
compared the influence of Retrodots (RD) and nuclear cataract on ocular refraction.
Methods: 246 cases (444 eyes) who participated in the Monzen Eye Study in 2005
or who received cataract surgery in Kanazawa Medical University Hospital from
December 2005 to March 2007were examined retrospectively. Cases with cortical
opacity within 3mm diameter of the pupil and posterior subcapsular cataract were
excluded. RD was classified into five steps according to the occupancy of the opacity.
Nuclear cataract was also graded into four steps by the WHO classification system.
Axial length was measured by an A-mode Ultrasound (AL2000,TOMEY). An Auto
Kerato-Refractometer (ARK. NIDEK) was used to compute refraction. Lens reflective
power was calculated on SPK.
Results: There was no significant difference in axial length and reflection between the
steps. The averages of reflection of RD step 0 to 4 were 0.67D, 0.80D, 0.59D, -0.85D and
-0.43D. The average lens refractive power were 17.50D, 17.45D, 16,98D, 19,69D, 18.86D,
then we found a remarkable tendency of myopia and increase of lens refractive power
(p<0.05). The mean scores of reflection of each nuclear cataract step 0 to 3 were 0.67D,
0.47D, -1.95D, -3.53D, and average lens refractive power were 17.50D, 17.86D, 21,62D
and 23,97D. There were also significant myopic tendency and growth of refractive
power (p<0.01). The average lens refractive power of complicated cases of over step3
RD and over step2 nuclear cataract were 24.00D, and the average refraction of the
cases was -3.59D.
Conclusions: Nuclear cataract is more influential on refraction than RD. Still
Nuclear cataract and RD often result in a complication, and make myopia advance
seriously.
CR: N. Fujita, None; H. Sasaki, None; Y. Sakamoto, None; M. Kojima, None; J. Qu,
None; N. Yamamoto, None; Y. Kawakami, None; K. Nagai, None; H. Nakaizumi,
None; K. Sasaki, None.
Support: None
1438-1441
Monday, April 28, 11:15 AM - 1:00 PM Palm A Paper Session Program Number Range: 1507-1513
231. Impaired Vision: Phenomena, Fixation, and Function Organizing Section: VI Contributing Section: CO
1507 - 11:15AM
Fixation Stability Measurement Using the MP1 Microperimeter: A Method to
Improve the Quantification of Results
1508 - 11:30AM
Smooth Estimation of Visual Field Loss for Predicting Function
M.D. Crossland1A, H.M.P. Dunbar2, G.S. Rubin1A,1B. AVision Rehabilitation, BNIHR
Faculty, 1UCL Institute of Ophthalmology, London, United Kingdom; 2Optometry,
Moorfields Eye Hospital, London, United Kingdom.
Purpose: The Nidek microperimeter (MP1, Nidek Instruments, Italy) is a recently
available clinical perimetry device which also assesses fixation stability. The MP1
expresses fixation stability in three ways: (i) as a fixation score (stable, relatively
unstable, or unstable); (ii) as the proportion of fixations falling within the central 2º
of retina; and (iii) as the proportion of fixation points falling within the central 4º
of retina. In most published research, fixation stability is quantified by calculating
a bivariate contour ellipse area (BCEA) which encompasses 68% of fixation points.
Here we compare these four methods of fixation assessment (Fixation Score, Central
2º, Central 4º, BCEA) by correlating them to various parameters of reading known to
be related to fixation stability.
Methods: Twenty-three people with age-related macular disease were assessed. Eye
position was recorded at 25Hz using the MP1 whilst patients performed a perimetry
task. Fixation score, central 2º and central 4º values were obtained from the MP1’s
inbuilt software. BCEA values were calculated from raw fixation data extracted
from the MP1. Reading speed was assessed using MNREAD, Rapid Serial Visual
Presentation (RSVP) and EUREAD tests.
Results: No relationship was revealed between any reading parameters and the MP1
fixation score, the Central 2º value or the Central 4º value (p>0.1 for all comparisons). In
contrast, there was a significant relationship between fixation stability assessed using
the BCEA technique and RSVP reading speed (r=0.59, p<0.01), EUREAD reading error
rate (r=0.66, p<0.01), and MNREAD peak reading speed (r=0.55, p<0.05).
Conclusions: Using the software supplied with the MP1 does not adequately
quantify fixation stability in people with age-related macular disease. However, a
straightforward post-hoc analysis of the raw fixation data from the MP1 can be applied
to detect subtle yet important differences in fixation stability between subjects. We
suggest that this technique is used in studies where change in fixation stability is of
importance, such as in clinical trials.
CR: M.D. Crossland, None; H.M.P. Dunbar, None; G.S. Rubin, None.
Support: Grant from the Macular Disease Society, UK
L.L. Renninger, C. Psomadakis, L. Dang, D. Fletcher. Smith-Kettlewell Eye Research
Institute, San Francisco, CA.
Purpose: It is not well understood how the profile of central field loss due to macular
degeneration leads to differential difficulties in activities of daily living. The coarse
nature of clinical field assessment may contribute variability to the data, obscuring
potential links between field loss and functional losses. In this work, we develop an
algorithm to generate field maps from which scotoma metrics can be computed.
Methods: Microperimetry was performed on low vision patients using a scanning
laser ophthalmoscope (SLO). Continuous scotoma maps (SM) were estimated from
this discrete data using a weighted k-nearest neighbor classification algorithm (figure).
The weights are varied as a function of eccentricity from the fovea, whose location is
defined relative to the optic disk. The preferred retinal locus (PRL) was taken as the
location of the fixation cross during microperimetry. Scotoma metrics were estimated
including: distance from fovea to PRL, total area and location of scotoma relative to
PRL, and shape/symmetry of scotoma. The metrics were validated against a clinical
assessment. Correlations were computed between scotoma metrics and functional
tests such as acuity, fixation stability and reading rates.
Results: The distance from the foveal location to the PRL was correlated with acuity
(0.57), however not with scotoma area, suggesting that scotoma are not typically
symmetric about the fovea. Accordingly, no significant correlation was found between
scotoma area and acuity. Previous results (Fletcher & Schuchard, 1999) found that
acuity was a weak predictor of reading rates (-0.47 in this data). Scotoma area was a
slightly stronger predictor (r=-0.54).
Conclusions: The correlation of acuity and scotoma area with reading rates is expected,
however the lack of correlation between these two measures suggests they may affect
reading behavior through different mechanisms. In related work (Renninger, et.
al., VSS 2008), the efficiency of eye movements in a shape discrimination task were
drastically affected as scotoma area increased. While poor acuity may hinder letter
and word recognition, large scotomas likely hinder saccadic targeting of the text.
CR: L.L. Renninger, None; C. Psomadakis, None; L. Dang, None; D. Fletcher,
None.
Support: NIH R01 EY018004; Pacific Vision Foundation
1509 - 11:45AM
The Two-Dimensional Shape of Spatial Interaction Zones at the PRLs of
Observers With Central Vision Loss
1510 - 12:00PM
Quantifying the Effect of Illumination on Visual Acuity and Contrast
Sensitivity in Low Vision Patients
S.T.L. Chung, Y. Lin. College of Optometry, University of Houston, Houston, TX.
I.L. Bailey1, A. Jackson2, J. Zwelling1, R.B. Greer1. 1School of Optometry, University of
California, Berkeley, Berkeley, CA; 2Ophthalmology and Optometry, Royal Victoria
Hospital, Belfast, United Kingdom.
Purpose: Patients with long-standing central vision loss often adopt a peripheral
retinal location (the preferred retinal locus, PRL) as the locus for oculomotor and
other visual tasks. Our previous work hinted that the PRL might exhibit properties
resembling those of the normal fovea instead of the normal periphery as a result of
adaptation. Here, we tested whether or not the properties of the spatial interaction
zone measured at the PRL resemble those of the normal fovea or the periphery.
Methods: Spatial interaction zones were determined for five observers (age: 48 - 83,
logMAR acuity: 0.46 - 0.98) with long-standing central vision loss by measuring the
extent of spatial interaction along four meridians (0, 45, 90 and 135° from horizontal)
with respect to each observer’s PRL. Stimuli were random sequences of three uprightoriented lowercase letters projected on the retina of the eye with better vision using
a Rodenstock scanning laser ophthalmoscope (SLO). For each meridian, we used a
staircase procedure to track the center-to-center separation between the middle target
letter (at a fixed retinal location) and its flankers that yielded 71% correct for identifying
the target letter. The retinal location of each observer’s PRL was determined from
the SLO images for the correct trials (with the stimuli superimposed on the fundus),
assuming that the target letter was centered on the PRL. For comparison, we also
measured the spatial interaction zone at the fovea and 10° lower field in a group of
11 age-matched observers with normal vision.
Results: Consistent with previous studies, the size of the spatial interaction zone is
larger at 10° lower field than at the fovea for observers with normal vision, and that
the shape of the interaction zone is elongated vertically at 10° lower field such that the
ratio between the major and minor axes of the zone was 1.7. For observers with central
vision loss, the PRLs clustered around the vertical meridian and located between 2.5
and 7.7° from the anatomical fovea. The sizes of the spatial interaction zones centered
on the PRLs were similar to the predicted values at the same retinal eccentricities
in the normal periphery; however, the shape of the interaction zone became circular
instead of elliptical (averaged ratio between the major and minor axes = 1.1).
Conclusions: The circular instead of elliptical shape of the spatial interaction zones
obtained at the PRLs of observers with central vision loss suggests that the shape of
the interaction zone resembles closer that of the normal fovea instead of the normal
periphery, indicating that the PRL might have undergone adaptive changes with
time to become more fovea-like.
CR: S.T.L. Chung, None; Y. Lin, None.
Support: NIH grants R01-EY12810 and P30-EY07551
Purpose: Low vision patients frequently have extra-ordinary responses to changes in
task luminance. Clinicians typically rely on history taking and the patients’ reports of
their visual experience when changes are made to the quality or quantity of lighting.
We have identified an easy-to-administer method for quantifying individual patients’
responses to changes in light levels, which involves the measurement of visual acuity
and contrast sensitivity with and without a standard neutral gray filter.
Methods: Subjects are recruited from the Low Vision Clinic of the School of Optometry
at UC Berkeley. Visual acuity measurements are made with a retro illuminated BaileyLovie Chart at a test distance of 3 or 4 meters. Contrast sensitivity is measured using
a computer-based test in which the subject is required to locate a large blinking
square (about 5 degrees) that appears in one of four marked quadrants. The touch
screen provides a measure of response time as a function of target contrast. These
measurements are made with and without a NOIR U23 neutral-gray filter. This widely
available fit-over sunglass filter has a 1.8 ND. Thus we determine the magnitude of
the increase or decrease in VA and CS in response to a standard reduction (to 1.6%)
in retinal illuminance.
Results: Normally sighted subjects show, on average, a 0.22 log unit reduction (11
letters) in visual acuity and a 0.13 log unit reduction (25%) in contrast sensitivity. Within
low vision patients having the same diagnosis, there can be considerable diversity,
but some strong patterns emerge. Compared to normals, glaucoma patients show
about the same reduction in VA (0.23 log units) but twice the reduction in CS (0.27),
RP patients show more pronounced reductions in both visual functions, particularly
for CS. On the other hand, patients with albinism generally do not show much change
in acuity but have moderate reductions in CS. AMD patients show more change than
normals and this is can be most pronounced for visual acuity. Some patients show a
visual improvement with the filter.
Conclusions: Low vision patient responses to reductions in illumination can be
characterized quantitatively by measuring VA and CS with and without a dense
neutral filter. This information can be obtained quickly, simply and with minimal
expense, and it can be useful in guiding the clinician’s treatment decisions and
prediction of functional abilities.
CR: I.L. Bailey, None; A. Jackson, None; J. Zwelling, None; R.B. Greer, None.
Support: None
1507-1510
Monday, April 28, 11:15 AM - 1:00 PM Palm A Paper Session Program Number Range: 1507-1513
231. Impaired Vision: Phenomena, Fixation, and Function Organizing Section: VI Contributing Section: CO
1511 - 12:15PM
Visual and Cognitive Function Predict the Likelihood of Restricting or
Stopping Driving: The Salisbury Eye Evaluation and Driving Study (SEEDS)
1512 - 12:30PM
Speed Discrimination: Effects of Age and Age-Related Macular Degeneration
L.J. Keay1A,2, B. Munoz1A, K. Turano1A, S. Hassan1A, C. Munro1B, K.J. Bandeen Roche1C,
S.K. West1A, SEEDS Project Team. AWilmer Eye Institute, BPsychology and Behavioral
Sciences, CBiostatistics, School of Public Health, 1Johns Hopkins University,
Baltimore, MD; 2Injury and Musculoskeletal Division, George Institute for
International Health, University of Sydney, Sydney, Australia.
Purpose: to explore the factors which are predictive of stopping or restricting driving
in older drivers.
Methods: We enrolled 1425 drivers aged 67-87, who were residents of greater Salisbury
from the Maryland Department of Motor Vehicles roster at baseline. We selected all
those who reported driving beyond their neighborhood. At one year post enrollment,
we categorized this group into those who stopped driving, those who no longer drove
beyond their local neighborhood and those who continued to drive beyond their local
neighborhood. Change in miles driven in 5-day on road assessments were compared
between groups. Multivariate analysis determined the demographic, visual and
cognitive factors predictive of stopping or reducing driving.
Results: Of the 1425 licensed drivers enrolled, mean age was 75±5, 50% male. A total
of 1237 or 87% were interviewed and/or had driving assessment at one year. Those
already limiting their driving at baseline were excluded (n=35). At follow-up, 1.5%
(18/1202) had stopped and 3.4% (41/1202) restricted their driving. Those who limited
their driving had an average decrease of 40±96 miles (5-day odometer readings)
to on average 5 miles/day while those not limited, reduced 6±106 miles and drove
approximately 20 miles/day at follow-up. In the multivariate model, males were
less likely to stop or restrict driving (OR 0.19, 95% CI 0.09-0.40). Those with higher
cognitive function were also less likely (0.83, 0.70-0.98 per point Mini-Mental State
Examination). Depressive symptoms increased (OR 1.09, 1.02-1.17 per point General
Depression Score) likelihood of restricting or stopping driving. Baseline visual acuity
predicted stopping or reducing driving (OR 1.16, 1.03-1.51, per line lost) and good
contrast sensitivity was marginally associated with decreased likelihood of stopping
or reducing driving (OR 0.88, 0.77-1.01 per letter seen). Visual field loss and visual
attention were not associated with driving changes.
Conclusions: In this cohort, visual acuity and cognitive function were independently
associated with incident cessation or restriction of driving space. However, other
factors such as depressive symptoms are also predictive of future change in driving
habits.
CR: L.J. Keay, None; B. Munoz, None; K. Turano, None; S. Hassan, None; C. Munro,
None; K.J. Bandeen Roche, None; S.K. West, None.
Support: AG23110, NHMRC Post Doctoral Research Fellowship (LK)
J.V. Odom, M. Leys. Ophthalmology and Physiology and Pharmac, West Virginia
Univ Eye Institute, Morgantown, WV.
Purpose: To determine the thresholds for speed discrimination in three groups of
subjects, young normals, older normals, and patients with central visual field loss
due to age-related macular degeneration (AMD).
Methods: Three groups of observers made speed discrimination judgments. The
groups were younger normals aged 21-50 years, older normals aged =>60 years and
low vision patients with AMD aged =>60 years. Observers were seated 50 cm from
a display that subtended 44.6 arc deg in the horizontal dimension. Pressing a mouse
began a trial. During the 833 mS trial, a pattern of 100 white dots on a black background
appeared. The observer saw four regions on the screen. Alternating regions of the
screen moved in opposite directions, 25 dots in each region, at random locations and
moved either left to right or right to left. Dots had a lifetime of 467 mS or were replaced
as they moved off of the screen. The observer’s task was to determine the direction
of motion which had faster moving dots.
Results: AMD patients discriminate speed differences less well than younger normals
(p<0.01) and tended to discriminate speed differences less well than older normals
as well, although the difference was not statistically significant. There was also a
trend for the older normals to discriminate speed differences less well than younger
normals.
Conclusions: The results are consistent with Brown et al. (1986) who reported that
discrimination of speed differences was related to mobility performance in low vision
patients. The untested implication from our results is that AMD patients would have
impaired mobility performance.
CR: J.V. Odom, None; M. Leys, None.
Support: NIH Grant EY 14841
1513 - 12:45PM
Low Vision Access to the Web via a Firefox Browser Extension
A. Arditi, J. Lu. Arlene R Gordon Research Institute, Lighthouse International, New
York, NY.
Purpose: The Internet and in particular the World Wide Web, are increasing availability
of information for everyone with access to them, but they especially have the
potential to improve the lives of persons with low vision, perhaps more than any
other technological development in history. Accessible and convenient technology
for those with moderate and severe low vision.has remained problematic. Those users
must rely on specially authored web sites or on expensive, platform-specific, and
non-portable software solutions. We have developed browser extension technology
for the Mozilla Firefox browser (eventually to be ported to Internet Explorer as well)
specifically designed for users with low vision to access differently authored web
pages in a consistent way.
Methods: Our software utilizes a transcoding design that intercepts web page markup
documents on input to the browser’s rendering engine, analyzes it, alters it, and then
re-renders it in two distinct frames: a top frame for reading, and a bottom “global”
frame for navigating and appreciating global layout. When the (large) cursor hovers
over text in the global frame, that text is displayed in the reading frame (which supports
hyperlinks), at a single format tailored to the user’s needs. If the text string is too long
to fit within a single line of the reading frame, the string is broken, and successive
portions of the string are elicited, by means of the down-arrow key press, so that the
reader can key through the entire screen at his or her own pace, a practice that has
been shown to enhance reading performance with sequential word presentation.The
size, background and all aspects of typography and color contrast of the text in the
reading frame are configurable. In general, once the user has found optimal settings
such as font color, font size, font style and background color, they will likely use them
to read all web content, so persistent storage of user settings is supported. Embedded
images may also be selected and magnified.
Results: The browser extension is open source, free, and has a very simple and intuitive
user interface. It can be installed on a memory stick, or downloaded and installed on
demand from any location.
Conclusions: Our software, called LowBrowseTM, provides no-cost, portable access
to the web for all users with low vision.
CR: A. Arditi, None; J. Lu, None.
Support: NIH grants EY01592 and EY017583
1511-1513
Monday, April 28, 11:15 AM - 1:00 PM Hall B/C Poster Session Program Number/Board # Range: 1788-1800 / D653-D665
250. Accommodation and Depth of Focus Organizing Section: VI
1788 - D653
A Comparison Between Objective Depth-Of-Focus and Subjective Depth-OfFocus
1789 - D654
Correction of Aberration Dynamics Modulates Closed-Loop Accommodation
Responses in a Time Dependent Manner
B.-C. Jiang1, H. Lin2. 1Coll of Optometry, Nova Southeastern University, Fort
Lauderdale, FL; 2Optometry School, Wenzhou Medical College, Wenzhou, China.
K.M. Hampson, S.S. Chin, E.A.H. Mallen. Optometry, University of Bradford,
Bradford, United Kingdom.
Purpose: To compare the depth-of-focus (DOF) measured with objective and subjective
methods.
Methods: Twelve emmetropes participated in this study. High contrast square-wave
grating(s) with spatial frequency 17 c/d were used as the target in both experiments. In
the DOF objective measurement, the subject’s right eye looked at the target through a
Badal stimulator. The vergence of the target (i.e. accommodative stimulus, AS) changed
from 0.9 D to 2.1 D with 0.1 D step. The subject’s accommodative responses (ARs)
were recorded by a Canon R-1 optometer. The ARs at each AS level were compared
with the ARs to the AS of 1.5 D. The objective DOF was determined as the difference
between the AS, at which level the ARs were significantly different from the ARs at
1.5 D AS level, and the 1.5 D. The subjective DOF was measured using a two-channel
Badal system. The subject’s right eye looked through the system to view two identical
targets. One target was positioned at 1.5 D and the other was moveable. Each target
occupied one- half of the visual field. The subject was instructed to fixate at the
fixed target and move the moveable target until a just noticed blur was detected.
The difference between the positions of the two targets in diopters was defined as
the subjective DOF.
Results: The mean of the objective DOF determined in this study was ± 0.0913 ± 0.032
(S.D.) diopters. The mean of the subjective DOF was ± 0.525 ± 0.295 diopters. A paired
t-test showed that the difference is significant ( t [11] = 5.31, p < 0.0001).
Conclusions: The results of this study suggest that the sensory-motor threshold
to blurring of the retinal image is more sensitive when compared with the defocus
threshold of the visual perceptual system in the same subject.
CR: B. Jiang, None; H. Lin, None.
Support: NSU PFRDG #335441 and NSU HPD #335203
Purpose: Khosroyani and Hung have proposed a pre-programmed component within
the control system for accommodation responses to dynamic stimuli (Bulletin of
Mathematical Biology, 64, 2002). Manipulation of aberration dynamics during the
accommodation response has been shown to adversely affect focusing accuracy in
some subjects. Currently, the exact role of aberration dynamics in accommodation
control, and the temporal location of information gathering necessary to drive the
accommodation response is not known.
Methods: We used an adaptive optics (AO) system to manipulate the aberrations
in closed-loop of five subjects at various temporal locations in their response to a
plus or minus 0.75 D step. The AO system comprises two sensing channels, allowing
direct measurement of the ocular aberrations to occur independent of the deformable
mirror. The target was a Maltese cross at an accommodation level of 2 D illuminated
by monochromatic light (510 nm). Aberrations were corrected either: A) before the
step, B) after the step, C) before and after the step, D) during the accommodation
response latency period (after the stimulus change, but before an accommodation
response), or E) after the response latency period.
Results: The results were subject dependent. The most significant effect on
accommodation was a reduction in response gain. This effect was greatest when the
aberration correction was applied during the response latency period (condition D).
Conclusions: These data suggest that the accommodation system primarily utilises
information derived from the aberration dynamics during the response latency period
to guide closed-loop responses.
CR: K.M. Hampson, None; S.S. Chin, None; E.A.H. Mallen, None.
Support: EPSRC Grant EP/D036550/1
1790 - D655
Dynamics of Wavefront Aberrations of the Human Eye
1791 - D656
Repeatability and Agreement in the Accommodative Response Measurements
Y. Xiong, N. Wang. Dept. of Ophthalmology, Beijing TongRen Hospital, Capital
University of Medical Sciences, Beijing, China.
F. Barra1A, B. Antona1A, I. Sanchez1A, E. Gonzalez1A, A. Barrio1A, J.L. Cebrian1. AOptica II
(Optometria y Vision), 1Universidad Complutense de Madrid, Madrid, Spain.
Purpose: To investigate the dynamics of wavefront aberrations of the human eye
during accommodating.
Methods: An “E” card which can move from 5m to 0.1m was presented in front of
eyes. Different accommodation levels were evoked when the subjects watched the
movement of the card. Wavefront aberrations of 21 normal subjects (emmetropia,
vision acuity ≥20/20) were measured using Hartmann-shark aberrometer under
different accommodation levels (From 0D to 5D).
Results: Table 1 shows the Root Mean Square (RMS) of eye’s total wavefront aberrations
and high-order wavefront aberrations of different accommodation levels. The RMS
values of both aberrations decreased when the accommodation condition changed
from relaxation to tension. Table 2 shows the pupil size and the proportion of highorder wavefront aberrations under different accommodation levels. The proportion of
high-order aberrations was very stable under different accommodation levels, while
the pupil size decreased as the accommodation levels increased.
Table1: RMS values of eye’s total wavefront aberrations and high-order wavefront
aberrations under different accommodation levels:
Purpose: Clinical measurement of the accommodative response (AR) is an important
part of the optometric exam because inappropriate responses, over- or underaccommodation relative to the plane of the stimulus, are a frequent cause of asthenopia.
In order to demonstrate if a significant change in the AR has occurred, it is important
to determine the degree of repeatability intra-examiner of this measurement. The aim
of the present study was to compare the measurements of AR determined by using
four different clinical methods, including the Nott retinoscopy, MEM retinoscopy,
binocular cross cylinder (BCC) and autorrefractor at near. The hypothesis was that
the degree of repeatability of the four methods would be quite different and that the
four techniques could not be interchangeable.
Methods: The AR was measured on two separate occasions in 61 visually normal
subjects with a mean age of 19.7 years (range 18 to 32 years). In each method, all
measurements were recorded by the same examiner but different techniques were
applied by different examiners who were blind to the AR measurements obtained
by the other methods. The repeatability of the tests and the agreement between tests
was estimated by using the statistical method of Bland y Altman. We determined the
mean difference (MD), the standard deviation of the differences (SD) and the 95%
limits of agreement, i.e. the range over which 95% of values would be predicted to
lie (MD ± 1.96·SD). In all the methods it was computed the accommodative error, i.e.
the difference between the stimulus and the AR.
Results: The 95% limits of agreement for the accommodative error were: Nott: ±0.66
D; MEM: ±0.98 D; BCC: ±0.75 D and autorefractor: ±1.00 D. The Nott retinoscopy and
the BCC methods presented the best repeatability intraexaminer, with the smaller MD
(Nott: -0.10 D, BCC: -0.05 D) and the smaller 95% interval of agreement. Comparing
different techniques, the intervals between the 95% limits of agreement correspond to
substantial differences, always higher than ±0.75 D. The highest interval corresponds
to the comparison of MEM retinoscopy with BCC (±1.38 D).
Conclusions: From the point of view of its repeatability intra-examiner, the best
technique to evaluate the AR was the Nott retinoscopy. The degree of agreement
between the four techniques was poor.
CR: F. Barra, None; B. Antona, None; I. Sanchez, None; E. Gonzalez, None; A. Barrio,
None; J.L. Cebrian, None.
Support: None
Accommodation level
0D
1D
2D
3D
4D
5D
RMS of total aberrations
0.5068±0.2349um
0.4216±0.2218um
0.3919±0.2305um
0.3676±0.2198um
0.3574±0.1626um
0.2827±0.1278um
RMS of High-order aberrations
0.3336±0.1653um
0.2837±0.1487um
0.2611±0.1677um
0.2563±0.1775um
0.2486±0.1440um
0.1949±0.0989um
Table2 : Pupil size and proportion of high-order aberration under different
accommodation levels
Accommodation Level
0D
1D
2D
3D
4D
5D
Pupil Size
5.91mm
5.30mm
4.90mm
4.57mm
4.37mm
3.95mm
% of High-order Aberrations
65.82%
67.29%
66.73%
69.72%
69.56%
68.94%
Conclusions: The eye’s total wavefront aberrations decreased under a tensional
accommodation condition compared to that under a relaxable accommodation
condition. Although the pupil size also decreased when the accommodation level
increased, the proportion of high-order aberrations did not change significantly and
was kept at a high level.
CR: Y. Xiong, None; N. Wang, None.
Support: None
1788-1791
1792 - D657
Accommodation and Pupil Responses to Random-Dot Stereograms
1793 - D658
Working Distance During Near Work in Emmetropic Chinese Children
R. Suryakumar, R.S. Allison. Center for Vision Research, Computer Science and
Engineering, York University, Toronto, ON, Canada.
J. Bao1, H. Chen1, B. Drobe2, E. Seow2, F. Lu1. 1Sch of Optometry and Ophthal,
Wenzhou Medical College, Wenzhou, China; 2R & D Centre Singapore, Essilor Asia
Pacific PTE LTD, Singapore, Singapore.
Purpose: Recently, it has been shown that a transient pupil constriction occurs
following presentation of a random-dot stereogram with uncrossed disparity (Li, Z
and Sun, F. Exp Br Res, 2006, 168:436). We investigated the dynamic characteristics of
such pupil responses and whether they were coupled with changes in ocular focus.
Methods: Four subjects (mean age=26.8±3.6yrs) participated in the study. Stereo
half images were displayed on a pair of computer monitors placed at a distance of
60 cm in a Wheatstone stereoscope arrangement. Subjects fixated the center of the
random-dot stereogram which alternated between depicting a flat plane and a 0.5 cpd,
30 arc-minute peak disparity, sinusoidal corrugation in depth. In all cases, fixation
remained constant at the 60cm screen distance. Accommodation and pupil responses
were measured monocularly using a custom built, high-speed photorefractor at 100Hz
and analyzed offline. The onset and end of the accommodation and pupil responses
were identified to estimate amplitude. The pupil responses were then differentiated
to estimate peak velocity.
Results: A transient pupil constriction and positive accommodation were observed
during both uncrossed and crossed disparity presentations (Uncrossed: 0.26±0.12mm,
0.20±0.06D; Crossed: 0.41±0.40mm, 0.31±0.2D). The peak velocity of pupil responses
changed significantly as a function of amplitude (y=1.12x-0.38, R 2=0.34, p<0.05) and
initial pupil diameter (y=0.28x-2.41, R 2=0.64, p<0.05). Changes in pupil size were
associated with changes in accommodation. However, the ratio of pupil change
to accommodation was not significantly different between crossed and uncrossed
disparity (Uncrossed: 1.55±0.69mm/D; Crossed: 1.21±0.51mm/D; p>0.05).
Conclusions: While fixation was maintained at the plane of the screen, the finding
that pupil and accommodation changes have the same sign regardless of the sign of
disparity suggests the response was driven by the apparent depth in the stimulus
rather than its physical distance. The strength of the coupling between accommodation
and pupil responses appears to be similar for crossed and uncrossed disparity. The
amplitude and velocity of pupil responses depend on initial (starting) pupil diameter
confirming the non-linearity in the operating range of the pupil.
CR: R. Suryakumar, None; R.S. Allison, None.
Support: NSERC Canada, PREA, CIHR Strategic Training Grant
1794 - D659
Oculomotor Responses of Expert vs. Naïve Observers to Full and Impoverished
Stimuli
A.M. Horwood, P. Riddell. Psychology, University Reading, Reading, United
Kingdom.
Purpose: Previous studies of vergence and accommodation have shown that infants
and patient groups perform less well than adults. This could result from either a
developmental change or a naïve/expert effect since the adult studies often use
optometry students and staff as participants, potentially expert observers. This study
explicitly tested naïve vs. expert adult participants.
Methods: A remote haploscopic off-axis videorefractor measured simultaneous
accommodation and vergence (in dioptres and metre angles) to a detailed picture
stimulus at 4 positions between 0.3m and 2m. Blur, disparity and looming cues were
removed selectively by using a DOG patch, remote occlusion, and scaled targets
respectively. Participants were tested with all combinations of cues (8 conditions). 10
undergraduates naïve to vision experiments were matched by age, refractive error,
heterophoria, and fusion range with 10 orthoptics or optometry undergraduates
(“experts”) aware that accommodation and convergence were being studied.
Instruction set was identical and minimal.
Results: Mean stimulus/response slopes were higher in the expert group for vergence
(p=0.001). Except for the proximity-only target, mean accommodation slope was also
higher in the experts. Larger variance in the accommodation responses (particularly in
the “experts”) meant that the difference between groups did not reach significance in
this small sample. 73% of vergence responses and 67% of the accommodation response
slopes were steeper in the experts. While no participant over-converged by more than
10% for the target, many of the expert group over-accommodated.
Conclusions: We suggest that knowledge of the theory of vergence and accommodation
may enhance responses in comparison to the general population. Differences between
many reports of adult values and developmental and clinical literature may reflect
expert / naïve effects as well as developmental change.
CR: A.M. Horwood, None; P. Riddell, None.
Support: UK Dept of Health Grant PASI/PDA/01/05/031
Purpose: To investigate the working distance of emmetropic Chinese children during
near vision tasks, and to delineate some of the factors affecting working distance.
Methods: 91 emmetropic children (age 6 to 12 yrs) were divided into three groups:
group 1 (grades 1 and 2), group 2 (grades 3 and 4) and group 3 (grades 5 and 6).
Accommodative responses were measured for the right eye of each subject using a
Grand Seiko WV500 with the visual target (Maltese cross) 33 cm from the right eye,
and near phoria was measured using the modified Thorington test. Working distances
for three near tasks (writing, reading, and electronic game (Game-Boy) playing) were
measured with the Polhemus Fastrak system.
Results: Children placed their reading and writing material on a desk surface but
held the electronic game. Mean working distances were 20.57±5.65cm when writing,
24.28±6.32cm when reading, and 19.31±5.21cm when playing game. Working distance
increased with school grade for all three tasks. Children in group 3 showed longer
working distances than the others when writing and playing game (writing: p=0.001
for group 1 vs 3, p=0.051 for group 2 vs 3; game playing: p=0.003 for group 1 vs 3,
p=0.001 for group 2 vs 3). Distance variability during hand-held game playing was
less than for the other tasks (p=0.001), and the Harmon distance was correlated with
game-playing distance (r = 0.28, p=0.008). Although accommodative lags were large
and varied greatly between subjects (0.98D ± 0.67D), lag did not correlate with near
phoria or working distance.
Conclusions: Chinese emmetropic children work at very close distances, especially
when writing and electronic game-playing. The visual distance was shortest and most
stable when game-playing. Harmon distance played an important role when children
work with hand held material. But accommodative lag and near phoria did not affect
the working distance of emmetropic children. The relationship of working distance to
reading proficiency and the induction of myopia have yet to be determined.
CR: J. Bao, None; H. Chen, None; B. Drobe, None; E. Seow, None; F. Lu, None.
Support: R & D Centre Singapore, Essilor Asia Pacific PTE LTD
1795 - D660
A New Device for Clinical Testing of Distance Corrected Reading Acuity Under
Fully Standardized Conditions: The Salzburg Reading Desk-Advanced (SRDadv) - Proof of Concept
A.K. Dexl, H. Schlögel, M. Wolfbauer, G. Grabner. University Eye Clinic, Paracelsus
Medical University, Salzburg, Austria.
Purpose: To develop a new device for testing distance corrected reading acuity under
standardized circumstances.
Methods: The determination of reading performance is still the most relevant clinical
examination, whenever the potential benefits of surgical procedures for the correction
of presbyopia are assessed. A comparison of the results of different centres cannot
be easily performed without adequate test methods and meticulous standardization.
Based on the “Radner-Reading-Charts”, the SRD-adv was developed for testing reading
acuity under different luminance levels (5-100 cd/m 2) and -in addition- different
contrast levels by the implementation of a high-resolution computer-display (0,16 mm
pixel-interspace) in the original SRD prototype. One has to be aware that all at present
commercially available reading charts are using high contrast levels (approximately
85-95%). The added feature of testing with different, especially reduced contrast levels
(as an example a “standard” newspaper has only about 40-60% of contrast) will allow
to discriminate even smaller differences regarding every day reading abilities. As
measuring reading acuity with fixed distance does also not allow to draw conclusions
on the “every day reading ability” of patients, the continuously changing reading distance is
monitored by stereo-photometry, and is mathematically taken into consideration. The
reading angle (= inclination of the display), as an additional variable parameter, can
be chosen freely by the patient, to offer the most convenient test circumstances.
Results: Testing for validity and reliability has been performed with 924 single
measurements in distances between 15 and 63 cm, and reading angles between 60° and
90°. Based on the Radner Reading Charts an error range between logRad ± 0,0034 at 63
cm and logRad ± 0,0143 at 15 cm has been found (this is of no clinical relevance).
Conclusions: With the SRD-adv it is possible to obtain objective, valid and comparable
results as far as the true “reading abilities” of patients are concerned. This encompasses
reading acuity, reading speed and critical print size, under different contrast and
luminance levels, and subjectively convenient reading distance. Studies testing reading
acuity following a variety of surgical methods are currently under way in different
European centres with the use of the SRD-adv in order to confirm the potential of
this highly refined method for reading acuity evaluation.
CR: A.K. Dexl, Patent assignee, P; H. Schlögel, Patent assignee, P; M. Wolfbauer,
Patent assignee, P; G. Grabner, Patent assignee, P.
Support: Fuchs-Foundation for supporting Ophthalmology, Salzburg, Austria and
Adele-Rabensteiner-Foundation of the Austrian Ophthalmologic Society, Vienna,
Austria
1792-1795
1796 - D661
Simulated Eye Model Experiments for Selecting a Depth-of-Focus Metric
1797 - D662
Depth of Focus of Accommodating Intra-Ocular Lenses: A Paraxial Analysis
M. Bird1, J. Tabernero2, P. Artal2, H.A. Weeber1, P.A. Piers1. 1Research, Advanced
Medical Optics, Groningen, The Netherlands; 2Laboratorio de Optica, Universidad
de Murcia, Murcia, Spain.
A. Ho1,2, F. Manns3,4, J. Ale5,2, Y. Lee 6, J.-M. Parel4,5. 1Institute for Eye Research, Sydney,
Australia; 2School of Optometry & Vision Science, University of New South
Wales, Sydney, Australia; 3Department of Biomedical Engineering, University of
Miami School of Engineering, Coral Gables, FL; 4Ophthalmic Biophysics Center,
University of Miami School of Medicine, Miami, FL; 5Vision Cooperative Research
Centre, Sydney, Australia; 6Bascom Palmer Eye Institute, Miami, FL.
Purpose: An intraocular lens (IOL) that extends depth of focus (DOF) will result
in greater spectacle independence because of gains in pseudo-accommodation. To
determine DOF, a standard metric is needed to gauge the accuracy between subjective
and objective DOF measurements. This study reports on four different DOF metrics:
two through-focus modulation transfer function (MTF) responses at 6c/deg and
at 15c/deg; through-focus Strehl ratios (SR), and one that considers through-focus
ensquared energy (EE) on the image plane.
Methods: Corneal topography measurements of 24 real eyes were integrated into the
ZEMAXTM optical design program to create individual eye models (Tabernero et al.).
Two types of IOL were added: a lens designed to correct corneal spherical aberration
and a lens with positive spherical aberration. All eye models were astigmatism
corrected for a 4 mm entrance pupil in the spectacle plane with a standard Zernike
phase plate. In the same Zernike phase plate, -2D to +2D of defocus, in steps of 0.25D,
were added to step through the eye’s range of focus. At each step a white-light radial
MTF response was calculated at the image plane. At the same time, the SR and EE
(40μm by 40μm) on the image plane were recorded at each step. Through-focus plots
were generated from the radial MTFs for spatial frequencies of 6c/deg and 15c/deg.
The results from all eye models were averaged, and the full width at half maximum
for each of the through-focus plots was determined.
Results: The metrics provided varying DOF for the same lens type. The EE metric
provided the largest DOF (±2D), followed by the MTF-based metrics (≤±1.5D), and
finally the SR metric (±0.875D). Comparing the results from these simulations to those
of Piers et al., which showed DOFs of ±1D and lower, the 15c/deg MTF metric produces
the DOF that is most consistent with subjective measurements.
Conclusions: Based on these simulations, the 15c/deg metric appears to be the most
suitable for predicting DOF. More subjective data will allow a deeper analysis into
which metric best represents individual DOF.
CR: M. Bird, AMO, E; J. Tabernero, AMO, C; P. Artal, AMO, C; H.A. Weeber, AMO,
E; P.A. Piers, AMO, E.
Support: None
Purpose: To investigate the performance of one-lens (1LAIOL) and two-lens (2LAIOL)
accommodating intraocular lenses in terms of depth of focus (DoF).
Methods: A paraxial eye model, modified from the Navarro eye and adjusted for paraxial
focus, was used. To simulate the effect of AIOL implantation, the surfaces representing
the crystalline lens were replaced with one or two thin lenses. For reference, DoF of
the ‘natural’ eye (with the original crystalline lens surfaces) was calculated. A 20 μm
blur circle size limit was assumed throughout; giving a total DoF for the natural eye of
0.53D (4 mm pupil).
We studied the effect of AIOL position on DoF by varying the distance focus position
of the AIOL from 1 mm to 3 mm behind the iris. We also studied the effect of 2LAIOL
front/back lens power combinations on DoF by varying front lens power from 25D to
40D in 5D steps. In all cases, lens power (1LAIOL) or back lens power (2LAIOL) was
selected to maintain distance focus.
For each scenario, we studied the effect of near focus (up to 1 mm translation) on DoF.
We analysed two 2LAIOL cases; front lens translating forward, and back lens translating
backwards.Total DoF was defined as the limits of vergence in object space that produce
the 20 μm blur circle size.
Results: At distance focus, all AIOL had greater DoF (range=0.514D to 0.535D) than the
reference eye. Moving the position of all AIOL posteriorly (with a higher lens power to
maintain focus) increases DoF by 8.5mD (milli-dioptres) per mm of position change.
DoF of all AIOL decreases when focused for near; 1LAIOL fared worst (DoF decreasing
2.2mD per D of near focus), while DoF of 2LAIOL decreases from between 1.7 to 0.4mD
per D of near focus.
For 2LAIOL, DoF increases by 0.04mD per D of front lens power increase. Back lens
translating 2LAIOL show virtually no change in DoF with change in lens power; and
suffers the least DoF decrease with near focus. At distance focus setting, DoF of 2LAIOL
is independent of lens power.
We emphasise that all effects on DoF are minute, changing by less than 0.01D in all cases.
This is far smaller than the precision of any measurements of DoF.
Conclusions: Within practical limits, lens power and position of implantation of AIOL
have negligible effect on DoF.
CR: A. Ho, None; F. Manns, None; J. Ale, None; Y. Lee, None; J. Parel, None.
Support: NIH Grant 2R01EY14225; Australian Government CRC Scheme via Vision CRC,
Sydney, Australia; Henri and Flore Lesieur Foundation
1798 - D663
Omni-Focal Refractive Correction Lens -A Potential Substitute for Bi/MultiFocal Lenses
1799 - D664
A Novel Myopia Correcting Lens Which Reduces the Need for Accommodation
for Near Vision Tasks
S. Ben Yaish1, A. Zlotnik1, O. Yehezkel2, M. Belkin2, Z. Zalevsky3. 1Xceed Imaging Ltd.,
Petach tiqva, Israel; 2Medicine, Goldshleger Eye Research Institute Shiba hospital,
Ramat Gan, Israel; 3School of Engineering Bar-Ilan University, Ramat-Gan, Israel.
O. Yehezkel1, S. Ben Yaish2, A. Zlotnik 2, M. Belkin1, Z. Zalevsky3. 1Faculty of Medicine,
Tel-Aviv University, Tel Hashomer, Israel; 2Xceed Imaging, Petach Tikva, Israel;
3
School of Engineering, Bar-Ilan University, 52900 Ramat-Gan, Israel.
Purpose: To test a novel Extended Depth Of Focus (EDOF) lens, potentially
capability of correcting: Myopia, hyperopia with regular/ irregular astigmatism
and presbyopia.
Current methods of correcting these refractive errors are not optimal, not allowing
simultaneous vision for far and near or correcting irregular astigmatism in spectacles
and soft contact lenses.
EDOF technology extends the depth of focus for a given lens or imaging system,
without appreciable loss of energy. It is produced and incorporated as a coating or
engraving on the surface any kind of- spectacles or contact lens
Methods: After optical bench testing for verification of simulation results, the
technology was evaluated on small subject groups with spectacles and contact lenses
on which the EDOF elements were incorporated. Five astigmatic (up to 2.00 D) and 10
presbyopic subjects (requiring 1.75-2D addition for near vision) were examined. The
enhancing optical element was added to each of the subject’s distance correction.
Results: The optical bench results showed correction of 2.00 D of astigmatism
(including irregular astigmatism) and improvement of 2.5 D for the near distance.
The evaluation over the trial group showed correction of 2.00 D for astigmatism and
in presbyopic subjects the visual acuity for far and near distances was 6/6 and J1
respectively. The subjects’ stereo perception, color vision and contrast sensitivity
were not affected.
Conclusions: The EDOF system seems to provide a satisfactory single-lens solution for
myopes and hyperopes with deficient accommodation ability and/or with irregular
and regular astigmatism. Contact lens performance is apparently better than those
of existing multi and bi-focal lenses.
CR: S. Ben Yaish, xceed imaging ltd., F; A. Zlotnik, xceed imaging ltd., F; O. Yehezkel,
xceed imaging ltd., F; M. Belkin, None; Z. Zalevsky, xceed imaging ltd., F.
Support: None
Purpose: Accommodative effort during childhood is associated with the progression
of myopia. We developed a new type of lens that, unlike traditional optical lenses
is neither refractive nor diffractive. This lens is based on Extended Depth Of Focus
(EDOF) technology that spreads the depth of focus for a given lens or imaging system,
with minimal loss of energy. Thus this lens potentially enables the visual system to
focus on near and distance objects simultaneously without need for accommodation.
Therefore, the use of the new lens in corrective optics at the appropriate ages may
reduce the need for accommodation and possibly diminish myopization.
Methods: The functionality of the lens as depth of focus extender was checked
first in simulation with human eye model on an optical design software and the
simulation results were verified on an optical bench. Tests on small trial group were
then conducted on 5 myopic subjects with BCVA of 6/6 for the far distance (ETDRS)
and with age range of 24-35 years. In order to test our lens we reduced 1.00 D from
their optical correction and added the EDOF. We also measured contrast sensitivity,
color vision and stereo tests while wearing the EDOF lens. In order to verify the EDOF
lens ability to reduce or prevent the need for accommodation for near, 10 presbyopic
subjects with addition requirements of 1.75-2.00D were used.
Results: The results on the optical bench showed extension of depth of focus equivalent
to 2.50 D. The experiments on trial group showed that the EDOF lens corrected 1.00 D
of myopia. The presbyopic subjects’ testing showed that the EDOF lens corrected their
far and near vision to 6/6 and J1 respectively (i.e. improvement of 2.00 D). Stereoscopic
and color vision as well as contrast sensitivity were not affected.
Conclusions: The EDOF lens is capable of correcting up to 1.00 D of myopia. This
ability to correct low myopia coupled with its effect in reducing the necessity for
accommodation for near vision suggests that it may be tested for the mitigation of
accommodation-induced component of myopia.
CR: O. Yehezkel, Xceed imaging, P; S. Ben Yaish, Xceed Imaging, F; A. Zlotnik,
Xceed Imaging, F; M. Belkin, None; Z. Zalevsky, xceed imaging, F.
Support: None
1796-1799
1800 - D665
Testing Reading Performance With the Salzburg Reading Desk (SRD) After
Implantation of the AcuFocusTM 7000 Corneal Inlay (ACI) in Presbyopic Patients
O. Seyeddain, M. Hohensinn, G. Grabner, A.K. Dexl. University Eye Clinic, Paracelsus
Medical University, Salzburg, Austria.
Purpose: The determination of Reading Performance (RP) is still the most important
clinical examination, whenever the potential benefits of surgical procedures for the
correction of presbyopia are compared. The bilateral RP with a new, standardized
device (SRD) in 15 patients before, and within 1 year after implantation of the ACI in the
non dominant eye of presbyopic patients, has been investigated. This is a 10 micron
thin, intracorneal implant with a central aperture of 1.6 mm and an outside diameter
of 3.8 mm, with nutritional micropores, designed to improve RA.
Methods: Based on the “Radner-Reading-Charts”, the SRD was developed for testing
reading acuity (RA) under standardized illumination. As measuring RA with fixed
distance does not allow to draw conclusions on the “every day reading ability”
of patients, the continuously changing reading distance (RD) is monitored by stereophotometry, and is mathematically taken into consideration. The reading angle, as an
additional variable parameter, can be chosen freely by the patient, to offer the most
convenient test circumstances. Bilateral RP was examined before and within 1 year
after implantation of the ACI.
Results: All implanted eyes showed an increase of RA and had a significant
decrease in RD after ACI implantation. The SRD demonstrates that patients achieve
an improvement in their everyday RP by “gaining distance”. Average RD (cm)
improvement after 1 year measured with the SRD: mean 11.9 ± 8.65 (p< 0.0002). The
average reading improvement after 1 year obtained with the SRD was a mean 2.2 ±
1.52 lines. Increasing depth of focus after implanting the ACI therefore improves RA
by reducing the patients own RD.
Conclusions: The SRD provides objective, valid and comparable results as far as the
true “reading abilities” of trial subjects are concerned. It can be demonstrated that
the ACI significantly improves RA in presbyopic patients.
A newly developed “SRD-advanced” (with a high-resolution monitor, which offers
the additional possibility to test with different contrast levels), will in the near future
allow to obtain even more detailed information on the “every day reading ability” of
patients after any type of presbyopic surgery. Studies testing RA following a variety
of surgical methods e.g. the implantation of multifocal IOL´s are currently under way
in different European centers with the use of the SRD in order to confirm the potential
of this highly refined method for RA evaluation.
CR: O. Seyeddain, None; M. Hohensinn, None; G. Grabner, patent holder, P; A.K.
Dexl, patent holder, P.
Support: None
1800
253. Optical Imaging and Image Processing Organizing Section: VI
1831 - D740
Registration of Cirrus HD-OCT Images With Fundus Photographs, Fluorescein
Angiographs and Fundus Autofluorescence Images
1832 - D741
Automated Segmentation of the Retinal Vasculature in 3D Optical Coherence
Tomography Images
H. Narasimha-Iyer1, B. Lujan2, J. Oakley1, S. Meyer1, S.S. Dastmalchi1. 1Carl Zeiss
Meditec, Dublin, CA; 2Bascom Palmer Eye Institute, University of Miami Miller
School of Medicine, Miami, FL.
M. Niemeijer1, M. Sonka1, M.K. Garvin1, B. van Ginneken1,2, M.D. Abramoff 1.
1
Ophthalmology / Electrical Engineering, The University of Iowa, Iowa City, IA;
2
Image Sciences Institute, Utrecht University, Utrecht, The Netherlands.
Purpose: Spectral Domain Optical Coherence Tomography is a high-speed, highresolution, non invasive method that allows visualization of structures in the eye.
Application of SD-OCT technology in routine clinical practice is relatively new and
its clinical interpretation along with other traditional imaging methods is being
studied. Hence it is of high value to correlate the OCT image with modalities such as
Fundus Photography, Fluorescein Angiography (FA), and Fundus Autofluorescence
imaging (FAF). Automated registration algorithms have been developed to register
the reconstructed OCT fundus image to these other modalities.
Methods: Existing algorithms were used to segment the Internal Limiting Membrane
(ILM) and Retinal Pigment Epithelium (RPE) layers from the Cirrus HD-OCT data
set. These segmentations were then used to obtain an en face view of the OCT volume
which enhances the contrast of the blood vessels compared to the background. The
blood vessels were segmented from the en face OCT image and the fundus image
and an algorithm based on aligning the blood vessel segmentations was used to
register the images.
Results: The registration transforms the OCT fundus image and the other imaging
modalities into the same co-ordinate frame. This allows correlating lesions amongst
these different modalities, and allows for the cross-sectional analysis of pathological
features visualized on traditional planar imaging. Registration of images provides
additional diagnostic information over what can be achieved from each imaging
modality independently. For example, the overlay of derived OCT thickness maps on
the fundus images gives valuable clinical information for diagnosis, assessment of
disease progression, quantitative monitoring of treatment effect, or surgical planning
for focal laser treatment.
Conclusions: The described method helps to automatically register en face images
from OCT data cubes to images obtained from other ophthalmic imaging modalities
such as color fundus, FA and FAF. This capability can form a valuable additional
diagnostic resource for the clinician and researcher by enabling accurate quantitative
and qualitative comparisons between OCT and other imaging modalities.
CR: H. Narasimha-Iyer, Carl Zeiss Meditec Inc, Dublin CA, E; B. Lujan, Carl Zeiss
Meditec Inc, Dublin CA, F; J. Oakley, Carl Zeiss Meditec Inc, Dublin CA, C; S. Meyer,
Carl Zeiss Meditec Inc, Dublin CA, E; S.S. Dastmalchi, Carl Zeiss Meditec Inc, Dublin
CA, E.
Support: None
Purpose: To evaluate an automated computer algorithm for segmentation of the retinal
vasculature in 3D spectral OCT. Segmentation of vessels will allow inter-subject
registration of multiple 3D-OCT volumes over time, registration of OCT with fundus
photographs and angiograms.
Methods: 28 3D-OCT volumes were obtained (Carl Zeiss Meditec Cirrus 3D-OCT,
200x200x1024 voxels) from 28 normal subjects (28 eyes), 14 were centered on the optic
nerve head (ON) and 14 were centered on the fovea. An automated layer segmentation
algorithm [1] was applied to each volume to identify individual retinal layers. The vessel
silhouettes were used to identify the vessel positions. Using the layer segmentation, the
outer retinal layer which showed the highest vessel silhouette contrast was averaged
in the z direction. A 2D projection image of the vessel silhouettes was obtained for all
3D OCT volumes. To develop a method for vessel segmentation based on the projection
images, the set of 28 images was split into a training set of 12 images (6 ON, 6 maculacentered) and a test set of 16 images (8+8). For each of the training images, all vessel
pixels were indicated by an expert. Next, two separate kNN classifiers were trained
for the ON-centered and the macula-centered projections. A Gaussian derivatives
filterbank (2nd order, σ=1,2,4,8) was applied to each of the 2D projection images to
extract pixel features. All pixels from the training images were used in the training
procedure. The two trained classifiers were applied to their respective test sets. A
human observer indicated for 100 randomly selected pixels in each of the test images
(1600 pixels in total) whether the pixel belonged to a vessel or not.
Results: Comparison of the automated segmentation with the observer-generated
independent standard indicated an area under the ROC curve (Az) of 0.96 for both
the ON and macula-centered volumes combined. For the ON-centered test images,
the Az was 0.97 and for the macula-centered images the Az was 0.94. As the results
indicate, smaller vessels in the macula-centered images were more difficult to segment
than the larger vessels near the ON.
Conclusions: A novel automated algorithm can segment the retinal vasculature in
3D-OCT images with a performance close to that of a human expert.
[1] M. Haeker, M. Sonka, R. Kardon, V.A. Shah, X. Wu, and M.D. Abramoff, “Automated
segmentation of intraretinal layers from macular optical coherence tomography
images”, Medical Imaging, 6512, SPIE, 2007
CR: M. Niemeijer, The University of Iowa, P; M. Sonka, The University of Iowa, P;
M.K. Garvin, The University of Iowa, P; B. van Ginneken, None; M.D. Abramoff,
The University of Iowa, P.
Support: Supported, in part, by R01-EB004640
1833 - D742
Comparing the Performance of Retinal Image Registration Algorithms Using
the Centerline Error Measurement Metric
1834 - D743
Tracking the Retina - A Comparative Study
S. Lee1A, J.M. Reinhardt1A, M. Niemeijer1B, M.D. Abramoff 1C,2. ABiomedical Engineering,
B
Ophthalmology and Visual Sciences, COphthalmology & Visual Sciences,
Electrical and Computer Engineering, 1The University of Iowa, Iowa City, IA;
2
Veterans’ Administration Medical Center, Iowa City, IA.
Purpose: to compare three frequently used coordinate transformation models for
retinal image registration; affine, quadratic and radial distortion correction (RADIC)
model. We compare the registration accuracy using a quantitative metric of vessel
centerline error measurement (CEM), visually inspect the result, and finally suggest
a transformation model that is optimal for retinal color images.
Methods: 500 color fundus image pairs (1,000 images, 500 eyes) were randomly
selected from a diabetic retinopathy screening program in the Netherlands. The rigid
coordinate distortion in retinal image is described by the affine model. The quadratic
model describes the spherical-to-planar projective distortion in retinal imaging. The
RADIC model that we recently published is a combination of affine model following
the radial distortion correction. The CEM is evaluated from the overlapping region,
and the registered montage image is visually inspected to assess the geometric
alignment in the non-overlapping region.
Results: The test data are registered in a pair-wise manner to successfully generate
462 montage images and 38 pairs were not registered due to poor image quality or
insufficient correspondence. Because of the nonlinear property, 145 pairs registered by
the quadratic model show significant warping in the non-overlapping region. For the
successfully registered pairs, the CEMs were 1.83±0.05 (affine), 1.61±0.07 (quadratic),
and 1.72±0.04 (RADIC) pixels. Visual inspection indicated that even though the
quadratic model has the lowest CEM, the RADIC model shows the least distortion
in registering retinal images.
Conclusions: From these results, the RADIC model is found to have small error and the
least distortion in retinal images registration. We are currently pursuing more objective
techniques to compare the performance of retinal image registration algorithms.
CR: S. Lee, Patent application, P; J.M. Reinhardt, Patent application, P; M. Niemeijer,
None; M.D. Abramoff, Patent application, P.
Support: Supported by National Eye Institute Grant EY017066, Department of Defense
Grant A064-032-0056, Research to Prevent Blindness, and the Wellmark Foundation
M. Broehan1, C. Amstutz2, J. Kowal1. 1MEM Research Center, University of Bern,
Bern, Switzerland; 2Department of Ophthalmology, University Hospital Zuerich,
Zuerich, Switzerland.
Purpose: Accurate placement of lesions is crucial for the effectiveness and safety
of a laser photocoagulation treatment. Computer assistance has the capability for
improvements with respect to accuracy and patient safety. To account for patients’
eye movements during treatment execution a successful computer assisted system has
to reliably track the retina. The aim of the presented study is to investigate different
published algorithms concerning their ability to solve the real-time registration
problem during computer assisted laser photocoagulation and to evaluate different
retina imaging modalities regarding their potential to be used for intra-operative
image acquisition.
Methods: Within the study image and video data from both eyes of 35 patients
were recorded. Central fundus images were acquired using a non-mydriatic fundus
camera VISUCAM NM/FA (Carl Zeiss Meditec, Jena, Germany). Video data streams
were captured with a laser slit lamp LSL 532s with laser VISULAS 532s (Carl Zeiss
Meditec, Jena, Germany) equipped with a DigiCam beam splitter adapter and a
scanning digital ophthalmoscope SDO-A (WILD Medtec, Wien, Austria). The fundus
images served as planning modality against which the intra-operatively acquired
video streams were registered. To investigate retina tracking methods the concept
was to initially co-register the planning modality and the first retina video frame
using a feature-based registration algorithm that iteratively traces the vasculature.
The obtained transformation parameters were then updated by tracking the frameto-frame motion. After reviewing several approaches for real-time co-registration
two strategies were selected: an intensity-based template matching using different
similarity metrics and a method based on the construction of a two-dimensional
retinal vessel template.
Results: Applied to the acquired patient data the presented algorithms revealed high
potential for solving the real-time registration task, whereas the feature-based method
seemed to be more accurate and robust. The ratio between successful frame-to-frame
registrations and tracking-loss events was significantly higher for SDO video streams
compared to slit lamp video streams. Additionally, the employment of red-free filters
improved the tracking reliability considerably for both devices.
Conclusions: The feature-based method would most probably be the preferred
tracking strategy. As an intra-operative imaging device the SDO appeared to be
more appropriate compared to the slit lamp due to the larger field of view and better
achievable image quality.
CR: M. Broehan, None; C. Amstutz, None; J. Kowal, None.
Support: Carl Zeiss Meditec AG, Jena, Germany
1831-1834
1835 - D744
Three-Dimensional Mapping of the Fovea in Normal and Diseased Retina
A.M. Dubis, J.T. McAllister, J. Rha, J. Kuchenbecker, J. Carroll. Ophthalmology, Medical
College of Wisconsin, Wauwatosa, WI.
Purpose:The fovea centralis is a characteristic feature of nearly all primate retinae.
Here we sought to compare foveal topography (pit depth, slope, & diameter) with
other measures such as cone packing density and axial length.
Methods:Fourteen myopes and 11 emmetropes were imaged using a Zeiss Stratus
OCT. In addition, we retrospectively examined foveal OCT scans of 3 BCM carriers
(for whom images of the cone mosaics had been previously acquired using an adaptive
optics ophthalmoscope). An IOL master was used to obtain axial length measurements
in all subjects. All image processing was done using custom MatLab software, and
foveal reconstructions were fit to a 2D difference-of-gaussian function in order to
extract quantitative parameters describing individual fovea.
Results:We found little intra-subject variation in the shape of the fovea. Even with the
most variable parameter (pit depth), there was high correlation between any given
subjects’ 2 eyes, indicating near-perfect symmetry (p < 0.0001, paired T-test). All other
metrics (pit diameter, axial length, radius of curvature, and slope) showed similar
correlation. We tested one prediction of a current model of foveal development: retinal
stretch during development should result in more shallow foveal pits. Interestingly,
we found that in myopes, but not emmetropes, individuals with longer axial lengths
had more shallow foveal pits (p = 0.045). Previously, using adaptive optics imaging
it was shown that BCM carriers have fewer numbers of cones. For the BCM carriers,
we found that they had more shallow foveal pits (in addition to dramatically reduced
cone density).
Conclusions:We have developed a new analytical technique to increase the utility
of time domain OCT in both clinical and research settings. This can be used on
existing OCT data sets, and in the future could easily be integrated to provide a real
time analysis (currently done off-line). We observed significant variation in foveal
topography across subjects. It is known that the peak cone density in individuals with
normal vision can vary by a factor of 3, so future work will combine adaptive optics
imaging and this new OCT technique to examine the relationship between the cone
mosaic and the fovea. Preliminary data from the BCM carriers (with dramatic reduction
in cone density) suggests that the relationship in normals may not be profound. Our
data supports the hypothesis that foveal pit development is correlated to retinal
stretch, however the relationship only held in myopes. The absence of this correlation
in emmetropes suggests that other mechanisms must modulate pit depth.
CR: A.M. Dubis, None; J.T. McAllister, None; J. Rha, None; J. Kuchenbecker,
None; J. Carroll, None.
Support: The Gene & Ruth Posner Foundation, RD & Linda Peters Foundation, Fight
for Sight, Research to Prevent Blindness
1836 - D745
A Raytraced Three Dimensional Display System for Visualizing Subtle
Structures of the Vitreo-Retinal Interface Using Data From the Cirrus-HD OCT
C.G. Glittenberg1,2, C. Falkner1,2, F. Zeiler1,2, S. Hagen1,2, H. Paulina1,2, I. Krebs1,2, S.
Binder1,2. 1Dept of Ophthalmology, Rudolph Foundation Clinic, Vienna, Austria;
2
Ludwig Boltzmann Institute for Retinology and Biomicroscopic Laser Surgery,
Vienna, Austria.
Purpose: To create a 3D display system for the Carl Zeiss Meditec Cirrus HD-OCT which can
improve the visualization of subtle structures in and around the vitreo-retinal interface.
Methods: Spectral domain examinations were performed on patients with epiretinal
membranes (17 eyes), macular holes (11 eyes), and posterior vitreal detachments (16 eyes) using
the Cirrus HD-OCT. Several subroutines were programmed in the raytracing and rendering
program Cinema 4D XL Studio Bundle R10.5 (Maxon Computer Inc.) which visualize the
previously acquired data using raytracing algorithms. These raytracing algorithms allow
the subroutines to calculate and visualize shadows being cast and or received by every
structure in the specimen. It was hoped that these shadows would increase the clarity and
sharpness of very subtle structures of the vitreo-retinal interface, such as epiretinal traction
lines and traction lines in and around the posterior hyaloid. The data was reviewed using the
Carl Zeiss Meditec Cirrus HD OCT 2.0 advanced visualization system (the area around the
vitreoretinal interface was studied using a 100 micron thick ILM fitted slab). Afterwards, the
same specimen was visualized with the 3D visualisation system created for this project.
Results: Because of the use of raytraced shading, epiretinal traction as well as traction within
the vitreous itself could be visualized more distinctly using the 3D rendering software
than with the ILM fitted slab, allowing a better understanding of 3D configuration of forces
affecting the retina.
Conclusion: The improved visualization of the subtle structures in and around the retinal
surface may help us gain a better understanding of the pathological mechanisms which are
involved in the genesis of these diseases. Further research is necessary to ascertain if enough
additional information can be gathered using this display system to affect our therapeutic
decision making process.
CR: C.G. Glittenberg, Early Advanced Program (EAP) for Cirrus HD-OCT (Carl Zeiss
Meditec), F; Consultant Work for Carl Zeiss Meditec, C; Consultant Work for Carl Zeiss
Meditec, R; C. Falkner, EAP, F; F. Zeiler, EAP, F; S. Hagen, None; H. Paulina, None; I. Krebs,
EAP, F; S. Binder, EAP, F.
1837 - D746
Errors in Three-Dimensional Imaging of Retinal Pigment Epithelium Surface
by Using Spectral-Domain Optical Coherence Tomography
1838 - D747
Image Quality Enhancement in Ophthalmic Optical Coherence Tomography by
Frame Registration and Averaging
Y. Ojima1,2, M. Hangai1,2, A. Sakamoto1,2, D. Iwama1,2, A. Otani1,2, A. Tsujikawa1,2, N.
Yoshimura1,2. 1Ophthalmology, Kyoto University Graduate School of Medicine,
Kyoto, Japan; 2Kyoto OCT Reading Center, Kyoto, Japan.
P. Liu1,2, O. Tan1, Y. Li1, D. Huang1. 1Ophthalmology, Doheny Eye Institute, Los
Angeles, CA; 2College of Biomedical Engineering & Instrument Science, ZheJiang
University, HangZhou, China.
Purpose: To determine errors in automatic segmentation of the anterior borders of
the retinal pigment epithelium (RPE) in three-dimensional (3D) imaging of the RPE
surface in macular diseases.
Methods: We imaged 22 eyes with macular disease [10 with central serous
chorioretinopathy (CSC) and 12 with polypoidal choroidal vasculopathy (PCV)],
using spectral-domain optical coherence tomography (OCT) (3D-OCT1000, Topcon).
Raster scan protocol of 512 x 128 covering a 6 x 6 mm macular area was used. Automatic
segmentation of the anterior borders of the RPE line in 128 B-scan images, followed
by 3D topographic mapping of the resulting RPE plane, were performed using TMS
software, version 2.10.(Topcon Medical Systems, Inc) Errors per B-scan image were
graded and classified. The RPE surfaces depicted by the automatic and manual
segmentation of the anterior borders of the RPE were compared in terms of subRPE lesions by color fundus photography and fluorescein or indocyanine green
angiograms.
Results: Sub-RPE lesions such as pigment epithelial detachment, polypoidal lesions,
and branching vascular network were seen as varying levels of RPE surface elevation
against the flat RPE surface. Errors in automatic segmentation of the RPE were
classified into 3 groups. The first group included critical errors: lines were misplaced
on intraretinal high-reflectivity in case the reflectivity of RPE lines was decreased
due to the serous retinal detachment. or beneath highly reflective lesions such as hard
exudates and fibrin. The second group included mild errors: small focal elevation of
the RPE surface, representing bulges in CSC, was missed. The third group included
minor errors: lines were misplaced on neighboring highly reflective lines such as
photoreceptor inner and outer segment junction(IS /OS) and OS. First and second
errors interfered with the depiction of subretinal lesions in 3D RPE surface imaging. We
considered segmentation as successful when images did not include first and second
errors. The average success rates were 86.4% in CSC and 79.9% in PCV.
Conclusions: Sub-RPE lesions can be effectively depicted by 3D RPE surface imaging by
segmentation of its anterior borders. The segmentation algorithm should be improved
to prevent errors that critically interfere with the depiction of sub-RPE lesions.
CR: Y. Ojima, None; M. Hangai, None; A. Sakamoto, None; D. Iwama, None; A.
Otani, None; A. Tsujikawa, None; N. Yoshimura, None.
Support: a Grant-in-Aid for Scientific Research (18591917) from the Japan Society for
the Promotion of Science(JSPS)
Purpose: To evaluate quality enhancement for Fourier-domain optical coherence
tomography (FD-OCT) images by averaging multiple registered frames.
Methods: 7 normal subjects were scanned with a commercially available FD-OCT
system (RTVue with software version 2.7, Optovue, Fremont, CA) . The system scans
26,000 a-scans per second and has 5 micron axial resolution. Subjects were scanned
with line scans on retina (centered at fovea, scan length=6mm), cornea (centered at
vertex, scan length=6mm) and anterior chamber angle (scan length= 4mm). Sixteen
consecutive frames are acquired for each scan. A reference frame was picked by the
operator and a rectangular region was drawn on the reference frame. An automatic
algorithm was applied to register other frames to the content in the rectangle. The
algorithm automatically determines if registration is successful for each frame.
Successfully registered frames were averaged in the logarithmic domain. Contrastto-noise ratio (CNR) enhancement was used to quantify the reduction of background
and speckle noise. CNR enhancement ratio is equal to the CNR of averaged image
divided by CNR of reference image. To evaluate edge preservation, a cross correlation
parameter β (F. Sattar et al., “Image enhancement based on a nonlinear multiscale
method,” IEEE Trans. Image Processing, vol. 6, pp. 888-895, June 1997) was used. The
interpretation of β is: 0 to 0.20, poor; 0.21 to 0.40, fair; 0.41 to 0.60, moderate; 0.61 to
0.80, good; and above 0.80, excellent.
Results: The values of CNR enhancement ratio and β are shown in Table 1
Conclusions: The frame-averaging algorithm on the RTVue FD-OCT system
successfully improved image quality by suppressing background and speckle noises.
A moderate loss of edge sharpness was observed, indicating that there is room for
further improvement of the registration algorithm. The algorithm worked best on
corneal images.
Table 1. CNR enhancement ratio and β result
Scan location
CNR enhancement ratio
Retina
2.01 ± 0.67
Angle
3.64 ± 1.32
Cornea
5.57 ± 1.65
β
0.53 ± 0.09
0.44 ± 0.03
0.54 ± 0.19
CR: P. Liu, None; O. Tan, Optovue, Inc., F; Optovue, Inc., P; Y. Li, Optovue, Inc.,
F; Optovue, Inc., P; D. Huang, Optovue, Inc., F; Optovue, Inc., I; Optovue, Inc., C;
Optovue, Inc., P; Optovue, Inc., R.
Support: NIH grants R01 EY018184-01, NIH grants R01 EY013516, P30 EY03040;
Research to Prevent Blindness; Optovue, Inc;CHINA SCHOLARSHIP 2007U07002
1835-1838
1839 - D748
Pathology Insensitive Quality Assessment for Optical Coherence Tomography
P.C. Barnum1, M. Chen2, H. Ishikawa 3, G. Wollstein 3, J. Schuman3. 1Robotics Institute,
Carnegie Mellon University, Pittsburgh, PA; 2Intel Research, Pittsburgh, PA;
3
UPMC Eye Center, Eye and Ear Institute, Ophthalmology and Visual Science
Research Center, Department of Ophthalmology, University of Pittsburgh School
of Medicine, Pittsburgh, PA.
Purpose: The quality of optical coherence tomography (OCT) images has a significant impact
on measurements and diagnosis. The device provides an overall score for signal strength, but
when only part of the image is poor, global quality metrics might not suffice. The purpose of
this study was to develop an automated method for determining the quality of individual
A-scans, in a way that is insensitive to pathology.
Methods: Three OCT experts independently labeled the quality of each A-scan in 270 images.
There were 90 images each of the macula, optic nerve head, and circumpapillary retinal nerve
fiber layer. To test robustness to pathology, one-third of the eyes had no glaucoma, one-third
had early glaucoma, and one-third had advanced glaucoma. Using the experts’ labels, we
trained a hierarchy of support vector machines (SVM) at multiple scales and used histogrambased metrics. Specifically for the SVM, we projected different sized groups of A-scans into
a high dimensional space, then compute the hyperplane that minimizes classification error.
To improve the classification performance, the scans were normalized to be insensitive to
various effects, such as pathology and eye movement during acquisition.
Results: There was strong agreement between the experts and our new algorithm. The
following chart is the percent agreement between each of the three experts, their mode,
and our new algorithm
G.W.
H.I.
J.S.
Mode
Algorithm
G.W.
93
94
97
93
H.I.
93
92
95
95
J.S.
94
92
97
92
Mode
97
95
97
95
Algorithm
93
95
92
95
-
For our algorithm, the area under the receiver operating characteristic curve (AUC) was 0.94
for the macula, 0.96 for the optic nerve head, and 0.95 for the retinal nerve fiber layer.
Conclusions: We show that our automated algorithm performs on par with experts in
discriminating local OCT image quality. This localized assessment can be used to improve
the performance of segmentation and image fusion algorithms.
CR: P.C. Barnum, None; M. Chen, None; H. Ishikawa, None; G. Wollstein, Carl Zeiss
Meditec, Inc; Optoview, F; J. Schuman, Alcon; Allergan; Carl Zeiss Meditec, Inc.; Merck;
Optoview; Heidelberg Engineering, F; Carl Zeiss Meditec, Inc., P; Alcon; Allergan; Carl Zeiss
Meditec, Inc.; Merck;Heidelberg Engineering, R.
Support: NIH RO1-EY13178-08, P30-EY08098, EY13178, The Eye and Ear Foundation
(Pittsburgh, PA) Research to Prevent Blindness, Inc.; The first author performed this work
at Intel Research Pittsburgh CT: www.clinicaltrials.gov, NCT00286637
1841 - D750
A Fast, High Resolution System for Converting 35mm Ophthalmic Slides to
Digital Images
1840 - D749
Clinical Application of Matched Filter Processing of Digital Color Fundus
Images
T. Tatsumi. Chiba University Ophthalmology, Chiba, Japan.
Purpose: The digital color fundus image with Matched Filter processing reported by
Chaudhuri in 1989 is made up of 2.5x105 pixels, but the resolution of digital color fundus
images has improved to more than 1.0x107 pixels. The higher resolution suggested
that this technique might be used to study blood vessels and vascular diseases of the
retina. However, the possibility also existed that it could also enhance the appearance
of nerve fibers. The purpose of this study was to determine the usefulness of highresolution digital color fundus imaging with matched filter processing.
Method: A digital camera (D80, Nikon) was attached to a no mydriasis-type of
fundus camera (TRC-NW6S, Topcon) to take non-compressed photographs of the
fundus. The non-compressed color fundus photographs were saved and processed
by the Matched Filter program. Eyes with diabetes retinopathy, age-related macular
degeneration, branch retinal vein occlusion, and glaucoma were studied. We compared
the matched filter images with the fluorescein angiograms (FA) (TRC-50IX, Topcon),
optical coherence tomograms (OCT), and results of the Humphrey field analyzer
(HFA).
Results: Indistinct blood vessels were enhanced by the matched filter processing, and
leaked blood, such as hard exudates, was enhanced. However, the leakage and the
circulation changes were not sufficient to be used for diagnosis. Structures considered
to be reflections from nerve fibers were seen, and nerve fiber layer defects (NFLDs)
were enhanced in eyes with glaucoma. In addition, a retinal brightness peripapillary
profile of one disc diameter demonstrated that the brightness in the part corresponding
with the NFLD was reduced. This profile corresponded with the nerve fiber thickness
measured by OCT and was able to explain the results of HFA.
Conclusions: The Matched Filter processing of retinal vascular lesions is useful for
diagnosis only from a color fundus images, but does not substitute for FA. In addition,
The matched filter processing enhanced not only the blood vessels but also the nerve
fibers. This method is simple and easy and can be carried out with comparatively
inexpensive equipment in comparison with OCT, and we conclude that it will be
useful for the diagnosis of the glaucoma.
CR: T. Tatsumi, None.
Support: None
1842 - D751
Image Averaging in Fundus Autofluorescence Utilizing Fundus Photography
M.D. Ober1, J.E. Kim2, T. Trozak1, H. Demirci1. 1Department of Ophthalmology, Henry
Ford Health System, West Bloomfield, MI; 2Department of Ophthalmology, Medical
College of Wisconsin, Milwaukee, WI.
M.E. Verdugo1, P. Nadolny1, J. Buonomo1, A. Sasai1, B. Lay2, G. Dagniaux2.
1
Ophthalmology, Allergan, Inc., Irvine, CA; 2ADCIS SA., Herouville-Saint-Clair,
France.
Purpose: To develop a system for digitizing 35mm fundus slides to: 1) store images
efficiently, 2) improve the preservation of clinical study data and, 3) prepare data for
further image processing studies.
Methods: An ADCIS developed innovative system using a 10 mega-pixel digital SLR
camera (approx. 2800dpi), a copy-stand, and a light box to back-light the slides. The
main requirements of the system were: 1. Capture image of the slide frame with patient
identifiers and associated fundus image; 2. Provide detailed index of all images for
quick image filtering and retrieval; 3. Provide the user with full control of camera
settings to ensure the digitized image maintained the fidelity of the slide’s image; and
4. Provide superior system performance than conventional slide scanners (typically
5 minutes/slide at ~2000dpi).
The system software developed by ADCIS and Allergan Inc. meets all these
requirements. It is comprised of two main components: a) Slide Snapper, to capture
slide image and patient data; and b) Slide Display, to query the database and display
images.
Slide Snapper includes a camera driver providing the user with full control of the
camera using a personal computer, and the capability to snap two images of a slide: one
low resolution JPEG image of the frame, and a full resolution, RAW mode image of the
film portion of the slide, later converted to a TIFF image. Slide-Snapper records images
and user-entered patient data into a MySQL database for use by Slide-Display.
Slide Display enables the user to query the index database with advanced selection
and filtering tools to display images and data. User can adjust image brightness,
contrast, zoom, and view stereo pairs (using 3D glasses). Database indexes can be
exported to allow external data sources reconciliation. Index database can be edited
to correct user data entry errors.
Results: Using two of these slide digitization systems, two trained users digitized
78,000 slides during an 81-day period. The resulting database is now online and
accessible on the Allergan campus using the Slide-Display software.
Conclusions: 35 mm fundus slides were scanned at high resolution at a rate of about
1.3 slides per minute using the newly developed digitization system. It is estimated
that two conventional slide scanners would take approximately 2.5 years for the same
set of slides, and this is without capturing the slide frame.
CR: M.E. Verdugo, Allergan Inc., E; P. Nadolny, Allergan Inc., E; J. Buonomo, Allergan
Inc., E; A. Sasai, Allergan Inc., E; B. Lay, ADCIS SA., E; G. Dagniaux, ADCIS SA., E.
Support: None
Purpose: To determine the effect of image averaging on fundus autofluorescence
images taken with a fundus camera.
Methods: Fundus autofluorescence images from 38 eyes of 23 patients were captured
into WinStation™ (Ophthalmic Imaging Systems, Sacramento, CA) using a Topcon
EX fundus camera equipped with an excitation filter of 580 nm (bandwidth 500-610
nm) and a barrier filter of 695 nm (bandwidth 675-715 nm). Each eye had multiple
images taken of the macula which were then processed using an image averaging
algorithm designed by Ophthalmic Imaging Systems to yield a single composite
image. The best single original image was chosen by an unmasked retinal specialist
(MDO) and altered only to match the contrast and brightness of the composite image
for more equivalent comparison. A retinal specialist (JEK) who was masked to the
image processing history then compared the 38 sets of 2 images, without knowing
which was the composite image and which was the single original image. The grading
process included an indication of whether the 2 images in each set were “equivalent”
or one was “superior,” in terms of image quality. When there was a preferred image,
it was rated as “improved” or “greatly improved” compared to the non-preferred
image. Subjective grading criteria included resolution, sharpness, and pathology
determination to yield an overall impression.
Results: All composite images (100%) were rated superior or equivalent to the
corresponding single images by the masked grader. In 35 of the 38 sets of images
(92%), the composite image was judged to be “superior” to a corresponding single
image. The remaining 3 sets (8%) were judged to be “equivalent”. Thirteen composite
images (37%) were rated “greatly improved” while 22 (63%) were rated “improved”. A
second identical reading performed several hours later by the same masked observer
again selected composite images to be “superior” or “equivalent” to single image in all
38 sets. In 36 of 38 sets (95%), there was agreement between first and second reading.
The number of images used to create the composite images did not correlate with the
degree of improvement; the “greatly improved” category included composite images
created from 2 up to 7 original images. A series of images with close registration
yielded superior composite images.
Conclusions: Image averaging can significantly improve the quality of fundus
autofluorescence imaging acquired by a fundus camera even when only two images
are combined.
CR: M.D. Ober, None; J.E. Kim, None; T. Trozak, None; H. Demirci, None.
Support: Supported in part by The CONNECT Network
1839-1842
1843 - D752
Ex vivo Changes in Retinal Pigment Epithelial Autofluorescence With Light
Exposure
1844 - D753
Fast Two-Photon Excited Autofluorescence Imaging of the Neurosensory Retina
and Underlying RPE Cells from Human Donor Eyes
J.J. Hunter1A, J.I.W. Morgan1B, R. Wolfe1A, J.R. Sparrow2, D.R. Williams1B. ACenter for
Visual Science, BInstitute of Optics & Center for Visual Science, 1University of
Rochester, Rochester, NY; 2Department of Ophthalmology, Columbia University,
New York, NY.
O. La Schiazza, J.F. Bille. Kirchhoff Institute for Physics, University Heidelberg,
Heidelberg, Germany.
Purpose: We previously described a reduction and subsequent recovery of macaque retinal
pigment epithelial cell autofluorescence (AF) in vivo following exposure to visible light. To
clarify whether these changes reflect the intrinsic properties of the fluorophores responsible
for AF or are caused by other retinal changes (such as a light-induced migration of a screening
pigment), we investigated whether similar AF changes could also be observed in two
different ex vivo preparations.
Methods: Fixed tissue was imaged in the same adaptive optics scanning laser ophthalmoscope
used in the in vivo studies. Flat-mounted human RPE slides (retina removed) or fixed cultured
A2E-laden ARPE19 cells were placed in the retinal plane of a model eye and exposed to light
of various powers, durations, and wavelengths from the visible to the infrared. Images were
acquired before, immediately after, and up to 24 hours after the light exposure. AF changes
were quantified by the normalized ratio of AF intensity inside the exposed area to control
regions immediately outside the exposed area.
Results: The in vivo and ex vivo experiments produced results that were similar in several
respects. Both revealed a reduction in AF immediately following visible light exposure,
but not with intense infrared exposure. Both showed reciprocity of power and duration,
indicative of a photochemical rather than thermal origin for the effect. Both showed some
recovery of AF subsequent to the reduction that immediately followed light exposure, though
only partial recovery was observed in the ex vivo case. To produce the same AF reduction,
roughly 10 times greater retinal irradiance was required in the in vivo case relative to the
two ex vivo preparations.
Conclusions: The similarities between the in vivo and ex vivo results suggest that the metabolic
activity of the living retina is not required to produce the immediate light-dependent
reduction in AF and suggests that the effect reflects an intrinsic property of the fluorophores
involved. One possible mechanism is the photooxidation of lipofuscin, which could have
damaging consequences for the retina. If this is the mechanism, the fact that the living eye
is 10 times less sensitive to AF changes and that it shows a complete, rather than a partial,
recovery of AF intensity suggests that there may be metabolic mechanisms that actively
protect against light-induced changes in lipofuscin.
CR: J.J. Hunter, Bausch & Lomb, F; J.I.W. Morgan, Bausch & Lomb, F; dual wavelength
imaging, P; R. Wolfe, Bausch & Lomb, F; J.R. Sparrow, None; D.R. Williams, Bausch & Lomb,
Optos, C; adaptive optics, dual wavelength imaging, P; Bausch & Lomb, F.
Support: Bausch & Lomb, NIH EY014375, NIH EY01319, NSF Science and Technology Center
for Adaptive Optics (coop. agr. no.: AST-9876783 with UCSC), NEI Training grant EY07125,
and Research to Prevent Blindness
1845 - D754
Image Fusion Based Resolution Enhancement of Retinal Spectral Domain
Optical Coherence Tomography Images
S. Farsiu1A, B.A. Bower1B, J.A. Izatt1B,1A, C.A. Toth1A,1B. AOphthalmology Department,
B
Biomedical Engineering Department, 1Duke University, Durham, NC.
Purpose: We hypothesize that recent advances in image processing can be used to
generate high-quality spectral domain optical coherence tomography (SDOCT) retinal
images even for non-cooperative patients. SDOCT image sequences are usually captured
as progressively azimuthally translated B-scans, creating a noisy 3D representation of
the retinal layers (volumetric scan). Alternatively, it is possible to capture a sequence of
repeated SDOCT B-scans from a unique azimuthal position, which in a post-processing
step are registered and summed, creating a unique less noisy image (lateral repeated scan).
While for consenting adults, the azimuthal and lateral resolutions of SDOCT scans are
often acceptable, in imaging infants or severely impaired adults, the uncontrolled rapid
patient motion limits the acquired resolution as defined by the number of the B-scans in
the volumetric or the number of A-scans in the lateral repeated scanning scenarios.
Methods: Novel image fusion methodologies were used to create images with high
azimuthal and lateral resolutions. For the volumetric scanning scenario, instead of
capturing a single time-consuming high-density 3D scan, we propose to capture several
volume scans each with significantly fewer B-scans. As each sparsely sampled sequence is
acquired relatively fast, patient motion artifacts are minimal. By exploiting known camera
synchronization principles, these artifact-free sequences are registered and interlaced,
creating a dense volumetric retinal representation. Alternatively, for the lateral repeated
scanning scenario, fast B-scans with fewer A-scans can be captured. These low-resolution
B-scans are then registered and interpolated, creating a less noisy B-scan with higher
number of A-scans, compared to each individual B-scan.
Results: For the volumetric scenario, two sparsely sampled SDOCT sequences of a patient
retina were fused creating a denser 3D representation; the experiment was successfully
repeated for fusing three such sequences. For the lateral repeated scanning scenario, images
of a retina phantom with 250 A-scans were fused, creating an image with 1000 A-scans
with reduced noise artifacts compared to each original frame.
Conclusions: A proof of concept for using modern image fusion algorithms to create
high quality images from fast sparsely sampled scans is provided. We believe, this
pioneering work will be used as a stepping stone toward many other image fusion based
ophthalmic SDOCT system designs, aimed at patients with uncontrollable motion or
pediatric imaging.
CR: S. Farsiu, Bioptigen, Inc., F; B.A. Bower, Bioptigen Inc., I; Bioptigen Inc., C; J.A.
Izatt, Bioptigen, Inc., F; Bioptigen, Inc., I; Bioptigen, Inc., E; Bioptigen, Inc., P; C.A. Toth,
Genentech, Bioptigen Inc., Sirion, Alcon Laboratories, F; Alcon Laboratories, P.
Support: NIH SBIR 2R43EY018021-01 with Bioptigen with a subcontract; and the North
Carolina Biotechnology Center Collaborative Funding Grant #2007-CFG-8005. Anjum
F. Koreishi provided imaging support.
Purpose: Two-photon excited fluorescence imaging offers a number of advantages
compared to convential single-photon excited fluorescence screening methods, e.g.
large sensing depth, minimized photo damage and intrinsic 3D-resolution without
the need of a confocal pinhole. The present study focuses on the implementation of
two-photon microscopy combined to a fast resonant ophthalmologic scanner for a
possible application in the human eye for retinal disease diagnostic.
Methods: A Ti:Sapphire (830 nm, 150 fs, 76 MHz) (Mira 900F, Coherent) fs-laser
was coupled to a conventional laser scanning ophthalmoscope (Heidelberg Retina
Tomograph HRT). The neurosensory retina and underlying RPE cells from human
donor eyes were imaged in two-photon exited autofluorescence. The autofluorescence
signal is separated from backscattered light using a dichroic beamsplitter combined
with appropriate shortpass filters.
Results: Two-photon excited autofluorescence signals could be detected from the
photoreceptors outer as well as inner segments. Furthermore the retinal nerve
fiber layer and the underlying ganglion cells could be imaged using two-photon
excited autofluorescence. Accumulated lipofuscin in the RPE cells shows a strong
autofluorescent signal that could be excited and detected through the super-imposed
neurosensory retina when excited with NIR fs-laser light.
Conclusions: Two-photon imaging of intrinsic retinal fluorophores allows to study
a broad range of pathological and morphological defects in the retina with higher
resolution and less photo- and thermal out-of-focus damage compared to a singlephoton blue light excitation. The neurosensensory retina contains autofluorescent
markers that enable direct visualization of retinal health and can be used for
diagnostic and monitoring of retinal diseases. Excitation of the RPE cells through
the neurosensory retina by NIR laser light, generates enough fluorescence signal for
a quantitative estimation of RPE’s lipofuscin content.
CR: O. La Schiazza, None; J.F. Bille, None.
Support: None
1846 - D755
A Comparison of Fourier Domain , Slitlamp Mounted, Optical Coherence
Tomography Scans With Scans Made by an OCT Stratus (Zeiss) , and a 3D
OCT-1000 (Topcon)
F.D. Verbraak1A,1B, P.H.B. Kok1B, D.J. Faber1A, H.R. de Vries2, H.W. van Dijk1B, M.E.J. van
Velthoven1B, T.G. van Leeuwen1A. ALaser Center, BDpt. of Ophthalmology, 1Academic
Medical Center, Amsterdam, The Netherlands; 2Topcon Europe BV, Capelle a/d
IJssel, The Netherlands.
Purpose: To compare images made with a new FD-OCT device, mounted on a slitlamp
with images of the same region made with OCT Stratus (Zeiss), and 3D OCT-1000
(Topcon).
Methods: Images were made in selected patients, with representative macular
pathology with a newly developed FD OCT scanning device integrated into a common
slitlamp (figure 1). OCT characteristics: central wavelength 830 nm, bandwidth 30
nm, resolution in tissue 8 micron, scanning speed 1000 a-scan per sec, one b-scan in
0.2 sec, scandepth 2 mm. Scans are made through a handheld lens (Volk 60 D), while
simultaneously the (lesion in the) retina can be observed, with the slitlamp. A color
fundus photography of the observed area is made at the same time (Topcon camera
DC1, resolution = 3.24 Mp).
In the same patients line scans were made with the OCT Stratus and 3D volumes scans
were made with the 3D OCT-1000. Scans made at approximately the same location
were subjectively compared with respect to quality of the images.
Results: With the new device scans could be made without difficulty in all patients
with a reasonably clear retinal image on slitlamp examination. Examples of scans
made with the 3 devices of patients are shown. (see figure 2 to 5). The quality of the
scans made with the new device is better than the OCT Stratus, and slighly less than
the 3D OCT-1000.
Conclusions: Quality of the scans made with the new device compare favourably
with TD-OCT images (OCTStratus, Zeiss), and are slightly less than scans made
with dedicated FD-OCT systems. The ease of use and the instanteneous availablity
of results of OCT examination, during a regular clinical examination, could be very
usefull in daily practice.
CR: F.D. Verbraak, None; P.H.B. Kok, None; D.J. Faber, None; H.R. de Vries, Topcon
Europe BV, E; H.W. van Dijk, None; M.E.J. van Velthoven, None; T.G. van Leeuwen,
Topcon Europe BV, F.
Support: None
1843-1846
1847 - D756
Novel B-Mode Spectral Optical Coherence Tomography: Mirror-Term Free 3D
Imaging of Retinal Structure and 3D Doppler Tomography
1848 - D757
Wavefront Control of Dual-Deformable-Mirror Adaptive Optics for Scanning
Laser Ophthalmoscope
R.A. Leitgeb1,2A, T. Schmoll1, R. Michaely2B. 1Center of Biomed. Eng. and Physics,
Medical University of Vienna, Vienna, Austria; ALaboratoire d’Optique
Biomedicale,, BLaboratoire d’Optique Biomedicale, 2Ecole Polytechnique Federale
de Lausanne, Lausanne, Switzerland.
W. Zou, X. Qi, S.A. Burns. School of Optometry, Indiana University, Bloomington,
IN.
Purpose:To apply a novel and cheap B-mode spectral optical coherence tomography
system for mirror-term suppression without additional phase-shifting devices and for
Doppler imaging of retinal blood flow based on resonant Doppler tomography.
Methods:B-mode phase sensitive SOCT uses a carrier phase offset to reconstruct the
full complex SOCT signal. The complex signal is produced by analytic continuation of
the measured real valued data with its Hilbert transform along the B-scan coordinate.
The mirror term free structure is obtained by standard Fourier transform of each
complex valued A-scan. The novel approach is to introduce the carrier phase by
simply offsetting the beam on the transversally fast scanning galvo-mirror. Hence,
no expensive phase shifting devices are needed, and the method is easily integrated
into any existing SOCT platform. The dynamic phase offset is effectively a Doppler
frequency introduced through the scanning. By tuning the scanning Doppler
frequency to that of retinal flow, the latter can be enhanced by virtue of resonant
Doppler tomography. On the other hand static signals will be attenuated for large
Doppler offsets due to fringe washout, which yields optical vivisectioning of retinal
perfusion without elaborate image post-processing.
Results:High-speed mirror-artifact free retinal tomograms have been recorded of
healthy subjects with the novel B-mode SOCT system at 20kHz A-scan rate and a center
wavelength of 820nm. Studying the performance for mirror term suppression shows
an optimal phase shift of π/2 between adjacent A-scans ( >30dB suppression). The
method is capable to correct for slight phase errors due to subject motion. For phase
shifts >π one observes suppressed static structure signals as well as enhanced flow
signals. The lateral scanning direction is directly related to the axial flow direction
that will be enhanced. We recorded directionally resolved 3D flow maps of the optic
nerve head of a healthy subject in-vivo.
Conclusions:The potential of a novel and cheap method to perform 3D in-vivo retinal
tomography and its capability for 3D optical vivisectioning of retinal perfusion is
demonstrated. The method is easily integrated into any SOCT platform including
swept source OCT. The performance of the method in the presence of large motion
artifacts needs further investigation. Nevertheless, B-mode SOCT is less sensitive to
motion artifacts than state-of-the art phase sensitive SOCT.
CR: R.A. Leitgeb, None; T. Schmoll, None; R. Michaely, None.
Support: FNS Grant 205321-109704/1; European FP7 Grant 201880 FUNOCT
Purpose: To develop a wavefront control algorithm for dual-deformable-mirror
(DDM, including woofer-tweeter) adaptive optics. This research tests the algorithm
for implementation in a new DDM adaptive optics scanning laser ophthalmoscope
(AOSLO) under development.
Methods: The next generation AOSLO will have two (or more) deformable mirrors
(DMs) instead of one DM. Typically, one DM will be a low order, high-stroke mirror
(the woofer), and the other one will be a high-order, low-stroke mirror (the tweeter).
An AOSLO system with the woofer-tweeter DMs is expected to have a better
wavefront correction performance for high-resolution retinal imaging. Specifically,
the experimental system under development is composed of a superlum diodes (SLD)
point light source with central wavelength of 676.6nm, a Boston Micro DM (maximum
stroke 2.5 µm), a Mirao-52d magnetic DM (maximum stroke 50μm), and a lenslet array
directly coupled onto a digital CCD camera.
We developed a new wavefront control algorithm, which is based on applying the slope
measurements from one wavefront sensor to command two DMs to work together for
correcting wavefront distortions in real time. The algorithm acts to decompose the
estimated wavefront shape into two parts: one part is the low order aberrations which
will be corrected by the Mirao-52d DM, and the other part is the high order aberrations
to be corrected by the Boston Micro DM. Instead of separating the woofer and tweeter
correction into two independent control processes as adopted in previous algorithms,
we couple the dual-DM corrections together as a whole in a single control process,
while the Mirao-52d DM still contributes to the low-spatial-frequency correction
and the Boston Micro DM contributes to the high-spatial-frequency correction. The
stroke amplitude of the low-frequency aberrations under control, such as wavefront
defocus, is determined by a combination of a manual control (to set the plane of focus
within the retina) and from slope measurements (to correct the ammetropia of the
eye). In practice, a weighting factor is chosen to balance the wavefront corrections
between the two DMs.
Results: The mathematical framework of the proposed algorithm is simple.
Theoretical analysis and simulations shows that this dual-process control is stable
and efficient.
Conclusions: A real-time wavefront control algorithm for DDM adaptive optics for
SLO is proposed. By combining the control of two mirrors and a single wavefront
sensor into a single control system we will be able to obtain real time control of both
low order and high order aberrations over a wide dynamic range.
CR: W. Zou, None; X. Qi, None; S.A. Burns, None.
Support: NIH-NEI Grant EY 14375
1847-1848
Monday, April 28, 3:00 PM - 4:45 PM Palm A Symposia Program Number Range: 1998-2003
271. Linking Retinal Structure and Visual Function - Minisymposium Organizing Section: VI
1998 - 3:00PM
Does the Retinal Mosaic Limit Visual Resolution?
1999 - 3:15PM
Adaptive Optics Scanning Laser Ophthalmoscopy Imaging in Patients with
Retinal Degenerations
D.I.A. MacLeod. UCSD, La Jolla, CA.
J.L. Duncan1, A.J. Roorda2. 1Beckman Vision Ctr-Sch of Med, Univ of California - SF,
San Francisco, CA; 2School of Optometry, Univ of California - Berkeley, Berkeley, CA.
Purpose: To image microscopic retinal structures, including individual retinal
pigmented epithelial (RPE) cells, in living human eyes with retinal degenerative
disease using high resolution imaging techniques.
Methods: Adaptive optics scanning laser ophthalmoscopy (AOSLO) was used to
image the macular region in 6 patients with retinal degenerative diseases including 2
patients with cone-rod dystrophy (CRD), 1 with retinitis pigmentosa due to a rhodopsin
mutation, 1 with Usher Syndrome type 2 and 2 with bilateral progressive maculopathy,
in addition to 9 age-related normal subjects. The AOSLO used a low-coherent 840
nm light source for imaging over a 1.2 degree field of view at 30 frames per second.
Images were generated from video sequences from which larger field montage images
were constructed. Custom written software was used to determine spatial statistics
of cell arrays in the images. A Nidek MP1 fundus-guided microperimeter was used
to correlate visual function with the visible structure.
Results: In patients with retinal degenerative diseases, AOSLO images revealed
patches of intact cone photoreceptors separated by areas with arrays of hexagonal
structures, presumably RPE cells, in regions where it appeared that cones were
missing. In a CRD patient with advanced disease, the RPE cells were visualized in
an annular region surrounding a cone-preserved central area. In the other patients
the appearance of RPE cells was more sporadic, appearing in patchy areas where the
cone mosaic was not visualized. The RPE cell shape, size and distribution compared
well with measurements from the literature. Fundus-guided microperimetry results
indicated scotomas that corresponded to the locations where RPE cells were visible.
RPE cells in were not visible in any of the normal subjects.
Conclusions: We have directly visualized the mosaic of RPE cells in patients with
retinal degenerative diseases using an AOSLO. RPE cells were not seen in normal
subjects, presumably because they were masked by the presence of a contiguous
array of intact photoreceptors. In patients with retinal degeneration, photoreceptor
loss permitted visualization of RPE cells. Regions with visible RPE cells demonstrated
loss of visual function measured using microperimetry.
CR: A.J. Roorda, University of Houston, University of Rochester, P.
CT: www.clinicaltrials.gov, NCT00254605
2000 - 3:30PM
Linking Structure and Function in Glaucoma
2001 - 3:45PM
In vivo Optophysiology: Depth Resolved Measurement of Intrinsic Optical
Signals in Human Retina by Optical Coherence Tomography
R.S. Harwerth, J.L. Wheat, N.V. Rangaswamy. College of Optometry, University of
Houston, Houston, TX.
Purpose: To determine whether models to derive quantitative relationships between
clinical measures of glaucomatous neuropathy, which were developed from data on
experimental glaucoma in macaque monkeys and normative data for human patients,
can be applied to link the structural and functional defects of patients with clinical
glaucoma. Methods: Visual fields by standard automated perimetry (SAP SITA
24-2) and retinal nerve fiber layer (RNFL) thickness measures by optical coherence
tomography (OCT) were obtained for both eyes of 54 control subjects (ages 20 - 80)
and 30 patients with glaucoma (ages 33 - 86). The measures of visual sensitivity and
RNFL thickness were each used to estimate neuronal populations and the degree
of agreement between subjective and objective measurements was evaluated by the
goodness-of-fit to a one-to-one relationship. Results: For the control subjects and
for patients with early glaucoma, the model developed with experimental glaucoma
and normative clinical data produced highly correlated estimates of retinal ganglion
cells (RGCs), with a near 1:1 relationship between SAP and OCT data. With more
advanced disease, the unity relationship broke down and SAP estimates indicated
greater RGC loss than OCT estimates. Concurrence between estimates required a
stage-dependent variable for axonal density in the RNFL. Conclusions: The studies
demonstrated that SAP measurements of visual sensitivity and OCT measurements
of RNFL thickness are correlated measures of the underlying populations of RGCs.
The model to derive RGCs from corresponding visual field locations and RNFL sectors
produced agreement between these two methods of assessing retinal neurology,
both for retinas with normal populations of RGCs and for retinas with progressively
decreased populations of RGCs from the neuropathy glaucoma. Thus, the results
establish that there is a strong link between structure and function in normal and
defective vision from glaucoma,which can be quantified by translation of the clinical
measurements to a common parameter related to RGC densities
Supported by NEI grants R01 EY01139, P30 EY07751, and T32 EY07024
CR: R.S. Harwerth, None; J.L. Wheat, None; N.V. Rangaswamy, None.
A.R. Tumlinson, B. Hermann, B. Povazay, T.H. Margrain, A. Binns, B. Hofer, W. Drexler.
School of Optometry and Vision Sciences, Cardiff University, Cardiff, United
Kingdom.
Purpose:To evaluate the feasibility of functional optical coherence tomography (fOCT)
for non-invasive depth resolved optical mapping of the physiological response of the
human retina to light stimulus in vivo and to compare the outcome with reported
retinal intrinsic optical signals (IOS).
Methods:Spatially encoded frequency domain OCT at 1050 nm for high speed (up
to 47000 A-scans per second) high resolution retinal imaging has been interfaced to
an ophthalmic OCT system equipped with a head rest and a bite bar, visible light
stimulus, and readied for simultaneous ERG measurements. The time resolution of
the OCT system is about 20 μs. After dark adaptation the dilated eyes were stimulated
with a white light pattern stimulus of varying time, intensity and spatial pattern.
Reflectivity profiles were recorded with OCT volume scans, partly overlapping with
the stimulated area. The examined volume was 10ºx1.6º at different locations; ~15º
(rod dominant) and ~1º (cone dominant). Measurements were taken on different time
scales, directly after the stimulus to examine fast changes on a ms scale, as well as on
a minute scale over 30 minutes to account for slow changes. To reduce the influence of
eye motions and physiological noise dedicated post processing techniques for signal
extraction have been evaluated.
Results:Non-contact, optical probing of retinal physiological response with ~7 μm
axial and ~20 μm transversal resolution to visual stimulation was demonstrated in
vivo in normal healthy eyes using functional ultrahigh resolution optical coherence
tomography. Our results describe the relationship between electrophysiological
and optophysiological responses in humans. Possible explanation of the detected
optophysiological signals in the photoreceptors includes hyperpolarisation or altered
metabolic rates that cause changes in the mitochondrial refractive index.
Conclusions:Optophysiology, a functional extension of ultrahigh resolution OCT
has been extended from ex vivo preparations to living humans. Progress has been
made in instrument design, experimental protocol, and signal processing that has the
potential to establish this technique as an optical analogue to electrophysiology, by
detecting depth resolved variations in optical backscattering caused by physiological
tissue changes.
CR: A.R. Tumlinson, None; B. Hermann, None; B. Povazay, None; T.H. Margrain,
None; A. Binns, None; B. Hofer, None; W. Drexler, Carl Zeiss Meditec Inc., F.
Support: Cardiff University, FP6-IST-NMP-2 STREPT (017128), DTI grant (OMICRON)
and AMR grant (AP1110), Carl Zeiss Meditec Inc.
1998-2001
Monday, April 28, 3:00 PM - 4:45 PM Palm A Symposia Program Number Range: 1998-2003
271. Linking Retinal Structure and Visual Function - Minisymposium Organizing Section: VI
2002 - 4:00PM
Non-Invasive Imaging of Optic Nerve Head as an Indication of Retinal
Pathology
2003 - 4:15PM
Contribution of Retinal Ganglion Cells to Intrinsic Signals in Retinal Optical
Imaging by Trans-Corneal Electrical Stimulation or by Light Stimulation
H. Primack1, Z. Burgansky-Eliash2,1, D.A. Nelson1, M. Neudorfer3, O. Pupko1, A.
Grinvald4. 1Optical Imaging Ltd., Rehovot, Israel; 2Department of Ophthalmology,
The Edith Wolfson Medical Center, Holon, Israel; 3Department of Ophthalmology,
Sourasky Medical Center, Tel-Aviv, Israel; 4Department of Neurobiology,
Weizmann Institute of Science, Rehovot, Israel.
T. Fujikado1A, Y. Okawa1A, T. Miyoshi1B, Y. Hirohara2, T. Mihashi2, Y. Tano1C. ADept of
Applied Vis Science, BDept of Physiology, CDept of Ophthalmology, 1Osaka Univ
Medical School, Suita, Japan; 2Topcon Research Institute, Tokyo, Japan.
Purpose: The Retinal Function Imager (RFI, Optical Imaging, Rehovot, Israel), is a
fundus camera modified to deliver a fast train of flashes and process the resulting
images. Recently, a novel illumination-dependent enhanced darkening signal of
the optic nerve head (ONH) was observed using the RFI. We evaluated this signal
quantitatively, and compared it between glaucoma and non-glaucoma subjects.
Methods: The RFI illumination consisted of train of 8 strong stroboscopic flashes
(< 1 msec), 17.5 ms apart. The broadband emitted light (xenon bulb) was filtered
with a 548bp75 filter. Seventeen eyes of 14 glaucoma patients, 15 eyes of 9 patients
with age related macular degeneration (AMD), 8 eyes of 7 patients with diabetic
retinopathy (DR), and 22 eyes of 13 healthy volunteers were recruited. All subjects had
a detailed ophthalmic examination and RFI imaging of the ONH after pupil dilation.
All glaucoma and healthy subjects had also a visual field test; glaucoma diagnosis
was established by visual field criteria.
Results: The first image in each train does not include any response to the retinal
photic illumination, because the flash duration is shorter than 1 msec. Therefore,
ratio comparisons (image #2 / image #1) reveal differences due to relative darkening
of the ONH in response to the retinal photic illumination. Stronger darkening was
observed in glaucoma patients compared to healthy, DR and AMD subjects. The
largest quantified ONH darkening values for glaucoma patients were about 4 fold
larger than the typical values observed for other subjects.
Conclusions: We found a new darkening signal of the ONH in response to illumination.
This signal varies substantially in relation to the glaucomatous state of respective
subjects’ eyes.
CR: H. Primack, Optical Imaging Ltd., E; Z. Burgansky-Eliash, Optical Imaging
Ltd., E; D.A. Nelson, Optical Imaging Ltd., E; Optical Imaging Ltd., P; M. Neudorfer,
None; O. Pupko, Optical Imaging Ltd., E; A. Grinvald, Optical Imaging Ltd., I.
Support: None
Purposes: The origin of intrinsic signals in the retinal optical imaging is not well
determined. In the case of light stimulation, the intrinsic signal is originated principally
in the outer retina and the contributions of retinal ganglion cells (RGCs) is reportedly
small (Tso DY et al, ARVO 2006).In the case of retrograde electrical stimulation of
RGCs, the evoked intrinsic signal at optic disc (OD) disappeared completely after the
injection of tetrodotoxin (TTX) suggesting that RGCs have at least some contribution to
the retinal intrinsic signal. (Okawa Y, et al ARVO 2007). In this paper, we investigated
the contribution of RGCs to the intrinsic signal in the case of trans-corneal electrical
stimulation (TcES) and light stimulation (LS).
Methods: Three eyes of three cats were studied under general anesthesia. For
TcES, the electrical current was applied from the fixed frame with rectangular,
train of 20 paired biphasic pulses. For LS, 4 cycles/degree black and white squares
alternating at 8 Hz were projected as a vertical bar for 4 sec. Fundus images in the
near-infrared (800-880nm) were obtained in every 25msec between 2 seconds before
and 20 seconds after stimulation. Two-dimensional topography of reflectance change
(RC) was constructed by subtracting images before stimulation from those after
stimulation. Experiments were carried out before and after TTX (5mM, 20ul) injection
intravitreally.
Results: RC was observed at OD by TcES (-0.45% at 1.0mA) and both at OD (-0.25%),
and light-stimulated retina (LSR, -0.75%) by LS. After TTX application, the RC at
OD disappeared almost completely by TcES and LS but those at LSR by LS reduced
only 15-20%.
Conclusions: The blockage of RGC activity by TTX extinguished the RC at optic disc,
suggesting that the intrinsic signal at optic disc may represent the activity of RGCs
and could be used to evaluate the RGCs functionally.
CR: T. Fujikado, None; Y. Okawa, None; T. Miyoshi, None; Y. Hirohara, Topcon Co.,
E; T. Mihashi, Topcon Co., E; Y. Tano, None.
Support: MHLWJ Grant 18591918
2002-2003
Monday, April 28, 3:00 PM - 4:45 PM Hall B/C Poster Session Program Number/Board # Range: 2257-2266 / D805-D814
290. Anterior Segment Imaging Organizing Section: VI Contributing Section: MOI
2257 - D805
High Resolution Non-Invasive Imaging of the Cornea by Epi-Detected Second
Harmonic Generation and Third Harmonic Generation
2258 - D806
Minimal-Invasive Imaging of Ocular Surface Pathologies - Confocal vs. TwoPhoton Microscopy
L. Jay1, A. Brocas1,2, K. Singh1,2, I. Brunette2,3, T. Ozaki1. 1INRS-EMT, Varennes, QC,
Canada; 2Maisonneuve-Rosemont Hospital Research Center, Montreal, QC,
Canada; 3Ophthalmology, University of Montreal, Montreal, QC, Canada.
M. Mueller1A, G. Huettmann1B, N. Koop1B, P. Steven1A,1C. AEye Clinic, BInstitute of
Biomedical Optics, CInstitute of Anatomy, 1University of Luebeck, Luebeck,
Germany.
Purpose: Advances in femtosecond laser have permitted significant progress in
corneal refractive surgery. Additional progress will require non-invasive imaging
that offers high spatial resolution across the entire corneal thickness. For clinical
applications, imaging in the epi-direction (i.e. from the epithelial side) is also of
fundamental importance. In this study, we showed that second harmonic generation
(SHG) and third harmonic generation (THG) can be used in combination to perform
high resolution imaging of full thickness ex vivo pig corneas.
Methods: The laser source used for harmonic generation imaging was a solidstate mode-locked Yb:KGW oscillator (t-Pulse 20; 1030nm, 1000mW, 200fs, 50MHz;
Amplitude-Systemes). The nonlinear optical imaging system was an upright microscope
built using opto-mechanical parts (AFOptical). Fresh pig eyes were obtained from
a slaughterhouse within 6 hours of death and kept in a humid chamber at 4 degrees
C until used. In some of these eyes, intrastromal lamellar laser cuts were performed
using a chirped-pulse amplification Ti:sapphire laser (KMLabs), in order to document
the quality of SHG and THG imaging of these cuts.
Results: SHG and THG signals provided complementary information since second
harmonic was generated only in the stroma, while third harmonic was also generated
at the level of epithelial and endothelial layers. Both SHG and THG were detected
forward and backward accross the entire thickness of the tested corneas, allowing
high resolution imaging of the natural structures of the epithelium, stroma and
endothelium (e.g. cells, collagen fibres). The laser cuts created by the femtosecond
laser were also clearly visualized.
Conclusions: We have demonstrated that the combination of SHG and THG offers
unique opportunities for the development of new non invasive microscopy tools
for corneal imaging. Moreover, THG offers an alternative to the auto-fluorescence
which depends on the presence of NADPH, since third harmonic is generated by
any optical inhomogeneities of the cornea. The ability to obtain both SHG and THG
signals in epi-detection on fresh eyes gives promising hopes for application of these
techniques to clinical studies.
CR: L. Jay, None; A. Brocas, None; K. Singh, None; I. Brunette, None; T. Ozaki,
None.
Support: CIHR, NSERC, FRSQ
Purpose: Minimal-invasive imaging of ocular surface pathologies may give beneficial
information prior to surgical procedures. We here compare already established
confocal laser scanning microscopy with two-photon microscopy, a new optical
method for minimal-invasive high resolution imaging.
Methods: Patients presenting ocular surface pathologies such as pterygium,
pannus, conjunctival cysts, papilloma, nevus and pingueculum were examined
with the Rostock Cornea Module (Heidelberg Engineering, Germany) prior to surgery.
Immediately after the procedure the excised pathologies were examined by twophoton microscopy (DermaInspect, Jenlab, Germany) without previous fixation and
tissue processing. Images were generated by exciting autofluorescence at different
wavelengths. Fluorescence-lifetime imaging (FLIM) and Second Harmonic Generation
(SHG) were conducted additionally. After two-photon microscopy, excised pathologies
were fixed and processed for histopathological examination.
Results: High resolution reflection images, generated by laser scanning confocal
microscopy, demonstrate tissue components as epithelial cells, connective tissue
fibres and deposits, blood vessels and erythrocytes. Two-photon microscopy of
corresponding tissue structures allows to estimate the nucleoplasmic index, to
identify macrophages and to distinguish cellular from acellular components by
wavelength modulation and Second Harmonic Generation. Fluorescing-lifetime
imaging (FLIM) allows to differentiate goblet cells and nevus cells from epithelial
cells of the conjunctiva.
Conclusions: This is the first study to compare confocal with two-photon microscopy
regarding ocular surface pathologies. Laser scanning confocal microscopy features
advantages such as rapid image formation and real-time imaging of large tissue areas
whereas two-photon microscopy enables additional characterization of individual
cell types and tissue components by wavelength adjustment, FLIM and SHG. Possible
applications could comprehend a general preoperative tissue examination by confocal
microscopy and an additional two-photon examination of selected tissue components
for in-detail analysis of pathological changes.
CR: M. Mueller, None; G. Huettmann, None; N. Koop, None; P. Steven, None.
Support: University of Luebeck Medical Technology Grant A6
2259 - D807
Age-Related Changes of Human Limbus on in vivo Confocal Microscopy
2260 - D808
Three Dimensional Endoscopic Confocal Corneal “Fly Through” Video for
Qualitative Analysis of the Cornea Following AcuFocusTM Corneal Inlay
T. Zheng, J. Xu. EYE and ENT Hospital of Fudan University, Shanghai, China.
Purpose: To demonstrate age-related changes in the microenvironment of limbal stem cells
(LSCs) and analyze the quantity and proliferative potential of the limbal basal epithelial
cells (LBECs) by in vivo confocal microscopy.
Methods: 160 eyes of 160 healthy subjects were enrolled in this study after a routine slit-lamp
examination. They were divided into four groups according to the age: A (0~19), B (20~39),
C (40~59) and D(over 60). In vivo confocal microscopic examination was performed on the
inferior limbus and the images were recorded. For each group, the positive rates of Vogt
Palisades were analyzed to evaluate the microenvironment of LSCs. The average size of
LBECs was measured to assess their proliferative potentials.
Results: The rate of Vogt Palisades in group A,B,C,D were 97.5% (39/40), 95.0% (38/40) ,77.5%
(31/40) ,40.0% (16/40) respectively, showing a significant decreasing tendency with age. Typical
Vogt palisades were found in almost all subjects under 40, with a wavy epithelium-stromal
boundary or alternant epithelium-stromal cords, a bright “purfle” of hyper-reflective basal
epithelial cells, and a slender blood vessel along each stromal papillae (Fig A,B). In contrast,
Vogt Palisades were not observed in nearly two thirds of subjects over 60, with thinner
epithelium, flat epithelium-stromal boundary, and big vessels in the stroma. The hyperreflective basal epithelial cells were replaced by relatively dark ones with invisible nuclei and
clear borderline (Fig E,F). Moreover, eight subjects in group C and D manifested a transiting
morphology named “atrophic Vogt Palisades”, with a slight wavy epithelium-stromal
boundary and decreasing reflection of basal cells (Fig C,D). The average size of LBECs in group
A,B,C,D were (9.89±1.12) μm,(10.65±1.45) μm,(10.70±1.39) μm and (12.36±1.68)μm. Significant
differences between groups were obvious except for that between groups B and C.
Conclusions:The microenvironment of limbus degenerated with age. So did the qualities of
LBECs, with average cell size enlargement and proliferative potential degeneration.
G.O. Waring, IV1, D.S. Durrie1, J.E. Sutphin, Jr. 2, J.E. Stahl1. 1Ophthalmology, Univ.
of Kansas Med.Center/Durrie Vision, Kansas City, MO; 2Ophthalmology, Univ. of
Kansas Med.Center, Kansas City, MO.
Purpose: To demonstrate qualitative analysis of the corneal anatomy following
AcuFocusTM corneal inlay (Irvine, CA) using three and four dimensional endoscopic
confocal renderings.
Methods: A single patient with a unilateral AcuFocus corneal inlay underwent
confocal microscopy with the ConfoScan 4 (Nidek, Inc., Fremont, CA) using the Z-ring
for ocular stabilization, a single scan pass and a 2 micron step size. The same technique
was used with a normal cornea for comparison. A three dimensional endoscopic
confocal corneal “fly through” video was created with Analyze software version 7.0
(Biomedical Imaging Resource Mayo Clinic, Rochester, MN). Videos were analyzed and
compared by two independent observers for evidence of keratocyte hypercellularity,
inflammatory cells and changes to the overlying epithelium.
Results: We demonstrate a novel technique for qualitative confocal analysis of a
cornea with an AcuFocusTM corneal inlay. When compared to the control eye, the
endoscopic confocal “fly through” videos demonstrated a well tolerated implant with
lack of surrounding keratocyte hypercelluarlity, inflammatory cells or alteration to the
overlying epithelium. This technique provides the unique ability to view the spatial
relationship of the implant and surrounding cellular layers.
Conclusions: The three dimensional endoscopic confocal corneal “fly through” video
is a novel and useful tool for qualitative analysis of the impact of the AcuFocusTM
corneal inlay on corneal physiology. Although only a single eye was reported, confocal
microscopy demonstrated that the AcuFocusTM corneal inlay appears well tolerated
in the human cornea.
CR: G.O. Waring, None; D.S. Durrie, AcuFocus, C; J.E. Sutphin, AcuFocus, C; J.E.
Stahl, AcuFocus, C.
Support: None
CR: T. Zheng, None; J. Xu, None.
Support: Scientific Research Grants of Bureau Public Health of Shanghai 2006014 and Health
and Science Grants of Bureau Social Development of Pudong New Area PKJ2007-Y13
2257-2260
2261 - D809
Monitoring Nerve Regeneration in Corneal Diabetic Neuropathy With Corneal
Confocal Microscopy
2262 - D810
Factors Associated With Scleral Spur Visibility in Anterior Segment Optical
Coherence Tomography (ASOCT)
E. Midena1,2, S. Vujosevic2, S. Miotto1, M. Cortese1, E. Benetti1, A. Ghirlando1.
1
Ophthalmology, University of Padova, Padova, Italy; 2Fondazione GB Bietti,
IRCCS, Roma, Italy.
S.K. Dorairaj1,2, J.J. Rousso2, C.Y. Cheung3, H.-T. Li 3, R. Ritch1,4, C.-P. Pang3, D.S. Lam 3,
C.K. Leung3. 1Einhorn Research Center, New York Eye and Ear Infirmary., New
York, NY; 2Department of Surgery, Beth Israel Medical Center of the Albert Einstein
College of Medicine., New York, NY; 3The Chinese University of Hong Kong,
Shatin, Hong Kong; 4New York Medical College, Valhalla., New York, NY.
Purpose: Corneal diabetic neuropathy (CDN) is a hallmark of peripheral diabetic
neuropathy. In this study, we investigate corneal subbasal nerve plexus changes in
CDN using corneal confocal microscopy .
Methods: 30 consecutive diabetic patients affected in both eyes by CDN ( subasal plexus
nerve changes) were investigated and followed using corneal confocal microscopy
(Confoscan4, Nidek, Japan). A new validated technique for subasal nerve plexus
detection and examination was applied. Corneal confocal microscopy parameters
for nerve changes were: number and density of nerve fibers, nerve tortuosity and
branching, number of nerve beadings. Two masked examiners evaluated and
quantified corneal confocal microscopy images.
Results: Corneal confocal microscopy allowed in all cases a quantitative analysis of
subbasal nerve plexus. Intra and inter-examiner agreement for confocal microscopy
images were almost perfect (k= 0.95 and 0.92 , respectively). Significant Increase
of nerve beadings (p <0.005) and reduction in nerve tortuosity ( p<0.004) were the
distinctive parameters of nerve regeneration. Increase of nerves density and fibers
was a late phaenomenon.
Conclusions: These results show that corneal confocal microscopy is the key diagnostic
technique in evaluating and monitoring CDN. Quantification of corneal subbasal
nerve plexus parameters allows a correct, reproducible and objective, in vivo, non
invasive approach to CDN, allowing to characterize peripheral diabetic neuropathay,
a potentially highly diasbling complication of diabetes.
CR: E. Midena, None; S. Vujosevic, None; S. Miotto, None; M. Cortese, None; E.
Benetti, None; A. Ghirlando, None.
Support: None
2263 - D811
High Resolution Anterior Segment Spectral Optical Coherence Tomography for
the Imaging of Subtle Alterationsi In the Corneal Structure in Real Time
A. Cervino1, D. Bansal2, R. Montes-Mico1, J.J. Kaluzny3. 1Optics, University of Valencia,
Burjassot, Spain; 2Optopol Technologies S.A., Zawiercie, Poland; 3Institute of
Physics, Nicolaus Copernicus University, Torun, Poland.
Purpose: To determine the clinical value of high resolution anterior segment spectral
optical coherence tomography (SOCT Anterius, Optopol Technology S.A., Poland)
for the in-vivo imaging and observation of subtle corneal structural alterations in
real time.
Methods: Four patients with different corneal conditions were examined with the
new anterior segment spectral domain OCT: 4 years after penetrating keratoplasty,
Fuchs dystrophy, post- refractive surgery for myopia (PRK) and advanced granular
corneal dystrophy. The system uses a 870nm wavelength for high resolution high
speed observation of anterior segment structures with an axial resolution of 3μm
and lateral resolution of 7μm. It provides 25000 A-scans per second, with a scanning
density of 3500 A-scans per mm.
Results: Although there is a frame size limitation, imaging of small corneal segments,
higher resolution allowed observation of structures showing levels of detail not
achieved with previous anterior segment OCT devices available, allowing the
determination of location and size of corneal structures, epithelial corneal thickness
and even corneal transparency grading.
Conclusions: Anterior segment SOCT Anterius provides information of high clinical
value of subtle corneal dystrophies.In vivo measurement of epithelial thickness profile
and obervation of subtle corneal alterations in real time expand the applications of
SOCT for corneal imaging in both clinical and research settings
CR: A. Cervino, None; D. Bansal, Commercial Interest in Anterius SOCT, E; R.
Montes-Mico, None; J.J. Kaluzny, None.
Support: None
Purpose: The scleral spur is an important landmark that can be visualized cross
sectionally with ultrasound biomicroscopy or ASOCT. Identifying the location of the
scleral spur is required for many measurements of iridocorneal angle parameters,
including angle opening distance (AOD), trabecular iris space area (TISA) and
trabecular iris angle (TIA). Poor delineation of the scleral spur is a major cause of
angle measurement variability. We investigated the potential factors responsible for
scleral spur clarity in ASOCT.
Methods: We analyzed 42 eyes of 42 subjects. Thirty-two eyes had open and 7 had
narrow angles by dark room gonioscopy. ASOCT imaging was performed using a
horizontal and a vertical scan at a position bisecting the pupil. Three images were
captured in each orientation and the image with the best quality from each orientation
was selected for analysis. A single grader assessed the clarity of the scleral spur as 0
(no visibility), 1 (blurred ) and 2 (clear delineation of scleral spur) for each quadrant.
The total scleral spur delineation score (SSDS) was calculated by adding the individual
score from each quadrant. The association between age, sex, axial length, refraction
and the SSDS was evaluated with univariate and multivariate analyses.
Results: The mean (Â±SD) SSDS at the superior, nasal, inferior and temporal
quadrants were 1.76Â±0.43, 1.86Â±0.35, 1.05Â±0.70 and 1.90Â±0.30, respectively. The
inferior quadrant had the worst delineation of the scleral spur compared with the
others (p<0.001). No difference was found in the total SSDS between the open and
narrow angle groups (p=0.443). The total SSDS was significantly associated with
age (r=-0.483, p=0.001), axial length (r=0.421, p=0.006) and spherical error (-0.348,
p=0.024). Multivariate analysis showed that age and axial length are the 2 significant
independent predictors for scleral spur visibility.
Conclusions: The worst delineation of the scleral spur was found in the inferior angle,
in older subjects and in eyes with short axial length. As age and short axial length are
also risk factors for development of angle closure, further investigation is needed to
determine the clinical significance of scleral spur visibility.
CR: S.K. Dorairaj, None; J.J. Rousso, None; C.Y. Cheung, None; H. Li, None; R. Ritch,
None; C. Pang, None; D.S. Lam, Carl Ziess, F; C.K. Leung, Carl Ziess, F.
Support: Joseph Cohen Research Fund of NYGRI
2264 - D812
Thermal Imaging of the Ocular Surface and Adnexa
C. Purslow1, V. O’Connor2, M.P. Rubinstein2. 1School of Optometry & Vision Sciences,
Cardiff University, Cardiff, United Kingdom; 2Department of Ophthalmology,
Queen’s Medical Centre University Hospital, Nottingham, United Kingdom.
Purpose: To assess typical ocular thermal symmetry in a group of control subjects,
and to observe whether inter-ocular asymmetry in selected subjects appears related
to the presence of pathology of the ocular surface or adnexa.
Methods: A portable infra-red camera (ThermoVision A40M, Flir) was used to record
asymmetry in ocular and peri-orbital skin surface temperature in 49 healthy control
subjects (19M, 30F; mean age 41.3±18.2yrs), and in 22 symptomatic patients (14M,
8F; mean age 44.1±19.7yrs) attending a hospital emergency department. Statistical
comparisons using paired t-tests and confidence intervals were applied between
controls and groups of pathology, and cases of isolated pathology were also
observed.
Results: In control subjects, the mean temperature difference between corneae was
0.06±0.23°C (95% CI -0.005 to 0.13°C; p=0.07), and typical peri-orbital asymmetry was
0.09±0.19°C (95% CI 0.04 to 0.15°C; p<0.05). There was no significant thermal asymmetry
between symmetrical points on the face (0.05±0.42°C (95% CI -0.07 to 0.17°C; p=0.41).
The effect of age (0.07<p<0.52) and gender (0.29<p<0.94) on thermal asymmetry in
control subjects was statistically insignificant. Subjects with chalazia (n=10) showed
significant thermal asymmetry between eyelids: mean difference +0.54±0.33°C (95%
CI 0.19 to 0.88°C; p<0.05). Ocular surface temperature overlying corneal abrasions
(n=6) increased by +0.70±0.31°C (95% CI 0.37 to 1.02°C; p<0.005), whereas in cases
of acute corneal ulceration (n=3) average thermal difference between corneae was
-2.39±0.83°C (95% CI -4.45 to -0.32°C; p<0.05), with the affected eye exhibiting the
reduced temperature. Where an inflammation of the iris, sclera or conjunctiva was
present, the overlying increase in temperature varied from +1.52 to +3.66°C, compared
with the fellow eye in individuals (n=3).
Conclusion: Normal subjects exhibit insignificant thermal asymmetry, particularly
on the cornea. Inflammatory lesions involving the eyelids show a wide range of
increased temperature that probably relates to the degree of active inflammation at
presentation. With corneal lesions the degree of insult appears important: a traumatic
abrasion induces warm reflex tears, whereas ulceration disrupts the tear film readily
so that surface temperature appears cooler as a relatively cooler corneal surface is
exposed. Ocular thermography has the potential to be a useful, non-invasive tool to
examine inflammation of the ocular surface and adnexa.
CR: C. Purslow, None; V. O’Connor, None; M.P. Rubinstein, None.
Support: Nuffield Foundation
2261-2264
2265 - D813
Iris Recognition Technology in Newborns
H.C. Beck1A, I. Ezon1, L. Flom1A, C. Pitchford1B, L. Park1A. AOphthalmology, BObstetrics/
Gynecology, 1NYU Medical Center, New York City, NY.
Purpose: To create a database of iris images from 6 newborn and 100 adults iris images
to determine if newborn irides can be recognized with a Securimetric Pier 2.3 camera
under standard delivery room conditions.
Methods: Using a Securimetric Pier 2.3 camera, 100 adult iris images were collected by
instructing subjects to look forward with eyes open toward the handheld device. The
images of these adult eyes were to be used as comparators with 6 infant iris images,
also collected using the Securimetric Pier 2.3 camera. The infants’ irides were imaged at
birth and at 50 minutes post-partum, prior to application of ophthalmic erythromycin
ointment. The infant’s eyes were held open with gentle manual pressure, rather than
a speculum, while the image was taken. No personal health information of the adults
or the infants was collected; only an alphanumeric number was used to identify the
subjects. The imaging device, termed a “Personal Iris Imager” or PIA, contains a
miniature video camera that uses CCD (charge-coupled device) technology and a
low-level infrared illuminator. The illumination is centered at 750 nm, which is just
outside the visible spectrum. It has a numeric keypad for operator control and a small
LCD (liquid crystal display) screen that allows the operator to view the live video
image to facilitate focus and alignment of the iris image. A small PC-type processor
and hard drive inside the device are used to process and store the iris images. Images
are later downloaded to a desktop PC for analysis and archival storage.
Results: 100% of adult irides were successfully imaged and later recognized with the
Pier 2.3 camera. 0% of the infant irides were successfully imaged.
Conclusions: Although adult irides were easily imaged and recognized, infant irides
were not successfully captured using the Securimetric Pier 2.3 camera. Further study
using stillborn infant eyes might elucidate whether this failure of image capture is
due to the primitive structure of infant irides or the rapid eye movement and small
palpebral aperture of newborn infants. With this information, the technology can
be improved to easily image infant irides and use them as a unique identifier when
newborns are discharged from the hospital.
CR: H.C. Beck, None; I. Ezon, None; L. Flom, U.S. Patent 4,641,349, P; C. Pitchford,
None; L. Park, None.
Support: None
2266 - D814
Clinical Observations and Histopathological Findings of Mitomycin C
Topically Treated Cynomolgus Monkey Corneas
V. Bantseev1, G.P. Holley1, P.E. Miller2, R. Leedle1, J. Miller1, H.F. Edelhauser3,2, C.J.
Murphy2, B.J. Christian1, P.B. Smith1, T.T. Lam1. 1Toxicology, Covance Laboratories
Inc., Madison, WI; 2Comparative Ophthalmic Research Laboratories, Madison, WI;
3
Ophthalmology, Emory University, Atlanta, GA.
Purpose: To describe the clinical observations and histopathological changes following
topical 0.2 % Mitomycin C (MMC) treatment in the cynomolgus monkey cornea.
Methods: The central cornea of 10 anesthetized Cynomolgus monkeys received a single
topical dose for 2 min as follows: Group 1 (n=5), bilateral 0.9% saline, right cornea
debrided with contralateral eye as nondebrided control; Group 2 (washed with BSS
after dosing, n=5) bilateral 0.2% MMC, right cornea debrided with contralateral eye
as control. Hand-held slit lamp biomicroscopy and indirect ophthalmoscopy were
carried out at baseline and on Day 14 following dosing. Animals were euthanized on
Day 15 and central corneas were removed and processed for hematoxylin and Eosin
(H&E) and periodic acid schiff’s (PAS) staining.
Results: Ophthalmic exams of Group 1 on Day 14 showed re-epithelialization (Group 2
also) and slight corneal haze and subtle corneal epithelial pigmentation in 4/5 debrided
eyes dosed with 0.9% saline with no findings in control eyes. In contrast, 4/5 debrided
eyes dosed with 0.2% MMC (Group 2) showed subtle corneal edema with all 5 having
diffuse pigmentation of the anterior cornea. The contralateral, nondebrided MMC
control eyes lacked these findings. Histopathology showed a lack of abnormal findings
in nondebrided/saline and debrided/saline controls. In Group 2, the nondebrided/
MMC control corneas showed flattened epi and endothelium in 3/5 corneas similar
to debrided/MMC treated eyes. However, the epi changes in the nondebrided/MMC
treated eyes were less severe compared to those of the debrided/MMC treated eyes.
In addition, in the debrided/MMC corneas, pigment in basal and intermediate epi,
inflammatory cells at the periphery of the cornea and decreased endothelial nuclei were
noted in all 5 corneas. PAS staining confirmed the peripheral location of the pigment
in the epi and showed intact basement membranes of similar thickness.
Conclusions: Clinical observations were confirmed by histopathology, which also
revealed the presence of inflammatory cells in these corneas. In addition, histopathology
noted some degree of epi and endothelial defects in nondebried/MMC treated corneas.
While clinical observations cautioned the possible defects induced by exposure to
MMC with a compromised epithelium, histopathology demonstrated a possible
deleterious effect of exposure to MMC without a compromised epithelium.
CR: V. Bantseev, None; G.P. Holley, None; P.E. Miller, None; R. Leedle, None; J.
Miller, None; H.F. Edelhauser, None; C.J. Murphy, None; B.J. Christian, None; P.B.
Smith, None; T.T. Lam, None.
Support: None
2265-2266
Tuesday, April 29, 8:30 AM - 10:15 AM Room 305 Paper Session Program Number Range: 2420-2426
305. Depth-of-Focus and IOL Optical Performance Organizing Section: VI
2420 - 8:30AM
Depth of Focus for Different Aberration Patterns Using an Adaptive-Optics
Vision Simulator
2421 - 8:45AM
High Order Aberrations Effect on the Eye’s Depth of Focus Evaluated by Using
an Adaptive Optics Visual Simulator
P.A. Piers1, S. Manzanera2, H. Weeber1, A. Mira2, C. Canovas2, P. Artal2. 1Applied
Research, AMO Groningen, Groningen, The Netherlands; 2Laboratorio de Optica,
Universidad de Murcia, Murcia, Spain.
K.M. Rocha1,2, L. Vabre3, N. Chateau 3, J. Ramos-Esteban1, R.R. Krueger1. 1Refractive
Surgery-Cole Eye Inst, Cleveland Clinic Foundation, Cleveland, OH; 2UNIFESPEPM, Sao Paulo, Brazil; 3Imagine Eyes, Orsay, France.
Purpose: To use an adaptive optics vision simulator (AOVS) to explore the impact of
different aberration patterns on subjective depth of focus (DOF) determined using
through-focus reading acuity. These tests will also be used to examine the suitability
of optical metrics for predicting subjective DOF.
Methods: An AOVS was constructed that allows us to simultaneously manipulate the
effective ocular wavefront aberration and measure the resulting visual performance
through different object vergences. Simulator testing was performed in white light on
3 subjects with a 4.8 mm pupil and paralyzed accommodation. DOF was determined in
each subject for 6 cases of aberration: 1) the subject’s natural aberration pattern; 2) all
aberrations corrected; 3) positive spherical aberration of 0.22 μm, 4) negative spherical
aberration of 0.22 μm; 5) vertical coma of 0.22μm; and 6) astigmatism at 45° of 0.22μm.
Reading acuity was determined for each of the 6 cases at best focus. Subsequently,
subjective DOF was evaluated for these cases by determining the positive and negative
defocus range for which the subject had acceptable reading acuity for a letter size
twice that of their peak acuity. The ocular wavefront aberration was recorded at each
focus position and used to determine MTF for corresponding spatial frequencies as
well as MTF volume and encircled energy, thus enabling a comparison of objective
DOF and subjective DOF.
Results: Correcting all of the monochromatic aberrations of the eye decreased DOF.
Differences in DOF were measured for the 4 different cases with similar RMS values. A
comparison of optical DOF and subjective DOF showed similar trends for the 6 cases,
but MTF volume is not a strong predictor of subjectively determined DOF using reading
acuity. MTF values at the selected letter sizes are better optical predictors of DOF.
Conclusions: Using an AOVS it was determined that inducing different types of
higher-order aberration patterns results in different measured values of subjectively
measured DOF. An AOVS is a powerful tool that can be used to investigate the optical
factors that contribute to subjective DOF.
CR: P.A. Piers, Advanced Medical Optics, E; S. Manzanera, Advanced Medical
Optics, C; H. Weeber, Advanced Medical Optics, E; A. Mira, Advanced Medical Optics,
C; C. Canovas, Advanced Medical Optics, C; P. Artal, Advanced Medical Optics, C.
Support: MEC_FIS2004-2153 (Spain)
Purpose: To evaluate the impact of applying individual Zernike coefficients (spherical
aberration, coma and trefoil) on depth of focus.
Methods: The ocular aberrations of 10 normal subjects were measured up to the 10th
Zernike order using a crx1 Adaptive Optics Visual Simulator (Imagine Eyes, France)
based on a Shack-Hartmann wavefront sensor and an electromagnetic deformable
mirror functioning with a closed-loop feedback algorithm throughout the experiment
to control the wavefront shape. Subjects’ eyes were dilated with 1% Tropicamide to
inhibit accommodation and the accommodative response was checked using the
same device 15 minutes after the drops were inserted. The crx1 was used to introduce
varying degrees of pure Zernike aberrations, including coma (Z(3,-1)), trefoil (Z(3,-3))
at magnitudes of +/-0.3 and spherical aberrations (Z(4,0)) at magnitudes of +/-0.3,+/-0.6
and +/-0.9µm through a fixed 6-mm pupil diameter. Depth of focus curves were plotted
for each simulated aberration using measurements obtained by displaying 10 Sloan
letter optotypes. Each subject’s depth of focus was assessed by plotting the number
of read letters as a function of the induced defocus.
Results: The obtained results show that applying pure spherical aberration coefficients
linearly shifts the best point of focus by 1.3 D for each 0.5µm of spherical aberration in
the direction of its sign. Simulating spherical aberration equally increased the depth
of focus value up to 2D, depending on the sign and the value of its coefficient. This
increase reached a maximum before decreasing in the presence of strong spherical
aberration values (0.9µm). Trefoil and coma did not appear to shift the best focus point
and only slightly changed the depth of focus value.
Conclusions: By using adaptive optics based technology for vision simulation, we
were able to draw quantitative results on the effects of higher-order aberrations
on the depth of focus. Simulating both positive and negative spherical aberrations
significantly improved subjects’ Visual Depth of Focus (VDoF) when compared to the
effects on VDoF observed when introducing coma and trefoil. Spherical aberrations
equally appear to increase subjects’ best focus point. Our results suggest that spherical
aberration should be further studied and incorporated into the design of optical
corrections for presbyopia. This has the clinical potential for both in-office patient
simulations and for the implementation of adaptive optics into refractive surgery
techniques.
CR: K.M. Rocha, None; L. Vabre, E, E; P, P; N. Chateau, P, P; J. Ramos-Esteban,
None; R.R. Krueger, None.
Support: None
2422 - 9:00AM
Interaction Between Primary and Secondary Spherical Aberrations and Its
Impact on Retinal Image Quality Through Focus
2423 - 9:15AM
Longitudinal Chromatic Aberration in Eyes Implanted With Acrylic Itraocular
Lenses
L.J. Nagy1A,1B, G. Yoon1B,1A. ABiomedical Engineering, BOphthalmology, 1University of
Rochester, Rochester, NY.
H.S. Ginis1, D. Kaltsa1, D. Siedlecki2, I. Pallikaris1. 1Institute of Vision and Optics,
University of Crete, Heraklion, Greece; 2Institute of Physics / Imaging Optics
Group, Wroclaw University of Technology, Wroclaw, Poland.
Purpose: It has been proposed that spherical aberrations (SA) can improve retinal
image quality for a greater depth of focus with a single optical element. This study
was performed to understand how primary and secondary SA can affect the resultant
retinal image quality (RIQ) through focus.
Methods: Primary (Z40) and secondary (Z60) SA were modeled using a custom made
algorithm in Matlab. The aberration interaction was calculated for a 4.5mm pupil in
monochromatic light (0.632μm) from 0 to 3 diopters (D). The area under the visual
Strehl optical transfer function (AVSOTF) was calculated to predict visual performance
as a function of focal ranges (distance = 0 to 0.75D, intermediate = 1 to 1.75D and near
= 2 to 3D). In this model, interactions were optimized for distance RIQ which was
chosen as the maximum VSOTF value for each interaction.
Results: With primary SA alone, intermediate and near RIQ began to dominate the
AVSOTF at -0.2μm and -0.4 μm respectively with diminished distance RIQ at these
points. On the contrary, both positive and negative values of secondary SA produced
optimal intermediate and near RIQ. There was a strong positive correlation between
primary SA and positive secondary SA (R 2 >0.97) when they interact with each other.
The ratios of secondary SA to primary SA for the intermediate and near peaks were
0.35 ± 0.01. The difference in secondary SA between the intermediate and near peaks
was constant (0.1 ± 0.01 μm). The equivalent RIQ for intermediate and near focal ranges
was obtained at half the secondary SA difference between the peaks.
Conclusion: The AVSOTF can be a useful tool to determine appropriate amounts of
spherical aberrations to optimize performance of multifocal lenses. The dominance
of RIQ at different object distances can be manipulated with interactions of primary
and secondary SA.
CR: L.J. Nagy, None; G. Yoon, Bausch & Lomb, F; Bausch & Lomb, C.
Support: NIH/NEI grant R01EY014999, Research to Prevent Blindness
Purpose: It has been reported that acrylic Intraocular lenses (IOLs) are characterized by
increased longitudinal chromatic aberration (LCA) in respect to the natural crystalline
lens. It was the purpose of this study to employ a method based on subjective refraction to
measure LCA in a series of cataract patients implanted with monofocal acrylic IOLs.
Methods: A Badal optometer with interchangeable narrow-band (5nm FWHM)
optical filters and broadband (incandescent lamp) target illumination was developed.
A rail system enabled the axial displacement of the target and the measurement of
its position. The target consisted of a vertical orientation grating involving various
spatial frequencies ranging from 3 to 30 cycles/degree. Fourteen patients (sixteen
eyes) implanted with acrylic IOLs (Lenstec Inc, St. Petersburg, FL) with dioptric
powers ranging from 17 to 23.5 D and ten normal subjects (ten eyes) were enrolled in
the study. All subjects had best spectacle corrected visual acuity higher or equal to
0.8. The subjects (corrected with trial lenses for sphere and cylinder) were instructed
to focus the target by maximizing the number of visible grating lines. This ensured
that in a simple criterion of subjective best focus was employed throughout the
measurements. The task was repeated ten times for each wavelength and the
corresponding positions of the target were recorded. The additional refraction of
each patient was evaluated -using the above mentioned method- for seven different
wavelengths ranging from 490 to 630 nm. Ten normal subjects under cycloplegia
underwent the same measurements in order to validate the method. The study was
conducted under Institutional board approval. An informed consent was obtained
from each subject prior to the measurement.
Results: The chromatic focal shift for the normal subjects as determined with the
present method was 0.905 D (SD=0.24) between 490 and 630 nm, similar to the
corresponding mean value reported in the literature (0.85D). The pseudophakic eyes
exhibited a markedly higher chromatic focal shift (1.58 ± 0.52 D). Various polychromatic
image quality metrics were calculated and retinal image quality was simulated.
Conclusions: Our results demonstrate that pseudophakic eyes implanted with acrylic
IOLs have increased LCA in respect to intact eyes. Alternative IOL materials and
designs with reduced LCA may provide better polychromatic retinal image quality. The
corresponding visual benefit for cataract patients needs to be further investigated.
CR: H.S. Ginis, None; D. Kaltsa, None; D. Siedlecki, None; I. Pallikaris, None.
Support: None
2420-2423
Tuesday, April 29, 8:30 AM - 10:15 AM Room 305 Paper Session Program Number Range: 2420-2426
305. Depth-of-Focus and IOL Optical Performance Organizing Section: VI
2424 - 9:30AM
Polychromatic Image Quality in Pseudophakic Model Eyes With Hybrid
Diffractive Multi-Focal Intra-Ocular Lenses
2425 - 9:45AM
Improvement in Optical Image Quality by Custom Selection of Aspherical Iol
L. Wang, D.D. Koch. Department of Ophthalmology, Baylor College of Medicine,
Houston, TX.
S. Ravikumar, A. Bradley, L.N. Thibos. School Optometry, Indiana University,
Bloomington, IN.
Purpose: Hybrid intra-ocular lenses with refractive and diffractive components have
been developed for multi-focal ophthalmic use. Although the lens design generally
involves one wavelength (550nm), pseudophakic patients live in a polychromatic
environment. The polychromatic performance of these hybrid lenses depends on the
interaction of the negative chromatic aberration (CA) of the diffractive component with
the positive chromatic aberration of the cornea and the refractive component of the IOL.
We have evaluated polychromatic image quality in a virtual pseudophakic eye (based
on Indiana Eye) with hybrid diffractive/refractive intra-ocular lens implants.
Methods: Pupil plane wavefront maps were developed based upon diffractive lens
designs and eye optical characteristics. Polychromatic point-spread functions were
calculated by summing monochromatic PSFs at 10 nm intervals across the visible
spectrum. Image quality was assessed for a range of pupil sizes and target vergences
from +3 to -5 D (working distance range beyond infinity to 20 cm).
Results: The polychromatic IQ metric “Light in the bucket” demonstrates that, with
a 3.75 mm pupil diameter, the diffractive lens alone can suffer from a 25% decrease
in polychromatic IQ at near focus compared to design wavelength (due to diffractive
CA). However in the model pseudophakic eye, polychromatic retinal IQ at near focus is
almost identical to monochromatic IQ at the design wavelength because the diffractive
lens CA almost cancels the refractive CA of the IOL and cornea. Unlike the near image,
polychromatic distance IQ does not benefit from CA canceling effect of the diffractive
element. These results are highly dependent upon pupil size, specific lens design and
the levels of monochromatic aberrations present in the pseudophakic eye.
Conclusions: Inclusion of a hybrid IOL with approximately +3D of add power
essentially achromatizes the near image. Also, polychromatic analysis is essential to
obtain the desired near/distance balance in retinal image quality.
CR: S. Ravikumar, Graduate Stipend partially supported by grant from Alcon
Research Labs, F; A. Bradley, Consultant to Alcon Research Labs, F; L.N. Thibos,
None.
Support: NIH RO1 EY005109 and Alcon Research Labs
Purpose: In a previous study, we found that the amount of IOL spherical aberration
(SA) producing best image quality varied widely among subjects and could be
predicted based on the full spectrum of anterior corneal higher-order aberrations.
The purpose of this study is to evaluate the improvement in optical image quality by
custom selection of an aspherical IOL.
Methods: In 65 eyes of 43 patients with ages 40 to 80 years, simulated implantation of
5 IOLs in each eye was performed: 1) customized aspherical IOL with the optimized
IOL SA predicted using the formulas developed in previous study (Optimized IOL),
2) Tecnis IOL (SA = -0.27 µm), 3) AcrySof IQ (SA = -0.20 µm), 4) SofPort AO (SA = 0.00
µm), and 5) traditional spherical IOL (SA=+0.18 µm). Simulations were performed for
perfect IOL centration and horizontal decentration of 0.25 mm and 0.50 mm. Using the
ZernikeTool program (AMO), the polychromatic modulation transfer function (PMTF)
and the PMTF volumes up to 15 and 30 cycle/degree with Stiles-Crawford effect were
calculated to assess the optical image quality (6- and 4-mm pupils). Repeated analysis
of variance and Bonferroni correction were used.
Results: For a 6-mm pupil, the Optimized IOL produced higher PMTF values with
decentration up to 0.25 mm; with decentration of 0.50 mm, values with Optimized IOL,
Tecnis and IQ were better than those with AO and standard IOL. For a 4-mm pupil,
optical image qualities with the Optimized IOL, Tecnis and IQ were significantly better
than those with AO and standard IOL with decentration up to 0.25 mm.
Conclusions: Our results demonstrated that, with 6-mm pupils, a customized
aspherical IOL based on anterior cornea HOAs significantly improved optical image
qualities with decentration up to 0.25 mm. The optimized IOL and IOLs with negative
SA provided better optical quality than AO and standard IOLs with decentration up
to 0.5 mm for 6-mm pupils and with decentration up to 0.25 mm for 4-mm pupils.
CR: L. Wang, None; D.D. Koch, None.
Support: unrestricted grant from Research to Prevent Blindness, New York, NY
2426 - 10:00AM
Two Methods for Measuring Light Scatter in Intraocular Lenses
M. van der Mooren1, J. Coppens2, T. van den Berg2, P. Piers1. 1Applied research,
AMO Groningen BV, Groningen, The Netherlands; 2Netherlands Institute for
Neuroscience, Amsterdam, The Netherlands.
Purpose: Light scatter in intraocular lenses may be a significant factor in quality
of vision for patients implanted with these lenses. The purpose of this study was
to develop two complementary quantitative methods for measuring light scatter in
intraocular lenses. The measured amount of light scatter found in healthy crystalline
lenses can be used as a basis for comparison.
Methods: Using Method 1, light was projected onto the intraocular lens (IOL) to
determine the angular dependent light scatter. The IOL models were measured in
a liquid cell. The IOL was first illuminated fully and then with a very narrow slit.
Under slit illumination the scattered light was measured so that the bulk and surface
scatter could be separated for large angles.
Method 2 measures the light intensity distribution of an IOL in an eye model
representing average chromatic and spherical aberration. The average cornea eye (ACE)
model consists of a liquid cell and a cornea with spherical and chromatic aberration
similar to the average human eye. Various wavelengths and pupil sizes were used
while measuring the light intensity distribution of the IOL models.
Results: With Method 1 the light scatter was measured in several directions for both
full and slit illuminations for angles larger than 3 degrees. Light scatter originated
from the surface and/or the bulk of the lens, for example in the presence of micro
vacuoles. Depending on the number and size of the micro-vacuoles, models of such
lenses showed significant light scatter levels compared to a healthy crystalline lens.
For Method 2, intensity profiles were stitched together to obtain a dynamic range
of 6 log units and an angular field of approximately 3 degrees. Measurements of
multifocal and monofocal IOLs with different pupil sizes enabled us to compare the
pupil area ratio with the corresponding light power ratio. The measured multifocal
lenses showed unequal ratios, indicating that all incoming light will not focus to
the central field.
Conclusions: The two methods for measuring light scatter are complementary in the
angular domain. The data they provide can form a basis for comparison with data
from a healthy crystalline lens. It can be concluded that both methods are valuable
for further improving quality and performance when designing IOLs.
CR: M. van der Mooren, Advanced Medical Optics, E; J. Coppens, Advanced
Medical Optics, F; T. van den Berg, Adcanced Medical Optics, F; P. Piers, Advanced
Medical Optics, E.
Support: IS062031
2424-2426
Tuesday, April 29, 8:30 AM - 10:15 AM Hall B/C Poster Session Program Number/Board # Range: 2534-2546 / A77-A89
322. Spatial, Temporal and Binocular Vision Organizing Section: VI
2534 - A77
Evaluation of a Modified Siemens Star for Accurate Measuring of Contrast
Sensitivity
2535 - A78
Spatial and Temporal Luminance Contrast Sensitivity Measurements Using
Psychophysical Tests Developed for Personal Computers
H. Jungnickel1, K. Strohm1, M. Gebhardt1, H.-J. Grein2. 1Course of Optometry,
University of Applied Sciences, Jena, Germany; 2Course of Optometry, University
of Applied Sciences, Luebeck, Germany.
C.C. Teixeira, A.R. Rodrigues, L.C.L. Silveira. Physiology, Universidade Federal do
Para, Belem, Brazil.
Purpose: To enable subjective measuring of the relative low visual improvements
through higher order aberrations correction, particularly sensitive and accurate visual
tests are essential. Conventional contrast sensitivity tests on charts are unsuitable
for that purpose. Up to now Siemens stars are used to check optical systems. Aim
of the study was to develop a new contrast test using a sinusoidal Siemens star as
test pattern.
Methods: Test patterns (programmed with Flash, Adobe Systems) were presented on
a standard 15” TFT display. Peripheral parts of the pattern (= low spatial frequencies)
can be resolved whereas central parts (= high spatial frequencies) are seen as a
uniformly grey area. Subjects interactively change the size of a black circle almost
stepless via PC keyboard to mark the threshold of resolution. In a pilot study with
10 subjects measurements with 5 different contrasts (20%, 10%, 5%, 2.5% and 1.25%)
were performed with 10 repeats for each contrast. Siemens star either was stagnant
or rotated with 10 degrees per second to prevent local adaptation. The Flash program
calculated mean detectable spatial frequency in each case. Test distance was 6 meters
(20 feet), one eye was occluded.
Results: On average the adjusted spatial frequencies were 37.1 cycles per degree (at
a contrast of 20%), 31.6 cpd (10%), 26.2 cpd (5%), 21.1 cpd (2.5%) and 15.9 cpd (1.25%).
No significant differences between stagnant and rotating Siemens stars were found.
Standard deviations for sets of 10 repeats rise with decrease of contrast and average
between ±12.4% and ±26.2%. Reducing repeats down to 5 also produces precise
results.
Conclusions: The modified Siemens star seems to be an adequate test for quick and
accurate determination of contrast sensitivity. Low standard deviations show a good
applicability to verify improvements of correcting higher order aberrations.
Purpose: The aim of this work is to measure both spatial and temporal luminance
contrast sensitivity using psychophysical tests developed for personal computers and
to obtain statistical norms for normal young subjects.
Methods: We used a Pentium IV microcomputer (1.7 GHz, 512 MB RAM, 40 GB hard
disk) and a software written with C++ Builder 3.0. Visual stimuli were generated using
an Annihilator 2 graphic card (Creative) with 24 bits color pallet (8 bits / gun) and
displayed on a Multiscan G420 CRTl (Sony), 19”, 1024 x 768 pixels spatial resolution,
and 120 Hz frame rate. The luminance output as a function of CRT input voltage was
linearized by software. Luminance measurements were performed using Chroma
Meter CS-100A colorimeter (Konica Minolta), 1o aperture, placed at 1 m from the
monitor. A dithering routine was used to obtain 10 bits gray levels. We measured
the luminance spatial contrast sensitivity of 30 subjects (15 men, 16-30 years old) and
the luminance temporal contrast sensitivity of 34 subjects (16 men, 16-30 years old).
Spatial contrast sensitivity was evaluated using sinusoidal black-and-white gratings
of eleven spatial frequencies, 0,2, 0,5, 0,8, 1, 2, 4, 8, 10, 15, 20, and 30 cycles per degree
(cpd). Temporal contrast sensitivity was measured using a flickering square field at
seven frequencies, 0,5, 1, 2, 4, 8, 16, and 32 Hertz (Hz). Mean luminance was kept at
42 cd/m 2 for all stimulus conditions. Subjects were monocularly tested at 3 m from
the CRT monitor.
Results: Spatial contrast sensitivity curves had the expected band-pass shape, peaking
at 300 in the 2-4 cpd range and having a spatial frequency cut-off at 30-40 cpd. Temporal
contrast sensitivity curve had a low-pass shape, peaking at 100 in 8 Hz. Statistical
tolerance and confidence intervals were calculated for both data set.
Conclusions: These results suggest that psychophysical tests developed for low cost
personal computers can be useful to measure spatial and temporal contrast sensitivities
of normal subjects and has potential applications on clinical evaluations.
CR: C.C. Teixeira, None; A.R. Rodrigues, None; L.C.L. Silveira, None.
Support: CAPES, CNPq, FUNTEC, and FINEP-IBN Net.
CR: H. Jungnickel, None; K. Strohm, None; M. Gebhardt, None; H. Grein, None.
Support: None
2536 - A79
Direct Comparison of New Clinical Tests of Resolution and Recognition of
Spatial Contrast Sensitivity in Younger and Older Adults
2537 - A80
Uniformity of Measuring Visual Acuity in Published Studies
R.J. Adams1A, C.G.M. Bishop1B, A.L. Barrett1B, A.M. Surprenant1B, M.L. Courage1A.
A
Psychology & Pediatrics, Faculties of Science & Medicine, BPsychology, 1Memorial
University, St John’s, NL, Canada.
Purpose: Over the past few years, new clinically-oriented tests have emerged for
measuring spatial contrast sensitivity (CS), arguably the most comprehensive single
measure of human vision. Assessment of CS has become particularly important in
aiding neuro-ophthalmic diagnoses, and in the pre- and post-surgical evaluation of
patients undergoing refractive surgery. However, despite the variety of CS tests and
their widespread use in clinical practice, tests are often used interchangeably, and
have yet to be compared in any systematic manner. Here we provide these essential
data across a broad age range.
Methods: Within a single session, 30 young adults (M = 23 yr) and 33 seniors (M =
72 yr) were assessed monocularly with sine-wave grating tests of resolution CS [3m
FACT chart (Stereo Optical) and the 60 cm Adams CS booklet], and recognition CS
[Rabin CS and the Sloan low contrast CS tests (both Precision Vision)]. To provide a
fuller spectrum contrast sensitivity function (CSF), Rabin and Sloan CS tests were
assessed at 1, 2, and 3 m. For comparison and validation, we also measured Snellen
and Landolt acuity. For all tests, luminance was held constant at 70 cm/m2.
Results: Correlations among tests were significant (r = 0.44 to 0 .84, p< 0.01) with the
exception of seniors tested with the CS booklet and young adults tested with Sloan
CS vs. FACT. Coefficient of reliability analyses also confirmed that there was excellent
agreement among tests. In particular, the Rabin CS test appeared to have the best
prediction among the different measures of spatial vision.
Conclusions: Given the diversity of CS tests, the consistency is impressive especially
given that most tests were also able to predict maximal spatial resolution. This suggests
that current tests are effective and comparable measures of spatial contrast sensitivity,
and thus, should have good clinical utility. The shortcoming of the CS booklet among
seniors is likely explained by variations in near-accommodation associated with
presbyopia.
CR: R.J. Adams, None; C.G.M. Bishop, None; A.L. Barrett, None; A.M. Surprenant,
None; M.L. Courage, None.
Support: Natural Sciences & Engineering Research Council of Canada / Janeway
Hospital Research Advisory Foundation/ NIH/NIA
M.A. Williams1, T.N. Moutray2, A.J. Jackson2. 1Ophthalmology, Queens University of
Belfast, Belfast, United Kingdom; 2Ophthalmology, Royal Victoria Hospital, Belfast,
United Kingdom.
Purpose: To investigate methods used in contemporary ophthalmic literature to
designate visual acuity (VA).
Methods: Papers in all 2005 editions of five ophthalmic journals were considered.
Papers were included if VA or vision was mentioned in the abstract and if the study
related to age-related macular degeneration, cataract or refractive surgery. If a paper
was selected on the basis of its abstract, the full text of the paper was examined for
details on types of chart used to measure VA, means of expressing VA in results and
specifics concerning chart features, testing protocols and data analysis.
Results: One hundred and thirty-two papers were included. The most common means
of referring to VA measurement in methods sections was merely as “Best Corrected
Visual Acuity” (34.8%; n=46/132). When chart type was mentioned, the most commonly
specified charts were LogMAR acuity (32.6%; n=43/132) and Snellen (24.2%, n=32/132).
The commonest ways in which acuity measurements were presented in the results
sections were as Snellen fractional (47.0%; n=62/132) and LogMAR (22.0%;n=29/132).
Most papers gave no details regarding chart features, testing protocols or data analysis.
Twenty-one studies stated that VA data was transformed into another notation to
facilitate statistical analysis.
Conclusions: Substantial diversity exists in the information given regarding the
measurement of VA, and in the means by which VA is measured, analysed and
expressed. Sufficient detail should be given on VA measurement to enable others to
duplicate the research. We suggest that LogMAR-based charts should always be used
to measure vision in prospective studies and their use encouraged in clinical settings.
Transforming VA data for results and analysis is hazardous.
CR: M.A. Williams, None; T.N. Moutray, None; A.J. Jackson, None.
Support: None
2534-2537
2538 - A81
Accuracy of the Heine Lambda 100 Retinometer
2539 - A82
Measuring Differential Visual Latency With a Simultaneity Paradigm
F.W. Chang, M. Eller, S.B. Steinman, P. Gunvant. Southern College of Optometry,
Memphis, TN.
S. Patel1, H. Leung1, S.H. Schwartz1, W.H. Swanson2. 1Vision Sciences, SUNY
Optometry, New York, NY; 2School of Optometry, Indiana University,
Bloomington, IN.
Purpose: Patients undergoing retinometer testing before cataract surgery can show
lower acuity than Snellen acuity. We investigated causative factors by comparing acuity
for projected Snellen letters, the Heine Lambda 100 retinometer, and red-black gratings
on a computer screen. Methods: Snellen acuity was measured by standard clinical
techniques. Equivalent psychophysical procedures were used for retinometer and
computer acuity measurements (n=58). The orientations of the grating bar orientations
were randomized at each acuity level. Computer-based gratings subtended visual
angles close to those of the retinometer gratings. Acuity was recorded as the last bar
width in which the subject could correctly identify at least 3 of 5 grating orientations,
i.e., > 60% correct detection. In a further experiment (n=30), both grating orientation
and bar width were randomly selected on each presentation and a psychometric
function was generated. Results: All subjects were ≥ 20/20 as measured by the Snellen
letters and computer-generated gratings. A statistically significant number of subjects
had lower retinometer acuities. Correct detection remained close to 100%, decreasing
for < 20/25 stimuli, but only dropping to 91% for 20/25 stimuli. Conclusions: The
lower visual acuity measured with the retinometer is not attributable to differences
in criterion level. Observers were encouraged to guess, forcing them to set a uniform
criterion level. The same threshold % correct was used on both retinometer and
computer grating acuity. If the smallest retinometer bars were really smaller than
20/25, % correct would decrease with a high slope for that bar width alone, but %
correct decreased prior to the 20/25 stimulus. If all gratings had a smaller width or
decreased contrast, % correct would fall below 100% for bar widths much larger than
20/25, yet % correct detection only dropped to 91% for 20/25 stimuli. A threshold near
20/20 would result if smaller bar sizes were present in the retinometer. Lower acuities
on the retinometer can therefore be attributed to the lack of a 20/20 target. The acuity
values obtained by the retinometer are acceptable because the acuity would remain
a conservative estimate of post-operative vision.
CR: F.W. Chang, None; M. Eller, None; S.B. Steinman, None; P. Gunvant, None.
Support: None
Purpose: To obtain reference norms that can be used to study function in the diseased
eye, we (1) determined the symmetry of superior and inferior visual latency for brief
flashes presented in the nasal visual field of healthy eyes and (2) ascertained the
within and between session stability of these measurements.
Methods: A pair of vertically aligned squares (0.43 º each; 66 cd/m 2 on a 6 cd/m 2
background)), centered on the horizontal meridian and separated by 10 or 15 º, was
flashed for 100 msec at various temporal asynchronies. The subject’s task was to
indicate whether the top or bottom square appeared first, or whether they appeared
simultaneously (or not sure). Interleaved staircases were employed to determine
the boundaries of the simultaneity range. The initial asynchrony was 250 msec. Ten
reversals were obtained for each staircase, and the final 8 were averaged to arrive at a
boundary. To assess validity, data were fit with a Weibull function. The midpoint of the
simultaneity range was taken as the latency difference between superior and inferior
field (differential latency or DL). A DL of zero would indicate perfect symmetry.
Twenty-two subjects participated in the study (range: 21 -79 yrs of age; mean 40 yrs).
In a session, DL was determined both 5 and 15 º nasally using inter-trial step sizes
of 20 and 40 msec (for a total of 4 conditions). During each session, 2 measures of DL
were obtained for each of the 4 conditions. Two sessions, separated by at least a week,
were conducted for each subject.
Results: The average DL across all sessions/conditions (typically 16 measurements
per subject) ranged from -15 (superior field faster) to +5 msec, with a mean value of
-4 +/-6. The average width of the simultaneity range was 136 +/- 59 msec, and ranged
from 35 to 270 msec. Neither retinal location (p = 0.912) nor the inter-trial step size
(p = 0.442) significantly affected DL (within-subjects ANOVA). Within session DL
variability ranged from 1 to 15 msec per subject with a mean of 9 +/-4, while between
session DL variability ranged from 1 to 22 msec with a mean of 7 +/-4. Neither within
nor between session DL variability were affected by retinal location (p = 0.767 and
0.331, respectively) or inter-trial step size (p = 0.440 and 0.267).
Conclusions: DL is similar across subjects, revealing little vertical asymmetry and
minimal variability for the retinal loci and inter-trial step sizes that were tested.
Both within and between session reliability were strong. These data suggest DL as a
potential methodology to directly compare latencies of superior and inferior retinal
loci in the diseased eye.
CR: S. Patel, None; H. Leung, None; S.H. Schwartz, None; W.H. Swanson, None.
Support: Vision Service Plan
2540 - A83
Effects of Pulsed and Continuous Glare on Obstacle Avoidance
2541 - A84
Effects of Ethyl Alcohol on Visual Function
P.A. Smith1, T.K. Kuyk1, J.R. Dykes1, L.N. McLin2, L.E. Barnes2. 1Warfighter Concepts
and Applications, Northrop Grumman, San Antonio, TX; 2Human Effectiveness
Directorate, Air Force Research Laboratory, San Antonio, TX.
A. Weber, N. Plange, C. Rennings, M. Kaup, J. Huth, P. Wolter, G. Roessler, T. Kirschkamp,
A. Remky. Ophthalmology Department, University Hospital Aachen, Aachen,
Germany.
Purpose: In some situations, pulsed or strobed light has been found to impair
performance more than steady light. Furthermore, a flickering light at a frequency
around 10 Hz can appear brighter than a steady light in a phenomenon known as
brightness enhancement. The goal of this study was to determine if pulsed glare (PG)
had a greater effect than continuous glare (CG) on human performance in an obstacle
avoidance task that requires visual processing of moving stimuli. A second objective
was to assess if there was any evidence of brightness enhancement.
Methods: The ability to avoid obstacles in a simulated driving task was assessed in
eight subjects under twilight (3 cd·m-²) lighting conditions. The task was maneuvering
through a slalom course of rows of warning cones at 10 and 25 mph under normal
viewing or with different levels of glare present. The glare source was a 532 nm green
laser centered in the display field of view and operated at corneal irradiances of 6, 19,
60, 190 and 600 µW·cm-². The laser was either on continuously or pulsed at 8 or 12 Hz
with a .317 duty cycle to give average irradiances of 1.9, 6, 19, 60, and 190 µW·cm-². The
dependent variable was the probability of hitting cones, with an adjustment made
for accidentally going off road and around the cones.
Results: Performance declined as glare intensity increased in both the PG and CG
conditions, with the first significant increase in probability of cones hit occurring at
60 µW·cm-² and rising to 40 and 30%, respectively, at 600 µW·cm-². Additional analysis
indicated there was no difference between the 8 and 12 Hz PG conditions, so the
results were combined. When the two glare types were compared with respect to
peak irradiance level, PG was about 50% less effective from 60 to 600 µW·cm-² than
CG in reducing performance. However, when CG and PG were compared with respect
to average irradiance, PG was about 50% more effective than the CG (F = 6.489; p =
.038) in reducing performance.
Conclusions: Both CG and PG were effective in disrupting human performance in
an obstacle avoidance task at irradiance levels of 60 µW·cm-² and above. The relative
effectiveness of the two glare types depends on how they are compared with respect
to irradiance. When compared with respect to average irradiance, the PG was more
effective than CG. This suggests that brightness enhancement may have occurred.
CR: P.A. Smith, None; T.K. Kuyk, None; J.R. Dykes, None; L.N. McLin, None; L.E.
Barnes, None.
Support: USAF Contract F4162402D7003
Purpose: To test the effect of ethyl alcohol on visual function in normal subjects.
Methods: In 12 normal subjects (age: 27-43 yr; 4 male, 8 female), Frequency Doubling
Perimetry (FDT) and Short-wavelength Automated Perimetry (SWAP) was performed
before and 60 min after oral intake of 80 ml 40 vol% ethyl alcohol. Mean deviation (MD)
and pattern standard deviation (PSD) were evaluated. Additionally, systemic blood
pressure, heart beat, intraocular pressure (IOP), and blood alcohol concentration were
assessed. Statistical analysis was performed using a paired t-test (Statview).
Results: In FDT, mean deviation decreased significantly from 3.86 ± 0.9 db before to 0.49 ± 1.9 after ethyl alcohol intake (p= 0.007), whereas PSD did not change significantly
(p = 0.70). In SWAP, neither MD nor PSD showed significant changes after alcohol
ingestion (p = 0.94 and p = 0.62, respectively). Mean IOP decreased from 12 ±2 mmHg
before to 11 ± 2 mmHg after alcohol application (p= 0.01). Neither systemic systolic nor
diastolic blood pressure showed significant changes (p=0.20 and 0.70, respectively).
Mean blood alcohol concentration was 0.38 ± 0.16 g/l.
Conclusions: Our results show a significant decrease in mean deviation in FDT after
alcohol consumption and a slight increase in PSD indicating a general depression in
retinal sensitivity with no particular presence of focal defects. Interestingly, in SWAP
no changes were detectable. Moreover, our results indicate that low levels of blood
alcohol might lead to an IOP reduction.
CR: A. Weber, None; N. Plange, None; C. Rennings, None; M. Kaup, None; J. Huth,
None; P. Wolter, None; G. Roessler, None; T. Kirschkamp, None; A. Remky, None.
Support: None
2538-2541
2542 - A85
Do Visual Fields Change When There Are Cognitive Distractors?
B.M. Junghans, C. Yeong, G. Rennie, D.D. Athavale, Y. Yao. School of Optometry & Vis
Sci, Univ of New South Wales, UNSW Sydney, Australia.
Purpose: There is increasing concern with the frequent use of mobile phones whilst
driving. Passengers are able to see the challenges the driver faces, however the person
at the other end of the mobile phone cannot, and may demand high level cognitive
interaction of the driver at inappropriate times. This study examined the changes in
spatial sensitivity of the retina accompanying the imposition of an auditory cognitive
memory task.
Methods: The visual fields of 33 subjects aged 18 to 24 with normal scores on the Scan
C auditory figure-ground test were examined using the Medmont Monocular Driving
Visual Field threshold test following the three zone method. After a baseline visual
field test, another four identical format field tests were carried out following a Latin
Square design either with (i) no distractions (ii) with instrumental music (iii) with a
structured conversation requiring answers to questions involving spatial memory or
arithmetic (iv) with music and conversation. An ANOVA was carried out to examine
the effect of auditory distraction on the number of fixation losses, false positives, false
negatives, relative defects, absolute defects and time taken.
Results: Significant (p<0.01) increases in the number fixation losses, false positives,
false negatives, relative defects, absolute defects and time taken were found only for
the two conditions involving auditory-cognitive tasks. Analysis of the location of the
field defects revealed that there was no preference for one quadrant over another,
although analysis based on annular placement in the visual field showed greatest
resistance to field erosions in the 10-30° region followed by the periphery, the central
10° and finally the 30-50° region. Success in answering the questions posed did not
influence the outcome of the visual field test.
Conclusions: Involvement in auditory-driven cognitive load impacts visual attention,
accuracy and response time and may be explained by Pashler’s Bottleneck Theory
of Working Memory, where ultimately attention to the cognitive task is given
precedence over performance on the visual field test. Current calls to limit mobile
phone conversations that require important decision-making would appear to have
sound basis in science.
CR: B.M. Junghans, None; C. Yeong, None; G. Rennie, None; D.D. Athavale, None; Y.
Yao, None.
Support: None
2543 - A86
An Automated Visual Field Assessment Technique for Children Utilising Eye
Tracking
I.C. Murray1A, B.W. Fleck1A, H.M. Brash1, M.E. MacRae2, R.A. Minns1A. AChild Life
and Health, 1University of Edinburgh, Edinburgh, United Kingdom; 2Princess
Alexandra Eye Pavilion, Edinburgh, United Kingdom.
Purpose: To develop a novel system employing eye tracking technology for performing
automated static perimetry (ASP) in children, and to assess its feasibility as a diagnostic
technique.
Methods: The system comprises a personal computer, display screen and an eye tracking
device to detect a child’s gaze point in real time when a stimulus is presented in their visual
field. The reflexive saccadic eye movement to fixate on the stimulus if seen can be detected
and measured. Repeating the process allows a visual field map to be built up.
The eye tracking device (Tobii X50, Tobii Technology) requires nothing fixed to the child’s
head allowing free head movement. It also supplies real time data on the position of the
child’s eyes thus allowing the calculation of the appropriate position and size of the next
visual field point stimulus.
Subjects were recruited to assess the viability of the technique. These included 6 children
with suspected visual field loss, 8 adults with known visual field defect and 11 normal
subjects. Subjects performed tests designed to replicate the Humphrey Field Analyser’s C-40
suprathreshold screening test with stimulus size Goldmann III and intensity 20dB in each
eye. Binocular testing was also carried out in the children. Adults performed the equivalent
Humphrey test for comparison.
Results: In healthy eyes of all subjects over 98% of points agreed with a normal visual
field (including blind spot). Good agreement was also found between tests performed
by adults with field defects performing both the eye tracking test and Humphrey C-40
screening test.
In children, as well as confirming full fields in healthy eyes, visual field defects were identified.
The figure shows the binocular visual field result from the eye tracking system of a 4 year
old with clinically suspected left homonymous hemianopia.
Conclusion: The results demonstrate that ASP utilising eye tracking is a promising method
of perimetry for use with children. A full validation trial of the technique is underway,
however this initial feasibility study demonstrates potential in the technique.
CR: I.C. Murray, None; B.W. Fleck, None; H.M. Brash, None; M.E. MacRae, None; R.A.
Minns, None.
Support: Mackay Trust
2544 - A87
Binocular Remote Gaze Estimation System for Infants
2545 - A88
Variation of Stereothreshold With Random-Dot Density
M. Eizenman1A, E.D. Guestrin1B, C.A. Westall1C, NSERC. AOphthalmology, Biomedical
Engineering, BBiomedical Engineering, COphthalmology, 1University of Toronto,
Toronto, ON, Canada.
L. Gantz, H.E. Bedell. College of Optometry, University of Houston, Houston, TX.
Purpose: The forced choice preferential looking technique is a standard technique
to evaluate visual acuity in infants. This technique is based on infants’ preference
to look at patterns rather than homogenous fields. This study describes a novel
remote gaze estimation system that records infants’ visual scanning patterns for
objective determination of infants’ preference when viewing simultaneously presented
patterned and homogeneous fields.
Methods: By using at least 2 video cameras to record images of the subject’s eyes and
at least 2 light sources to illuminate the eyes, it is possible to estimate the point-of-gaze
in the presence of head movements after completing a simple single-point calibration
procedure. The point-of-gaze is estimated from the coordinates of the centers of the
pupil and corneal reflections extracted from the video images. A system with 2 cameras
and 4 light sources was implemented and optimized for the estimation of infants’
point-of-gaze. For the calibration procedure, the system presented a bright looming
stimulus for about 3 seconds to attract the infant’s attention.
Results: The accuracy of the system was evaluated first monocularly with 3 adult
subjects who fixated on 25 points on a computer screen at 5 different head positions
(head positions were within a volume of 10*8*10 cm 3). The RMS point-of-gaze
estimation errors for the 3 subjects were 6.6 mm (~0.6°), 6.7 mm and 11.2 mm (~1°).
The overall system performance was then evaluated binocularly with two infants (6
and 7 months old) who, while seating on their parent’s lap, viewed a looming stimulus
that was presented at several random positions on the computer screen. Whenever
the infants looked at the visual stimulus, the point-of-gaze estimates were within ~30
mm (~2.6°) from the center of the stimulus.
Conclusions: This remote gaze estimation system, which requires a single-point
calibration, can be used to record infants’ visual scanning patterns. The accuracy of the
system supports robust computation of parameters (e.g. order and duration of fixations)
that can be used for the objective determination of infants’ looking preference.
CR: M. Eizenman, EL-MAR Inc., P; E.D. Guestrin, None; C.A. Westall, None.
Support: NSERC Canada
Purpose: Stereothresholds measured with local-contour stereograms are typically
lower than those measured with complex random-dot stereograms (RDSs). These
dissimilar thresholds may be due to differences in the characteristics of local and
global stereograms, e.g., spatial frequency content, contrast, inter-element separation,
or area. Because the density of stimulus elements generally differs between local
and global stereograms, the goal of this study was to compare stereothresholds
for a short line segment presented against static and dynamic RD backgrounds of
various densities.
Methods: The stimuli were RDSs programmed in MATLAB with the psychtoolbox
extension. Each dot was convolved with a 2D Gaussian distribution to allow subpixel
resolution. Four corrected observers with normal binocular vision judged the depth of
a line (0.85’ x 11’) presented near the center of each 171’ x 171’ stereogram. Dot density
in the stereogram ranged from 0.75% (4 dots) to 15% (841 dots). Stimuli were presented
in a dark room at a distance of 114 cm using a mirror haploscope. The target line and
background dots were matched in detectablity for each RDS density by presenting
the stimuli at a fixed multiple of the contrast-detection threshold. Stereothresholds
were defined as the semi-interquartile range of the cumulative Gaussian function, fit
to the percentage of near responses as a function of the line disparity.
Results: Stereothresholds average approximately 12” for a static RD density of 2.7%,
and 14” for a dynamic RD density of 1.77%, and approximately double for both lower
and higher densities.
Conclusions: Based on previous results, the increase in stereothresholds as dot
density increases is not due to a change in the number of RDs. Different processes
are likely to increase stereothresholds for low vs. high RD background density.
Specifically, the increase in stereothresholds at low densities is likely due to the
increased spacing between elements, which reduces their usefulness as a reference
for relative disparity judgments. The increase in stereothresholds at high densities
is likely to result from a crowding effect. However, similar stereothresholds can be
obtained for RD backgrounds of low and high density.
CR: L. Gantz, None; H.E. Bedell, None.
Support: University of Houston VRSG, NIH Core Grant P30 EY07751
2542-2545
2546 - A89
Perception of Spatial Depth in Goldfish
B. Frech, C. Neumeyer. Institut fuer Zoologie (Neurobiologie), J. Gutenberg
Universitaet, D - 55099 Mainz, Germany.
Purpose: The perception of spatial depth is crucial for most animals in a 3-dimensional
surrounding. To get depth information from a 2-dimensional retinal image, it has
to be analysed in many different ways. Some cues to perceive depth are binocular
disparities, motion parallax and accommodation. Although the visual system of the
goldfish is intensively studied, it is not known in what quality they can discriminate
distances in spatial depth and which retinal image cues are crucial for the performance
of depth perception. In a first approach we investigated how good goldfish are in
discriminating different object distances in spatial depth.
Methods: Three goldfish were trained to discriminate between two equally sized
objects. The stimuli consisted of two black disks with 4,5 cm diameter placed in a
homogenous white surrounding. They were presented in different distances in a two
alternative forced choice task. Goldfish were trained to choose the near disk (training
stimulus) while the other (test stimulus) was first shown as far from the training
stimulus as possible. Three experiments were done in which the training stimulus
was situated at 5, 7 and 10 cm. One goldfish was trained on the distant stimulus (25,
30 and 40 cm) and tested against a near stimulus. The distance between training and
test stimulus was decreased until the choice frequency for the training stimulus
dropped under the threshold value of 75%. All stimuli combinations were at least
shown in 15 trials containing 100 choices.
Results: All goldfish were perfectly able to learn the discrimination task with every
training stimulus position. In each experiment the results are similar for all fish: When
the distance between the stimuli was diminished, the choice rate remains constant up
to a certain point after which it declines rapidly. The smallest inter-stimuli distances
with 75% choice frequency for the three goldfish trained on the near stimulus were
5; 5,5 and 7,5 cm and for the goldfish trained on the distant stimulus 12,5; 17,5 and
20 cm respectively. This shows clearly that the discrimination ability of the goldfish
decreases with increasing training stimulus distance: the nearer the training stimulus
is to the goldfish, the better.
Conclusions: The distance dependent decrease of the discrimination ability shows
that goldfish do not discriminate the objects through size discrimination by use of
the size difference of the retinal image, but that the distance has a great influence on
their performance. We assume that accommodation plays an important role in depth
discrimination, which we will investigate in further experiments.
CR: B. Frech, None; C. Neumeyer, None.
Support: DFG (Ne 215/12-1)
2546
Tuesday, April 29, 11:15 AM - 1:00 PM Room 305 Paper Session Program Number Range: 2836-2842
337. Aberrations and Visual Performance Organizing Section: VI
2836 - 11:15AM
Impact of Fundus Structure on Wavefront Sensing of Ocular Aberrations
2837 - 11:30AM
Effects of Higher Order Aberrations on Night Myopia Using Adaptive Optics
W. Gao, B. Cense, C. Zhu, R.S. Jonnal, D.T. Miller. School of Optometry, Indiana
University, Bloomington, IN.
G. Yoon1A,1B, R. Sabesan1B,1C, M. Gilbert1C. ADepartment of Ophthalmologty, BInstitute
of Optics, CCenter for Visual Science, 1University of Rochester, Rochester, NY.
Purpose: Objective wavefront sensors, in particular those based on Shack-Hartmann
(S-H) technology, are routinely used for measuring ocular aberrations in the eye.
Accuracy and precision of these instruments depend on the instrumentation, but also
on properties of the eye. In particular, wavefront sensors rely on a focused beam of
near infrared light that reflects from the thick fundus. Current sensors assume light is
reflected from a single retinal plane presumed to be near the photoreceptor apertures.
This assumption fails to account for errors potentially introduced by reflections from
many depths in the thick fundus. To predict this error, we developed an optical model
of the fundus reflection in conjunction with the physical principles that govern light
propagation through the eye and wavefront sensor.
Methods: An axial reflectance profile of the fundus was constructed from averaged
A-scan images acquired in several subjects at 2 degree retinal eccentricity using
spectral domain OCT (λc=840 nm, Δλ=50 nm). The optical Stiles-Crawford effect
was incorporated using directionality parameters of 0.06 and 0.12 for the reflections
at the cilia junction and posterior outer segment tip, respectively. The contribution of
the choroid was systematically varied over a range of expected values that account
for possible differences in detection between SD-OCT and S-H wavefront sensors.
Reflections from the thick fundus were propagated through an ideal eye (no ocular
aberrations) and then sampled by an 11x11 lenslet array that spanned an 8 mm pupil at
the eye. Centroids were obtained from the lenslet focal spots. Corresponding wavefront
slopes were fit to the derivatives of Zernike polynomials up through sixth order.
Results: The numerical simulation predicts that reflections from the thick fundus
produce rotationally symmetric aberrations in the wavefront sensor measurements.
The dominant component is defocus followed by spherical aberration. Their combined
magnitude does not exceed ¼ diopter for the parameters considered here though the
value is highly sensitive to the choroid contribution and the axial location at which
the light exits the cone apertures.
Conclusions: Reflections from the thick fundus are predicted to induce ghost
aberrations in S-H sensor measurements.
CR: W. Gao, None; B. Cense, None; C. Zhu, None; R.S. Jonnal, None; D.T. Miller,
None.
Support: NEI 1R01EY018339, NEI 5R01 EY014743, and Center for Adaptive Optics
STC 5-24182.
Purpose: To assess whether or not higher order aberrations, especially spherical
aberration are partially responsible for causing night myopia in normal young
eyes.
Methods: Five normal young subjects (5 eyes) participated in the study. Subject’s
refractive errors were measured for 3 mm and 6 mm pupils at photopic (100 cd/m 2)
and mesopic (0.1 cd/m 2) luminance levels, respectively. Subject’s pupil was dilated
with Phenylephrine Hydrochloride (2.5%) and the pupil sizes were controlled with
an artificial aperture placed in pupil conjugate. Myopic shifts of the refractive error
under the mesopic condition were measured with and without spherical aberration
corrected. An adaptive optics system (AO) was used to measure and to correct
spherical aberration. The polychromatic modulation transfer functions (MTF) based
on photopic and mesopic spectral luminous efficiencies were also calculated for each
of the experimental conditions.
Results: RMS values of spherical aberration under photopic and mesopic conditions
for a 6 mm pupil were 0.17±0.15 µm and 0.15±0.16 µm on average, respectively. Other
higher order aberrations did not significantly differ between the two conditions.
With AO correction, spherical aberration was reduced to 0.016±0.017 µm. Average
magnitudes of night myopic shift with and without spherical aberration corrected
were -0.95±0.57 D and -0.80±0.49 D, respectively. This difference was statistically
insignificant (p = 0.11). The MTF calculations showed that chromatic aberration may
contribute approximately -0.2D of night myopia.
Conclusions: In young normal eyes, monochromatic spherical aberration does not have
a significant impact on night myopia. Night myopia does not cause changes in higher
order aberrations. Contribution of the difference in spectral sensitivity of cones and
rods to night myopia may be relatively small, but significant. The predominant cause
of night myopia seems to be an involuntary accommodative state of the crystalline
lens under dim light condition.
CR: G. Yoon, Bausch and Lomb, F; Bausch and Lomb, C; R. Sabesan, None; M.
Gilbert, None.
Support: NIH/NEI grant R01EY014999, Research to Prevent Blindness
2838 - 11:45AM
Peripheral Higher Order Aberrations in Emmetropes and Myopes
2839 - 12:00PM
Modeling the Mechanism of Compensation of Aberrations for Accommodation
and Age
A. Mathur, D.A. Atchison, D.H. Scott. Optometry, QUT School of Optometry, Kelvin
Grove Brisbane, Australia.
Purpose: Poor image quality in the peripheral field may lead to myopia. Most studies
measuring the higher order aberrations in the periphery have been restricted to
the horizontal visual field. The purpose of this study was to measure higher order
monochromatic aberrations across the central 42º horizontal x 32º vertical visual
fields in myopes and emmetropes.
Methods: We recruited 5 young emmetropes with spherical equivalent refractions
+0.17 ± 0.45D and 5 young myopes with spherical equivalent refractions -3.9 ± 2.09D.
Measurements were taken with a modified COAS-HD Hartmann-Shack aberrometer
(Wavefront Sciences Inc). Measurements were taken while the subjects looked at
38 points arranged in a 7 x 6 matrix (excluding four corner points) through a beam
splitter held between the instrument and the eye. A combination of the instrument’s
software and our own software was used to estimate OSA Zernike coefficients for
5mm pupil diameter at 555nm for each point. The software took into account the
elliptical shape of the off-axis pupil. Nasal and superior fields were taken to have
positive x and y signs, respectively.
Results: The total higher order RMS (HORMS) was similar on-axis for emmetropes
(0.16 ± 0.02 μm) and myopes (0.17 ± 0.02 μm). There was no common pattern for
HORMS for emmetropes across the visual field where as 4 out of 5 myopes showed a
linear increase in HORMS in all directions away from the minimum. For all subjects,
vertical and horizontal comas showed linear changes across the visual field. The
mean rate of change of vertical coma across the vertical meridian was significantly
lower (p = 0.008) for emmetropes (-0.005 ± 0.002 μm/deg) than for myopes (-0.013 ±
0.004 μm/deg). The mean rate of change of horizontal coma across the horizontal
meridian was lower (p = 0.07) for emmetropes (-0.006 ± 0.003 μm/deg) than myopes
(-0.011 ± 0.004 μm/deg).
Conclusions: We have found differences in patterns of higher order aberrations across
the visual fields of emmetropes and myopes, with myopes showing the greater rates
of change of horizontal and vertical coma.
CR: A. Mathur, None; D.A. Atchison, None; D.H. Scott, None.
Support: None
J. Tabernero, P. Artal. Laboratorio de Optica, Universidad de Murcia, Murcia, Spain.
Purpose: To investigate the potential changes in the amount of compensation of
aberrations as a result of the changes in lens shape factor (curvature) and asphericity
of the crystalline lens as a function of accommodation and age.
Methods: We measured corneal and ocular aberrations, lens alignment, and axial
length of the eye in a group of 18 young subjects. These data were used to develop
individualized models for the unaccommodated eye [Tabernero et al., JOSAA, 2007].
The curvature and asphericity of the crystalline lenses were selected to match
the refraction and spherical aberration of each eye. This correctly predicted the
compensation of coma. To evaluate the effect of the geometrical changes of the lens
due to accommodation and age on the compensation of aberrations, we used the
average geometrical data available in the literature [Dubbelman et al., Vis. Res, 2005;
Dubbelman & Van der Heijde, Vis.Res., 2001]. These changes were incorporated in
each individual eye model. The eye’s aberrations were calculated, using exact raytracing, every 0.25 D of accommodation (from 0 to 7 D.) and every 5 years of change
in lens parameters (from 20 to 75 years old).
Results: The change in the crystalline lens curvatures (shape factor) occurring during
accommodation predicts well the change in ocular spherical aberration (SA) with
a sign reversing from positive to negative. The changes in lens asphericity with
accommodation have a smaller effect in the evolution of SA. During accommodation
coma changed less than SA. This made the balance of aberrations between cornea
and lens rather stable. This result could also be explained by Seidel aberration theory.
The change in power of the lens would increase coma, but on the other hand, the
change in shape factor towards a more equibiconvex lens counteracts in part this
effect. The scenario is slightly different when age is considered. In order to explain
the increase in ocular SA and coma with age [Artal et al., JOSA A, 2002], the increase
in asphericity of the lens surfaces need to be incorporated in the modeling. The
change in lens curvature alone cannot be responsible for this effect, since it would
only generate a similar situation as lens accommodation: a decrease in SA; which is
against the experimental results.
Conclusions: The mechanism of compensation of aberration between the cornea and
lens is some how disrupted both during accommodation and aging. We used customized
modeling to evaluate the effect of the change sin lens curvatures and asphericity in
this mechanism. The curvatures in the case of accommodation and asphericity in the
case of aging is the main responsible for the changes in aberrations
CR: J. Tabernero, None; P. Artal, None.
Support: MEC_FIS2004-2153 (Spain)
2836-2839
Tuesday, April 29, 11:15 AM - 1:00 PM Room 305 Paper Session Program Number Range: 2836-2842
337. Aberrations and Visual Performance Organizing Section: VI
2840 - 12:15PM
Change in Retinal Image Quality for Physiologic Pupil Diameters Does Not
Account for the Loss of logMAR Acuity With Age
2841 - 12:30PM
Effect of Adaptive-Optics-Corrected Ocular Aberrations on Visual Acuity as a
Function of Luminance and Polarity
R.A. Applegate1, L.N. Thibos2, J.D. Marsack1, H.M. Queener1, D.E. Koenig1. 1Visual
Optics Inst/Coll of Optometry, University of Houston, Houston, TX; 2School of
Optometery, Indiana University, Bloomington, IN.
L. Sawides, C. Dorronsoro, E. Gambra, S. Marcos. Instituto de Optica, C.S.I.C., Madrid,
Spain.
Background: Elliott et al found ~0.1 logMAR (1 line) drop in average high contrast
acuity between the ages of 20 and 80 (Optom Vis Sci 72: 186 - 91, 1995). The Texas
Investigation of Normal and Cataract Optics found a 0.275 logMAR (2 and ¾ line)
loss in average low luminance, low contrast acuity over the same age range. When
pupil diameter is adjusted for typical age and luminance effects, average HO RMS
WFE remains essentially constant as a function of age (J Opt Soc Am-A 24:578-87,
2007). HO RMS WFE is not the best retinal image quality metric for predicting visual
performance. More sensitive retinal image quality metrics predict ~40% of the variance
in low luminance, low contrast acuity (Opt Vis Sci 83:635-40, 2006).
Purpose: To model, using physiologic pupil diameters, whether or not decreases in
retinal image quality can account for the loss in low luminance, low contrast visual
acuity with increasing age.
Methods: WFE was measured on one eye of each of 148 subjects with their pupils
dilated. The WFE was fit with a normalized Zernike polynomial following the
recommendations of the ANSI Z80.28 standard. The Zernike coefficients were then
scaled to age and luminance appropriate (9 cd/m 2) physiological pupil diameters
based on data from Winn et al (IOVS 35: 1132 - 37). The scaled Zernike coefficients
were in turn used to calculate the 3 top retinal image quality metrics (log PFSc, log
AREA OTF, and log SFc OTF) for predicting low luminance, low contrast logMAR
acuity (Optom Vis Sci 83:635-40,2006) and regressed against age.
Results: Each retinal image quality metric, when corrected for age and luminance
appropriate pupil diameter, decreased slightly with increasing age over the 60 year
time span (20 - 80). Age accounted for between 3 and 12% of the variance in the retinal
image quality metrics. The expected average decrease in low luminance, low contrast
logMAR acuity due to the decrease in retinal image quality over the 60 year time span
is between 1 and 1 ½ letters.
Conclusions: When WFE is scaled to correct pupil diameter for luminance and age,
metrics of retinal image quality decrease only slightly with age and cannot account for
the loss of either low or high contrast logMAR acuity at either low or high light levels.
This finding suggests that factors such as scatter and/or losses in neural processing
account for the majority of acuity loss with age.
CR: R.A. Applegate, University of Houston, P; L.N. Thibos, Indiana University,
P; J.D. Marsack, None; H.M. Queener, None; D.E. Koenig, None.
Support: R01 EY08520 (RAA); P30 EY 07551; EY O5109 (LNT)
Purpose: To investigate the effect of correcting ocular aberrations on visual acuity
(VA), both for white-on-black (WoB) and black-on-white (BoW) letters at various
luminances. To assess the relative contribution of optical and neural factors to the
visual acuity measured in those conditions.
Methods: We measured VA with natural aberrations and under static aberration
correction with adaptive optics (AO). The custom-made instrument included a
Hartmann-Shack wavefront sensor, a magnetic deformable mirror with 52 actuators
(MIRAO, Imagine Eyes), a motorized Badal system, a pupil monitoring CCD, and a high
brightness minidisplay. VA was measured using a four alternative choice procedure
with tumbling Snellen E letters (Quest algorithm with 50 trials presented during 0.5 s,
programmed in Psychotoolbox). VA was measured as a function of luminance (0.8, 1.6,
2.5, 5, 16, 25 and 50 cd/m2), starting with the dimmest test, and allowing for adaptation.
Three conditions were measured: WoB letters under natural conditions, WoB and BoW
letters under dilation and 6-mm artificial pupils. For each luminance and polarity
condition, VA was measured with/without the subject’s aberrations in random order.
Pupil size, centration and aberrations were continuously assessed. Four subjects (age:
29.5±4.4 years; spherical error: -3.00±2.05D; cylinder<0.5 D) were tested.
Results: 1) Mean RMS wavefront error was 0.673±0.120, corrected down to 0.178±0.027
(up to 85% correction). 2) Except for one eye (with the lowest amount of natural
aberrations), VA increased significantly with AO correction for all luminance and
polarity conditions, by a factor of 1.23 on average. 3) BoW VA increased consistently
with luminance, with and without AO correction; WoB tended to show an inverted
“U” behavior with luminance, becoming flatter with AO correction (both for dilated
and natural pupils). 4) For intermediate luminances WoB VA was higher than BoW,
but the difference decreased with AO correction. 5) For both polarities, the largest VA
increase with OA correction occurred at the lowest luminances. For intermediate and
high luminances, the AO VA improvement was higher for BoW than WoB letters.
Conclusions: 1) In most eyes, correction of ocular aberrations resulted in a significant
increase of VA at all luminance and polarity levels. 2) Ocular aberrations play a role
in the differences of VA with polarity. 3) The relative change of VA with luminance
is primarily determined by neural factors.
CR: L. Sawides, None; C. Dorronsoro, None; E. Gambra, None; S. Marcos, None.
Support: MEyC FIS2005-04382 and EURYI Award to SM; MEyC FPI Predoctoral
Fellowship to LS; CSIC I3P Predoctoral Fellowship to EG
2842 - 12:45PM
Short-Term Visual Benefit of Correcting Higher Order Aberrations in
Keratoconic Eyes
R. Sabesan1A,1B, G. Yoon1C,1A. AInstitute of Optics, BCenter for Visual Science,
C
Department of Ophthalmology, 1University of Rochester, Rochester, NY.
Purpose: To investigate whether or not keratoconic eyes can achieve perfect visual
performance when their ocular aberrations are corrected nearly to the diffractionlimit using large-stroke adaptive optics
Methods: An adaptive optics system equipped with a large-stroke deformable mirror
and a Shack Hartmann wavefront sensor was used to correct the aberrations in 5
normal and 7 keratoconic eyes over a 6 mm pupil. Defocus and astigmatism were
partially compensated using a Badal system and a phoropter in keratoconic eyes,
prior to closed-loop correction, to conserve the dynamic range of the mirror. High
deformable mirror gain was employed to ensure the stability of closed-loop correction.
High contrast visual acuity was measured using tumbling letter ‘E’ test over a 6-mm
pupil in both groups. Stable optical quality was provided with dynamic closed-loop
adaptive optics during visual acuity test.
Results: After adaptive optics correction, the average residual rms in normal and
keratoconic eyes was 0.08 ± 0.025µm and 0.1 ± 0.015 µm respectively over a 6mm pupil
and they were not significantly different (p = 0.174). High deformable mirror gain
allowed rapid convergence of aberration correction within 3-5 iterations. In addition, it
also helped to maintain a stable residual error during the visual acuity test. Averaged
variability of dynamic correction performance, defined as the standard deviation
of residual RMS during acuity test, was 0.025 ± 0.014 µm. The average high contrast
visual acuity in normal eyes was -0.24 ±0.071 logMAR over a 6-mm pupil, while that
in keratoconic eyes was -0.08±0.055 logMAR. Difference in visual acuity between
keratoconic and normal eyes was observed to be statistically significant (p = 0.004).
Conclusions: With the same perfect optical quality, visual performance is significantly
worse in keratoconic eyes compared to normal eyes. Long-term visual experience with
poor retinal image quality, induced by higher order aberrations, may be restricting the
visual benefit achievable immediately after correction in keratoconic eyes. However,
maximum predicted visual performance might be expected in these eyes after long
term adaptation of the visual system to near-diffraction limited ocular optics.
CR: R. Sabesan, None; G. Yoon, Bausch and Lomb, F; Bausch and Lomb, C.
Support: NIH/NEI grant R01EY 014999 and Research to Prevent Blindness
2840-2842
Tuesday, April 29, 11:15 AM - 1:00 PM Hall B/C Poster Session Program Number/Board # Range: 2887-2898 / A90-A101
345. Visual Function in Aging and Disease Organizing Section: VI Contributing Section: RC
2887 - A90
Ageing Effects on Central and Peripheral Visual Performance
2888 - A91
Closed Road Driving Performance: Evidence for a Front Speech Advantage for
Older Drivers
F.G. Rauscher, D.F. Edgar, J.L. Barbur. App Vis Res Ctr, City University London,
London, United Kingdom.
Purpose: Detection Thresholds (DT), Contrast Acuity (CA), Motion Perception (Mot)
and Colour Vision (Col) were tested in 200 subjects at the fovea and in the periphery
(6° away from fixation into each quadrant) to establish age-matched control data of
different aspects of visual performance.
Methods: Ageing is known to affect visual performance, due to changes in the optics
in the eye and the retina. Visual performance was assessed in a number of normal
healthy subjects (spread evenly from 20 to 80 years of age). All subjects had Visual
Acuity (VA) of 20/20 or better. The tests were carried out on the P_SCAN system and
fixation stability was monitored using eye-movements. Target size was adjusted in
size for peripheral locations to account for retinal and cortical magnification (Landolt
ring for DT and CA from 14 min of arc to 38 min of arc). Colour vision assessment
employed the CAD test and was restricted to yellow-blue and red-green axes.
Results: Absolute DT showed a significant dependence on age both in the fovea and
the periphery for each subject group (decades). CA data for fovea and periphery
could be statistically combined (size adjusted) with an increase in threshold with
age. Motion thresholds were less influenced by age. Subjects showed no significant
statistical difference below 50 years of age in combined data. Red-green and yellowblue colour thresholds were analysed separately at the fovea and in the periphery
and showed no effect of ageing below 60 years.
Conclusions: Gradual loss of DT and CA was found, confirming a reduction in VA
with age. Motion (<50) and colour (<60) thresholds were less affected. Selective loss
of visual functions with ageing was found to have a significant impact on central and
peripheral threshold data. Our findings have clinical relevance in differentiating
disease processes and making early diagnosis, this is crucial when disease tends
to be more frequent with advancing age. Selective age ranges allowed performance
limits to be established, providing a basis on which to assess the differential effect
of ageing on different visual mechanisms.
CR: F.G. Rauscher, None; D.F. Edgar, None; J.L. Barbur, None.
Support: None
A. Chaparro1, J. Wood2. 1Department of Psychology, Wichita State University,
Wichita, KS; 2School of Optometry and Institute of Health and Biomedical
Innovation, Queensland University of Technology, Brisbane, Australia.
Purpose: Previous research using a driving simulator has demonstrated that drivers
find it easier to shadow an auditory channel when the information is presented through
a speaker positioned directly in front of them, rather than one positioned to their side.
The aim of this study was to determine whether this effect is also obtained under
more realistic driving conditions where participants drive a vehicle around a closed
road course and assess whether older adults, who experience greater difficulties under
dual-task conditions, derive similar advantages from changes in speaker position
Methods: The impact of the location of an auditory secondary task on measures of
driving performance including the recognition of road signs, detection and avoidance
of large low contrast hazards, gap judgment and time to complete the course was
obtained for young and older participants as they drove along a closed road driving
course. Ten young (Mean age = 26.9 years, SD=4.2) and nine elderly (Mean age = 72.4
years, SD=4.2) participants with normal corrected vision completed the experiment. A
composite driving score was also derived to capture the overall driving performance
of the individual participants compared to the whole group and included road sign
recognition, cone gap perception, course time and the number of road hazards hit;
this latter measure was selected rather than including both road hazards seen
Results: The interaction of position and age was marginally significant (p=.07) for
the composite Z-score. The composite score indicates that whereas the older adults
performed better when the speaker was in the front position, the performance of
younger adults worsened. The effect of speaker position on time to complete the road
course was marginally significant, (p =.07) with drivers completing the course more
quickly when the speaker was mounted on the front position.
Conclusions: The driving measures show that older adults driving performance
improved when the direction of spatial visual attention and the location from which
the secondary auditory task emanated was congruent.
CR: A. Chaparro, None; J. Wood, None.
Support: None
2889 - A92
Association Between Moderate Hearing Loss and Vision in a Population of
Elders
2890 - A93
Sampling Efficiency and Internal Noise in Young Patients With and Without
Symptomatic Visual Motion Impairment
M.E. Schneck1, L.A. Lott1, G. Haegerström-Portnoy2,1, J.A. Brabyn1. 1Smith-Kettlewell
Eye Research Institute, San Francisco, CA; 2School of Optometry, University of
California, Berkeley, Berkeley, CA.
H.K. Falkenberg1, W.A. Simpson2, G.N. Dutton 3. 1Department of Optometry & Visual
Science, Buskerud University College, Kongsberg, Norway; 2School of Psychology,
University of Plymouth, Plymouth, United Kingdom; 3Department of Optometry &
Vision Sciences, Glasgow Caledonian University, Glasgow, United Kingdom.
Purpose: To examine the association between hearing deficits and vision in an older
population of community dwelling individuals.
Methods: A vision test battery and a screening test of hearing (40 db tones presented
monaurally twice per ear at 500, 2000, 4000 Hz) were administered to 446 older adults
(aged 67 - 107, mean 79.9, median 78.6). Vision was tested binocularly with habitual
correction, and all vision tests were graded on a logarithmic scale. Hearing was graded
as pass or fail (failure: heard no tones in either ear). Other factors considered were age,
sex, education level, depression status, smoking status, history of cataract (medical
records or self-report), and self-reported presence/absence of six medical conditions
(heart disease, hypertension, diabetes, stroke, cancer and arthritis).
Results: In preliminary univariate analyses, each vision measure was significantly
related to hearing status (poorer vision, poorer hearing). However, in logistic regression
models controlling for age, we found that high contrast acuity, low contrast (~16%)
acuity, contrast sensitivity, glare recovery time and stereopsis were not related to
hearing loss. In these models, only SKILL Dark acuity (low contrast, low luminance
acuity), low contrast (~10%) acuity, and glare disability were significantly associated
with moderate hearing loss. In addition, history of cataract surgery and self-reported
history of stroke were independently associated with hearing status. In stepwise
analyses including variables that were significantly associated with hearing, SKILL
Dark acuity, age and history of cataract surgery were significantly associated with
hearing status. However, substituting either low contrast (10%) acuity or acuity in
the presence of disability glare yielded similar results.
Conclusions: In the current study, we find no association between high contrast
acuity and hearing loss (when age is taken into account). However, low contrast
measures of acuity (SKILL Dark Acuity, low contrast (10%) acuity, or low contrast
acuity in glare) were associated with moderate hearing impairment. Further, our
results agree with others that have shown that hearing impairment is associated
with (some types of) cataract.
CR: M.E. Schneck, None; L.A. Lott, None; G. Haegerström-Portnoy, None; J.A.
Brabyn, None.
Support: Supported by NIH EY09588 to JAB and SKERI
Purpose: Impaired motion perception has been found in child patients with
hydrocephalus and children with more diffuse cerebral damage, often in the presence
of otherwise near normal visual functions. This study investigates how child patients
with symptomatic motion impairments and children with hydrocephalus without
impaired motion perception are limited by internal noise and sampling efficiency.
Methods: Energy contrast thresholds were measured as a function of external
dynamic noise level in three tasks: detection of a drifting grating, detection of the
sum of two oppositely drifting gratings and direction discrimination of oppositely
drifting gratings. Thresholds were measured in seven child patients with and without
symptomatic motion impairments, and in 168 children (5-14 years) with normal
visual development.
Results: Motion detection, summation and discrimination are impaired in patients
with symptomatic motion impairments (p< .05). This is due to both increased levels
of internal noise and reduced sampling efficiency. Children with hydrocephalus
without symptomatic motion impairments perform equally well to child observers
with normal development. Sampling efficiency for direction discrimination is much
poorer in children than adults (p< .05), and is not yet mature by 14 years of age, in
contrast to sampling efficiency for detection and summation which do not change
with age. The internal noise levels do not change with age or task.
Conclusions: Patients with symptomatic impairment of motion perception have higher
internal noise and lower sampling efficiency than children with normal development
and patients without symptoms. It is also clear that motion direction discrimination is a
difficult task for the visual system; the absolute efficiency is poor (< 2 %), and direction
discrimination is not fully developed even in young teenagers. This suggests that
motion detection and motion discrimination are processed by different mechanisms
that have different maturation periods.
CR: H.K. Falkenberg, None; W.A. Simpson, None; G.N. Dutton, None.
Support: None
2887-2890
2891 - A94
Visual Fields in Children Treated With Vigabatrin
S. Agrawal, D. Mayer, R. Hansen, A. Fulton. Ophthalmology, Childrens Hospital and
Harvard Medical School, Boston, MA.
Purpose: Develop a method for assessment of peripheral visual fields (VF) in young
children treated with Vigabatrin (VGB), an anti-epileptic medication. Bilateral
VF constriction occurs in ~30% of VGB treated adults. In children too young for
conventional VF testing, current practice is to use electroretinography for surveillance
of adverse effects of VGB.
Methods: VF extent on the diagonal meridia in four quadrants was assessed
monocularly and binocularly with two kinetic methods: white sphere kinetic
perimetry (WSKP; Delaney et al, 2000), using a 6° white sphere on a black background,
and Goldmann kinetic perimetry (GKP), using a 1.7° diameter light on a 10 cd/m2
background. In addition, thresholds for detecting 2°, 50 ms lights at 10° and 30°
eccentric were determined in the dark adapted condition and in the presence of a
10 cd/m2 background (Hansen & Fulton, 1995). These procedures were evaluated
in five VGB treated children, one with known VF constriction (9 years old) and four
younger children (3-8 years old). Their data were compared to data from age-similar
controls.
Results: For the 9 year old, there was good agreement between GKP and WSKP in
VF extent on all four meridia. In all four quadrants, this child’s GKP and WKSP fields
were significantly constricted by 25° or more (>2SD from the normal mean). Three of
the other children (age 4-8 years) could be tested monocularly with both GKP and
WSKP, and both methods showed extents within 1SD of the normal mean. In these
children, the binocular VF extent equaled the temporal monocular VF. In the 3 year
old, monocular testing could not be completed; binocular testing showed the extent
in each quadrant equaled the temporal monocular VF in normal 4 year old. All five
children had measurable dark and light adapted thresholds. The only abnormality was
elevation of the light adapted thresholds in the 9 year old with VF constriction.
Conclusions: Assessment of VF extents using WSKP and psychophysical threshold
measurements was feasible in VGB treated children. The results suggest that VF extent
using these procedures will be sensitive to VGB induced VF deficits.
CR: S. Agrawal, None; D. Mayer, None; R. Hansen, None; A. Fulton, None.
Support: Ovation Pharmaceuticals, Inc.
2893 - A96
Visual Field Progression in Patients With Retinitis Pigmentosa
K. Holopigian1, J.M. Gallardo1, W. Seiple1, W.H. Swanson2, R.E. Carr1. 1Ophthalmology,
New York Univ School of Med, New York, NY; 2School of Optometry, Indiana
Purpose: Visual field sensitivity is a standard measure for following progression in
patients with retinitis pigmentosa (RP). Previous studies have established the rate of
progression in visual field area in patients with RP using kinetic perimetry (1-4). As
well, Birch et al (5) examined five-year changes in static perimetric thresholds averaged
across the visual field. There is, however, little information about the progression of
visual field loss in different retinal areas in patients with RP. In the current study,
we examined changes in Humphrey visual field (HVF) thresholds as a function of
retinal eccentricity in a group of patients with RP.
Methods: HVFs for one eye of thirty-nine patients with RP were compared over
follow-up periods ranging from two to twelve years (median number of visits = 4).
At the initial examination, all patients had visual acuities better than 20/40. Fullthreshold HVF testing was done using a modified program that tested 103 points
(including the fovea) corresponding to our multifocal ERG array. In a few cases, visual
field results from standard 30-2 or 10-2 full-threshold HVFs were included using a
point-by-point comparison to line up the field values. The results for each patient
were compared to those from 10 age-similar subjects with normal visual acuity and
normal HVFs by subtracting the patient threshold values from the averaged value
of the control group.
Results: The results were analyzed separately for the fovea, ring 1 (out to 5o), ring 2
(out to 10o) and the periphery (all remaining points to 25o). The data were transformed
into linear units for averaging. For each eccentricity, the median loss in sensitivity for
the patients was plotted as a function of years of follow-up and regression lines for the
data were calculated. The median HVF loss at the initial visit varied with eccentricity;
from 3.3 dB loss at the fovea to 13.8 dB loss for the periphery. In addition, the amount
of progression (slope of the regression line) increased with eccentricity, from 0.07 dB
loss/year for the fovea to 0.94 dB loss/year for the periphery. There were no significant
differences between the slopes for the fovea, 5 o or 10 o (p > 0.05) but the slope for the
peripheral data was significantly steeper than were the other slopes (p <0.05).
Conclusions: We found eccentricity-dependent rates of field progression in patients
with RP. These results have implications for current studies involving therapeutic
interventions.
References: 1. Massof, et al, 1990; 2.Berson, et al, 1985; 3. Holopigian, et al, 1996; 4.
Grover, et al, 1997; 5. Birch, et al, 1999.
CR: K. Holopigian, None; J.M. Gallardo, None; W. Seiple, None; W.H. Swanson,
None; R.E. Carr, None.
Support: Foundation Fighting Blindness
2892 - A95
Occluder Density and Visual Field Sensitivity in Control Subjects and Patients
With Retinitis Pigmentosa
J.M. Gallardo, K. Holopigian, S. Hornik, V. Greenstein. Dept of Ophthalmology, New
York Univ Sch of Medicine, New York, NY.
Purpose: Standard visual testing procedures require occlusion of the untested eye.
Typically, opaque occluders are used in clinical settings. However, there is conflicting
information in the literature as to the effects of occluder density on visual function of
control subjects. Fuhr, et al [1] compared performance with a translucent occluder to a
standard black occluder and reported that subjects experienced less “blankout” and had
small but significant (0.7 db) increases in Humphrey visual field (HVF) sensitivity with the
translucent occluder. However, Sreenivasan, et al [2] found that opaque occluders could
prevent visual field lens artifacts created by frosted cylindrical lenses. We examined the
effects of occluder density on HVF performance in control subjects and patients with
retinitis pigmentosa (RP).
Methods: Seven control subjects (mean age 46.6 + 17.3) with normal visual acuity and
normal HVF sensitivity and seven patients with RP (mean age 43.7 + 7.7) with visual
acuity of 20/160 or better and decreased HVF sensitivity participated in this study. Visual
sensitivity at the fovea and at eight locations with a radius of 5 degrees around the fovea
was measured with the HVF using a modified threshold program. For all subjects the
right eye was tested; the left eye was occluded but remained open. Two occluders were
used: a standard black occluder, which reduced retinal illumination by 3.1 log units
and a white occluder, which reduced illumination by 0.77 log units. Testing order was
counterbalanced (ABBA).
Results: For each subject, the results for each occluder were averaged. For the control
subjects, there was a significant difference between the occluders. Foveal sensitivities
were 1.86 dB higher for the translucent occluder than for the opaque one (Wilcoxon
matched-pairs signed rank test, p = 0.031). When the results for all the points were
included, the effect was smaller (0.43 dB) but still significant (signed rank test, p = 0.047).
For the patients, there was no significant difference in sensitivity when all the points
were included (difference = 0.13 dB, p = 0.438) but there was a significant difference for
the fovea (difference = 1.93 dB, p = 0.031).
Conclusions: Foveal sensitivity was decreased for the black compared to the white
occluder for both the control subjects and the patients with RP. These results have
implications for studies using the HVF to evaluate the effects of therapeutic interventions,
particularly for patients with ocular diseases such as RP who have decreased visual
field sensitivity.
1. Fuhr, et al., 1990, Arch. Ophthal, 983-8
2. Sreenivasan, et al., Clin. & Exp. Opt, 26-9
CR: J.M. Gallardo, None; K. Holopigian, None; S. Hornik, None; V. Greenstein,
None.
Support: Foundation Fighting Blindness
2894 - A97
Visual Function, Age-Related Maculopathy Stage and the Subsequent
Development of Age-Related Macular Degeneration
R.O. Beirne1, R.E. Hogg2, M.R. Stevenson2, R.S. Anderson1, U. Chakravarthy2. 1Vision
Science Research Group, University of Ulster, Coleraine, United Kingdom; 2Centre
for Ophthalmology and Vision Science, Queen’s University, Belfast, United
Kingdom.
Purpose: To investigate the relationship between baseline psychophysical measures of
visual function in age-related maculopathy (ARM) and the subsequent development of
advanced visual loss from age-related macular degeneration.
Methods: 36 participants (aged 52-85yrs) with early ARM and good acuity (≤ 0.3 logMAR) in
the study eye and advanced AMD in the fellow eye underwent a battery of psychophysical
tests at baseline examination (logMAR acuity, Pelli-Robson contrast sensitivity, photopic
and scotopic interferometric acuity, achromatic and short-wavelength-sensitive (SWS)
resolution acuity). Stereoscopic colour fundus photographs were graded using the
Wisconsin Age-Related Maculopathy Grading System (WARMGS) and features of ARM
were combined to assign a severity stage from 0 to 5 using the methods described by
the Rotterdam Eye Study. Participants clinical records were examined for a period of
up to 5 years from baseline, with participants being divided into two groups based on
whether or not the study eye lost a significant amount of visual acuity (greater than 3
lines of logMAR acuity) in this follow-up period.
Results: 8 participants suffered a significant drop in visual acuity during follow-up, while
26 participants did not. There was no significant difference in age (M=73.4 vs 71.9yrs;
p=0.63) or follow-up time (M=34.2 vs 28.5mths; p=0.34) between these two groups.
Achromatic and SWS resolution acuity were both significantly reduced at baseline in
those subjects who developed a significant loss in visual acuity compared to those who
did not (p<0.05). There was no significant difference in any of the other visual function
measures between the two groups. ARM stage at baseline was the strongest predictor
of disease progression, with a significant difference in the baseline ARM stage between
those who lost a significant amount of visual acuity over this follow-up period and those
who did not (Mann-Whitney U test, p=0.03).
Conclusions: This study has shown that although advancing ARM stage (stages 4, 5)
was the strongest predictor of subsequent visual acuity loss in this group of participants,
measures of achromatic and SWS resolution acuity in ARM have the potential to identify
those most at risk of subsequently developing significant visual loss due to AMD. Larger
longitudinal studies are required to fully investigate the relationships between ARM
stage, visual function and the development of significant visual loss and end-stage
disease.
CR: R.O. Beirne, None; R.E. Hogg, None; M.R. Stevenson, None; R.S. Anderson,
None; U. Chakravarthy, None.
Support: BBSRC ERA grant 16311
2891-2894
2895 - A98
Foveal Contrast Sensitivity Assessment in Diabetic Patients Using a Novel
Computerized Method
2896 - A99
Magnocellular and Parvocellular Contrast Sensitivity in Type 2 Diabetics With
Normal Fundus and Non-Proliferative Retinopathy
G. Katz1A, G. Treister1A, H. Levkovitch-Verbin1A, M. Belkin1A, J. Ilany1B, U. Polat1A.
A
Goldschleger Research Institute, BInstitute of Endocrinology, 1Sheba Medical
Center, Tel Hashomer, Israel.
M. Gualtieri1, M. Bandeira1, F.M. Damico1, A.L.A. Moura1, R.D. Hamer1,2, D.F. Ventura1.
1
Neuroscience and Behavior, University of Sao Paulo, Sao Paulo, Brazil; 2The SmithKettlewell Eye Research Institute, San Francisco, CA.
Purpose: To demonstrate differences between diabetic patients without retinopathy
and non-diabetic patients under mesopic and photopic conditions using a simple
rapid computerized test for foveal contrast sensitivity (CS).
Methods: Nineteen eyes (n=10 patients with type 2 diabetes) without any signs of
diabetic retinopathy were included. Ten additional eyes (n=5 non diabetic patients)
served as controls. All the eyes had a visual acuity of 20/25 or better. All the patients
underwent a careful ophthalmologic examination including ETDRS chart visual
acuity, color photographs and optical coherence tomography (OCT). Patients with
cataract were excluded. Photopic and mesopic contrast sensitivity was tested using a
computerized psychophysical static method involving four forced-choice procedures.
The targets were Gabor patches with spatial frequencies of 3-12 cycles per degree (cpd).
The mesopic testing was conducted in a completely darkened room; the monitor was
covered with a neutral density filter, allowing luminance of only 0.9 cd/m 2. Before
participation, all subjects provided written informed consent in accordance to the
protocol approved by the Helsinki committee.
Results: The average age was similar in both groups - 59.1 years in the diabetic group
(range 54-73) vs 62.6 years in the control group (range 58-66). The average duration
of diabetes was 16 years (range 6-26).The average visual acuity was 0.05 logMAR and
0.02 in the diabetic and control groups respectively. OCT was diagnosed as normal
in both groups.
Foveal CS was similar under photopic conditions in both groups. Significantly lower
CS was found in diabetic patients under mesopic conditions at the spatial frequency of
3 cycles per degree (cpd) (p<0.012). At higher spatial frequencies the mesopic contrast
sensitivities was very low in both groups and without a significant difference.
Conclusions: Mesopic foveal CS is impaired in diabetic patients despite good visual
acuity, normal fundus examination and normal OCT. It is suggested that early central
visual function impairment may occur in diabetic patients before the appearance of
retinopathy. Further research is necessary to establish the role of computerized CS
testing in the screening and monitoring of diabetes.
CR: G. Katz, None; G. Treister, None; H. Levkovitch-Verbin, None; M. Belkin,
None; J. Ilany, None; U. Polat, None.
Support: Supported in part by the Claire and Amedee Maratier Institute, Tel-Aviv
University
Purpose: To evaluate contrast sensitivity (CS) responses mediated by magnocelular
(MC) and parvocellular (PC) systems in type 2 diabetics with normal fundus (NDR)
and with non-proliferative retinopathy (DR).
Methods: Pokorny & Smith’s (1997) steady/pulsed pedestal paradigms (SP/PP) were
used to assess MC- and PC-dominated responses, respectively, in 27 NDR (13M; 56 ±11
yrs old; time of disease = 5 ± 4 yrs); 21 DR (6M; 58 ± 10 yrs old; time of disease = 9 ± 6
yrs) and 28 controls (CTRL) (11M, 44 ± 10 yrs old). The test consists of the presentation
of an adaptation pedestal on which a luminance increment must be detected by the
subject. Thresholds were measured with pedestals at 7, 12 and 19 cd/m 2, and flash
durations of 17 and 133 ms. Visual stimuli were generated by a 15-bit graphic board
VSG 2/5 (CRS, Ltd) and presented on a Trinitron 21’ monitor GDM F500T9 (Sony).
Tests were performed monocularly in a darkened room. For assessment of temporal
features, we estimated critical durations (Tc) for each data set using the thresholds
from two stimulus durations (Krauskopf & Mollon, 1971).
Results: Both DR and NDR patients had significant reduction in CS in both SP and PP
paradigms in relation to CTRL (Kruskal-Wallis test, p<0.0)1, implying losses in both
MC and PC pathways. Responses from NDR and DR patients were elevated more as
pedestal luminance increased. Tc’s were not significantly different from CTRL for
either patient group, for either paradigm.
Conclusions: Overall, DR and NDR diabetics had significant reduction of CS in both
SP and PP paradigms, consistent with no preferential loss in either of the parallel
processing pathways. The decrease in CS with luminance in both groups suggests
impaired gain control system even in the absence of retinopathy. Our tests reveal no
evidence of compromised processing speed in either diabetic group.
CR: M. Gualtieri, None; M. Bandeira, None; F.M. Damico, None; A.L.A. Moura,
None; R.D. Hamer, None; D.F. Ventura, None.
Support: FAPESP, CAPES, CNPq, FINEP IBN-Net
2897 - A100
Magno and Parvocellular Pathways Responses in Patients With Multiple
Sclerosis
2898 - A101
Spatial Resolution on the Tongue as Applied to a Prosthetic BrainPort ® Vision
Device
A.L.A. Moura1A, M. Gualtieri1A, R.A.A. Teixeira1A, M.L. Bandeira1A, D. Callegaro1B, R.D.
Hamer1A,2, D.F. Ventura1A. ADepartment of Psychology, BNeurology Section, Clinics
Hospital, 1Universidade de Sao Paulo, Sao Paulo, Brazil; 2Smith-Kettlewell Eye
Research Institute, San Francisco, CA.
A. Arnoldussen, B. Besta, A. Ferber, E. Fisher, R. Hogle, S. Lederer, M. Rosing. Wicab,
Inc., Middleton, WI.
Purpose: To assess magnocellular (M) and parvocellular (P) responses in patients
with multiple sclerosis (MS), with and without history of optic neuritis.
Methods: We evaluated 21 patients with diagnosis of MS (16F; 5M; mean age =
34.8±10.34 years). All patients had visual acuity between 0 and 0.1 logMAR and
had no significant findings in an ophthalmologic exam performed at the time of
testing. Nine patients had optic neuritis episodes between 1 and 26 years prior to
the test. We used Pokorny & Smith’s (1997) Steady-Pedestal (SP) and Pulsed-Pedestal
(PP) paradigms as adapted recently by Gualtieri et al. (2006). For both paradigms, a
pedestal of four 10x10 squares was presented on a 12 cd/m 2 surround, and observers
had to detect a brief (17 or 133 ms) increment of luminance of one of these (the test
square, TS). For the PP paradigm, the pedestal was pulsed along with the TS, which
was modulated relative to the other 3 squares. For the SP paradigm, the pedestal
was on continuously, and only the TS was modulated. Pedestal luminances were 7,
12 and 19 cd/m 2. Thresholds were measured using a double-interleaved staircase, in
4-alternative forced-choice task. Prior research indicates that the SP and PP paradigms
reflect M- and P-dominated responses, respectively.
Results: For the PP paradigm, patients’ contrast thresholds were significantly elevated
at all 3 pedestal levels for the 133 ms TS duration. For the 17 ms TS, their thresholds
were elevated for the 12 and 19 cd/m 2 pedestals (Mann-Whitney U-test, p < 0.01).
For the SP paradigm, patient’s thresholds were significantly elevated for both test
durations, but only for the 12 cd/m 2 pedestal. There were no significant differences
between thresholds from MS patients with and without a previous neuritis episode.
Threshold data did not correlate with time of disease.
Conclusions: Consistent with some prior reports (Caruana et al, 2000), the MS patients
evaluated in this study had reduced contrast sensitivity mainly in the PP paradigm,
suggesting preferential loss in the P pathway.
CR: A.L.A. Moura, None; M. Gualtieri, None; R.A.A. Teixeira, None; M.L. Bandeira,
None; D. Callegaro, None; R.D. Hamer, None; D.F. Ventura, None.
Support: FAPESP, CNPQ, CAPES
Purpose: For those who are blind, the BrainPort® Vision Device enables perception
of visual information using the tongue as a substitute for the eye. Users form a spatial
reference with just a few hours of training, mapping cutaneous information on the tongue
to their environment. In order to evaluate the potential visual “acuity” of the developing
BrainPort Vision system, we designed an experiment to determine spatial discrimination
on the tongue using electro-cutaneous stimulation.
Methods: Sixteen sighted subjects (10 men; 6 women) participated, ranging in age from
18-39 years old (mean 24.5yrs). Subjects were recruited from the Madison, WI area. All
subjects gave informed consent with a study protocol approved by the New England IRB.
A linear electro-cutaneous stimulation array was specially fabricated with 10 electrodes
(tactors) 169 micrometers (µ) diameter spaced 254µ apart. Half of the trials contained
only one stimulating tactor, while the other half contained two firing tactors of a fixed
condition distance: 254µ, 580µ, 762µ, 1016µ and 1261µ center-to-center distance. Subjects
were instructed to press one button if they felt one stimulus and another button if they
felt two stimuli. They were encouraged to use the tip of their tongue and to move and/
or explore the stimulation with any part of the tongue in order to respond maximally.
There was no response time limit allowing subjects to explore the stimulus with any part
of the tongue they felt gave them the best information.
Results: Data points were translated into a d-prime score for each spacing condition
and subject. Threshold discrimination was a priori defined as a d-prime score greater
than 1. As a group, performance exceeded d-prime>1 when tactors were spaced 762µ.
A one way ANOVA revealed a significant main effect for tactor spacing (F(4,60)=4.466,
p<.005). As the tactor spacing increased, performance improved. Twelve percent of tested
subjects scored above threshold individually in the most closely spaced 254µ condition.
While the group average threshold is 762µ, there are individuals who have better than
average discrimination abilities. This may suggest that an individual’s actual limit may
be better than 254µ spacing.
Conclusions: These results suggest that without extensive training, average spatial
perception on the tongue is 762µ or better. This allows us to optimize the size and
spacing of tactors coupled with appropriate optics when designing our prosthetic vision
substitution system to report comparative visual acuity measures.
CR: A. Arnoldussen, Wicab, Inc., F; B. Besta, Wicab, Inc., F; A. Ferber, Wicab, Inc., F;
E. Fisher, Wicab, Inc., F; R. Hogle, Wicab, Inc., F; S. Lederer, Wicab, Inc., F; M. Rosing,
Wicab, Inc., F.
Support: DARPA Contract FA8650-07-C-7705; NIH Grant EY014105-03
2895-2898
Tuesday, April 29, 3:00 PM - 4:45 PM Room 305 Paper Session Program Number Range: 3246-3252
372. Color Vision: Structure and Function Organizing Section: VI Contributing Section: BI, VN
3246 - 3:00PM
Insights Into Mechanisms Regulating Cone Opsin Expression From S-opsin
“Knock-out” Mice
3247 - 3:15PM
Origin of the Blue-Sensitive Visual Pigment in Primates: Site 86 Revisited
L.S. Carvalho1, W.L. Davies1, P.R. Robinson2, J.K. Bowmaker1, D.M. Hunt1. 1Institute of
Ophthalmology, University College London, London, United Kingdom; 2Biological
Sciences, University of Maryland Baltimore County, Baltimore, MD.
L.L. Daniele1A, R.K. Chance1B, J. Wang1A, E.N. Pugh, Jr.1A. AOphthalmology,
B
Neuroscience Graduate Group, 1University of Pennsylvania, Philadelphia, PA.
Purpose: To test the effects of disruption of the mouse Opn1sw (S-opsin) gene on cone
photoreceptor function and cone opsin expression.
Methods: In the process of creating a “knock-in” mouse with a targeted point mutation
a NeoR cassette with a stop codon was introduced into the Opn1sw gene locus at intron
3-4. Oriented retina whole mounts and cryosections were labeled with immunosera
to detect Arrestin-4 (mCarr), S-opsin and M-opsin. Cone b-waves were recorded
from Opn1sw Neo/Neo and WT mice using electroretinography. Single cell recordings of
Opn1sw Neo/Neo cones from known retinal locations were made to investigate spectral
sensitivity. Total RNA was isolated from eyes of Opn1sw Neo/Neo and WT mice and
subjected to quantitative real-time RT-PCR (qRT-PCR) analysis to investigate changes
in expression of cone opsins.
Results: No S-opsin positive cells were detected in retinas of Opn1sw Neo/Neo mice.
However cone number and morphology appeared unaltered. Opn1swNeo/Neo mouse cone
b-wave sensitivity peaked at 510 nm with a ratio of sensitivity at 360 nm relative to 510
nm (S360/S510) of 0.4. In contrast, WT cone b-wave sensitivity peaks at 360 nm having
a secondary peak at 510 nm with S360/S510 = 4.6. Interestingly, absolute cone b-wave
sensitivity at 510 nm increased in Opn1sw Neo/Neo mice by ~ 2-fold. S-opsin transcript was
~ 5-fold more abundant than M-opsin transcript in WT retinas, consistent with ERG
spectral sensitivities. In Opn1sw Neo/Neo mice transcript levels of S-opsin (exon 4-5 probe)
relative to rhodopsin were reduced by ~1000-fold compared with WT, while M-opsin
transcript levels relative to rhodopsin were not significantly different. The spectral
sensitivity of single cones of Opn1sw Neo/Neo mice from the mid-ventral retina, the sector
with the highest expression of S-opsin in WT retinas, peaked at ~510 nm, consistent
with expression of M-opsin as the sole visual pigment. Conclusions: Opn1sw Neo/Neo
mice express no functional cone S-opsin, yet our data indicate no decrease in the total
number of cones. The two-fold increase in ERG b-wave sensitivity at 510 nm suggests
a possible increase in the levels of M-opsin. Increased M-opsin in Opn1sw Neo/Neo mice
suggests a mechanism that operates to conserve a fixed concentration of opsin in cone
photoreceptors. Given the negative qRT-PCR results, altered transcription is not a
plausible mechanism. Other mechanisms such as increased translation or increased
trafficking of M-opsin to outer segments are under investigation.
CR: L.L. Daniele, None; R.K. Chance, None; J. Wang, None; E.N. Pugh, None.
Support: EY02660, EY016453, RPB Foundation
Purpose: The primate group can be divided into two major informal groups, the
Prosimians and the Simians. The Prosimian group includes the lemurs, tarsiers,
bushbabies and lorises. The Simian group is divided into the Platyrrhini or New
World monkeys and the Catarrhini or Old World monkeys including humans and
great apes. The photopic visual system in New and Old World monkeys is based on
separate M and L pigments arising from either a duplication or a polymorphism of the
longwave-sensitive (LWS) opsin gene. These pigments are combined with the S pigment
derived from the shortwave-sensitive type I (SWS1) opsin gene to give trichromatic
colour vision. Trichromacy may also be present in some prosimian species. The loss
of a functional SWS1 gene has occurred in some primate species, notably amongst the
nocturnal prosimians. The peak sensitivities of SWS1 pigments range from the violet
(385-445 nm) to the UV (355-365 nm) and the molecular mechanism underlying this
shift is determined by the residues present in the vicinity of the retinal binding pocket,
mainly at site 86. In mammals, Phe86 alone is capable of conferring UV sensitivity while
violet pigments can have different residues at this site. In higher primates, the SWS1
tuning mechanism appears more complicated with up to 8 simultaneous substitutions
required to generate a violet pigment. The objective of this study was to analyse the
tuning mechanisms of the SWS1 pigment in Prosimians and examine the effects of
the only naturally-occurring Phe86 residue in the pigment of a primate.
Methods: Coding sequences were amplified from gDNA using a recently published
SPLICE technique devised in our lab and cloned into an expression vector. Mutant
opsins were generated by site-directed mutagenesis. Wild type and mutant SWS1
coding sequences were transiently transfected into HEK 293T cells, the resulting
opsins were purified by immunoaffinity chromatography and reconstituted with
11-cis-retinal.
Results: In vitro expression of recombinant opsins and spectral analysis of the resultant
pigments confirms the violet-sensitivity of the SWS1 pigments in three prosimian
species with different residues at site 86. These include the pigment in the Aye-aye,
the only primate SWS1 pigment that has Phe86.
Conclusions: The results provide evidence that an alternative residue may play a major
role in the tuning of SWS1 pigments in primates and has enabled a re-evaluation of
the evolution of violet sensitivity within the primate group as a whole.
CR: L.S. Carvalho, None; W.L. Davies, None; P.R. Robinson, None; J.K. Bowmaker,
None; D.M. Hunt, None.
Support: Leverhulme Trust UK Grant F/07 134/AX
3248 - 3:30PM
Imaging the Functional Response of Cones to Color Stimuli
3249 - 3:45PM
Color-Opponent Ganglion Cells in Guinea Pig Retina (S+/M- and S-/M+) CoStratify in the ON Stratum of the IPL
R.S. Jonnal, B. Cense, W. Gao, J.M. Brown, C. Zhu, D.T. Miller. Optometry, Indiana
Purpose: Cone photoreceptors, under certain illumination conditions, undergo fast
stimulus-evoked changes in reflectance (“scintillation”) at near infrared wavelengths
[1]. While scintillation has been characterized for red stimuli (specifically 670 nm), other
color stimuli have not been considered. The dependence of scintillation duration and
pattern on stimulus color may provide additional insight into the function of cones,
especially with regard to their spectral properties.
Methods: Videos of the cone mosaic at 2.5 degrees eccentricity were acquired at 192
Hz over 2 s intervals using an adaptive optics retina camera. The imaging source
was a near-infrared laser diode (λ = 915 nm, Δλ = 3 nm). Stimuli of various color,
duration, and illuminance were delivered to the retina during the video acquisition.
Registration of video images and inter-registration of videos allowed the comparison
of scintillation for the same cone under different stimulus conditions.
Results: Cones were found to scintillate at almost all stimulus wavelengths considered,
but the number of cones that did and the duration and magnitude of the scintillation
varied with the stimulus color. Some cones, for example, responded strongly to a red
(670 nm) stimulus and weakly to a blue (<450 nm) stimulus, while others exhibited
a reverse behavior (see Fig. 1).
Conclusions: Cones scintillate differently depending on the stimulus color.
[1] R. S. Jonnal et al., Opt. Express 15, pp. 16141-16160 (2007).
Figure 1. Reflectance of two representative cones as a function of time after delivery
of red and blue stimuli.
CR: R.S. Jonnal, None; B. Cense, None; W. Gao, None; J.M. Brown, None; C. Zhu,
None; D.T. Miller, None.
Support: NEI Grant 1R01EY018339, NEI Grant 5R01EY014743, NSF Science and
Technology Center for Adaptive Optics No. AST-9876783
L. Yin1A, R.G. Smith1A, P. Sterling1A, D.H. Brainard1B. ANeuroscience, BPsychology,
1
University of Pennsylvania, Philadelphia, PA.
Purpose: Most mammals have short-wavelength sensitive (S) cones and one or two
types of middle/long-wavelength (M/L) sensitive cones. In primate, some ganglion
cell types combine inputs from S cones antagonistically with those from M/L cones.
In dichromatic mammals, no direct evidence links the morphology of a ganglion cell
with physiological S/M opponency. We identified color-opponent ganglion cells in
guinea pig and then studied their morphology. Because guinea pig retina exhibits
a dual gradient in S/M opsin expression across the retina, we also studied whether
S/M opponency varies with this gradient.
Methods: We recorded spikes from ganglion cells with extracellular loose patch
electrodes from in vitro whole-mount albino guinea pig retina. Chromatic properties
were characterized by responses to (a) spots produced by mixtures of two primary
lights and (b) flashed monochromatic spots. After recording, we stained the cell with
Lucifer yellow and quantified its dendritic morphology.
Results: In superior retina, we found cells with strong S+/M- and S-/M+ opponency.
In inferior retina, we found cells with weak S+/M- opponency. The S/M opponent
cells in superior retina (n = 4) had well-balanced M and S weights, while those in
inferior retina (n = 2) had unbalanced M and S weights, with the M weights being
much weaker. All of the opponent cells that we identified were monostratified, with
dendritic arbors in the ON sublamina of the inner plexiform layer. Two bistratified
cells studied were non-opponent.
Conclusions: The decline in S/M opponency we found in inferior retina is consistent
with the dual gradient, suggesting that retinal circuitry in inferior retina does not
enhance S/M opponency by selectively amplifying the M-opsin input to S/M opponent
ganglion cells.
CR: L. Yin, None; R.G. Smith, None; P. Sterling, None; D.H. Brainard, None.
Support: NEI grants EY10016, EY08124, EY016607 and P30 EY001583
3246-3249
Tuesday, April 29, 3:00 PM - 4:45 PM Room 305 Paper Session Program Number Range: 3246-3252
372. Color Vision: Structure and Function Organizing Section: VI Contributing Section: BI, VN
3250 - 4:00PM
Primate Blue Cones Receive Rod Input
3251 - 4:15PM
Probing Neural Circuitry for Blue-Yellow Color Vision Using High Resolution
Functional Magnetic Resonance Imaging
J. Verweij1, P.H. Li1, O. Packer2, D.M. Dacey2, J.L. Schnapf 1. 1Ophthalmology,
University of California, San Francisco, CA; 2Biological Structure, University of
Washington, Seattle, WA.
M.C. Mauck, A. Salzwedel, J. Kuchenbecker, C. Pawela, J. Garcia, J. Hyde, A. Hudetz, T.B.
Connor, Jr., J. Neitz, M. Neitz. Medical College of Wisconsin, Milwaukee, WI.
Purpose: Rod stimulation evokes changes in human color perception. Direct rod
input to cones through gap junctions could contribute to this effect. In primate retina,
rods appear to make gap junctions with all 3 cone types, and rod signals transmitted
through gap junctions have been measured in red and green cones. Are rod signals
also transmitted to blue cones?
Methods: Blue cones in isolated macaque retina were targeted for whole-cell recording
based on the depth and diameter of their inner segments. Identification was confirmed
from measurements of spectral sensitivity.
Results: The current response in a blue cone to a flash of light consists of 3 components:
1) a fast outward component with an action spectrum matching blue-opsin absorption,
2) a fast inward calcium current caused by feedback from horizontal cells, driven by
red and green cones and 3) a slow outward component with the temporal kinetics
of a rod response. This putative rod signal had the action spectrum of rhodopsin
and could be evoked by rod isolating stimuli. It was selectively eliminated by rodadapting backgrounds.
Conclusions: Blue cones receive rod input through rod-cone gap junctions.
Quantification of the relative strength of rod input to red, green and blue cones
and further modeling can determine the contribution of this pathway to color
perception.
CR: J. Verweij, None; P.H. Li, None; O. Packer, None; D.M. Dacey, None; J.L. Schnapf,
None.
Support: NIH Grants EY007642 and EY06678, RR00166, and grants from That Man
May See, and Research to Prevent Blindness
Purpose: There are no models in which to probe mechanisms of human red-green color
vision except nonhuman primates. However, other mammals can be studied to understand
blue-yellow color vision circuitry. Rats, which fit in the small bore of an ultra high field
strength MRI scanner have subcortical brain structures of a favorable size relative to
neocortex which together with the scanner’s high spatial resolution (ca. 0.1 X 0.1 mm
voxels; in 1 mm slices) allows visualization of color vision circuit activity throughout the
CNS. A distinct pathway assumed to be a substrate for blue-yellow color vision has been
traced in primates from depolarizing S-cone bipolar cells to small bistratified ganglion
cells to LGN koniocellular layers to VI layers 2/3. Blood oxygenation level dependent
(BOLD) signals were obtained in response to heterochromatically modulated S-(λmax =
360 nm) and M-cone isolating stimuli from rats in which the S-cone bipolar pathway was
blocked in one hemisphere via monocular injection of 2-amino-4-phosphonobutyrate
(APB); this also blocked input to “S-OFF” melanopsin ganglion cells, the other well
characterized cell type carrying S cone input.
Methods: Lights were delivered to anesthetized rats in a 9.4T MRI system through fiber
optics to provide full field, diffuse illumination binocularly. 5 rats received an intravitreal
injection of 2-APB monocularly.
Results: In the hemisphere receiving input from the untreated eye, S-cone stimuli
activated the dorsal and ventral lateral geniculate nucleus (dLGN & vLGN). As expected,
subcortical BOLD signals in response to S-cone stimuli were greatly reduced on the APB
treated side. The absence of signal to the vLGN is presumably the result of melanopsin
ganglion cell blockade, while the diminished dLGN response reflects the obstruction
of the S-cone bipolar pathway. Stunningly, in contrast to the pattern of subcortical
activation, the BOLD signals were dramatically enhanced in neocortex in response to
S-cone isolating stimuli presented to the APB treated eye.
Conclusions: The pathway which has been assumed to be responsible for blue-yellow color
vision actually undergoes a sign-reversal at the level of the cortex damping responses to
S-cone stimuli. Excitatory S-cone signals must be derived from a pathway that originates
from hyperpolarizing bipolar cells. Thus, two S-cone pathways one originating from
hyperpolarizing and the other from depolarizing bipolar cells are likely to provide the
antagonistic components of S+/S- receptive fields proposed from psychophysics.
CR: M.C. Mauck, None; A. Salzwedel, None; J. Kuchenbecker, None; C. Pawela,
None; J. Garcia, None; J. Hyde, None; A. Hudetz, None; T.B. Connor, None; J. Neitz,
None; M. Neitz, None.
Support: NIH Grants R03EY014056, R01EY016861, R01EY11123, T32EY014537, EY01981,
the Harry J. Heeb Foundation, and RPB.
3252 - 4:30PM
Colorblindness Cure: Gene Therapy Confers a New Sensation
K. Mancuso1, M. Neitz1, W.W. Hauswirth2A, Q. Li2B, T.B. Connor, Jr.1, J. Kuchenbecker1,
M.C. Mauck1, J. Neitz1. 1Ophthalmology, Medical College of Wisconsin, Milwaukee,
WI; ADepartment of Ophthalmology and Powell Gene Therapy Center,
B
Department of Ophthalmology, 2University of Florida, Gainesville, FL.
Purpose: Among members of the primate species, Saimiri sciureus (squirrel monkey),
a subset of females are trichromatic while males have dichromatic color vision. The
dichromats are an ideal model of red-green colorblindness in humans that results from
the absence of either the long- (L) or middle- (M) wavelength-sensitive photopigment
genes. While normal trichromats have four main hue percepts - red, green, blue, and
yellow, - dichromats can discriminate blues and yellows from gray, but lack percepts
of red and green. We asked if the addition of a third photopigment would allow
dichromatic monkeys to become fully trichromatic, in order to answer whether a single
genetic change in the retina can result in a new sensory capacity in adults.
Methods: A recombinant adeno-associated virus vector containing an L-opsin gene
was injected subretinally. The goal was to exploit the capricious nature of viral infection
to transduce only a subset of cones, producing a retinal region with two randomlyinterspersed cone types absorbing in the middle-to-long wavelengths. To evaluate
transgene expression at the level of the retina, we developed an LED-based wide-field
color multifocal electroretinogram (ERG) apparatus. The effects of the treatment on
color vision behavior were measured using a computerized color vision test, the
Cambridge Colour Test, which was adapted for use with the monkeys.
Results: Before treatment, the monkeys’ discrimination was tested for 16 different
hues. Their behavior was highly reliable and they always failed to make “red-green”
discriminations, as predicted from their known cone complement. Following gene
therapy, successful L-opsin expression and modified cone physiology were readily
detected with the color multifocal ERG as an increase in sensitivity to long-wavelength
light. In turn, comparisons of pre- and post-therapy color vision test results indicated
that the animals also gained a new sensory capacity, red-green color vision, in response
to gene therapy.
Conclusions: Conventional wisdom has held that “critical periods” exist for the
development of new visual capacities, raising the concern that treating adults with
congenital conditions could be impossible. The successful treatment of adult monkeys
that had a color vision defect from birth is encouraging for the possibility of using gene
therapy to treat a variety of inherited vision disorders that involve cone photoreceptors
in humans.
CR: K. Mancuso, None; M. Neitz, None; W.W. Hauswirth, AGTC Inc., C; Q. Li,
None; T.B. Connor, None; J. Kuchenbecker, None; M.C. Mauck, None; J. Neitz,
None.
Support: NIH Grants R03EY014056, R01EY016861, R01EY11123, T32EY014537, EY01981,
the Harry J. Heeb Foundation, and RPB.
3250-3252
Tuesday, April 29, 3:00 PM - 4:45 PM Hall B/C Poster Session Program Number/Board # Range: 3319-3330 / A102-A113
381. Peripheral Optics and Peripheral Vision Organizing Section: VI
3319 - A102
Evaluating the Influence of Oval Pupils on the Fitting of Zernike Polynomials
D.A. Berntsen, D.O. Mutti, K. Zadnik. College of Optometry, Ohio State University,
Columbus, OH.
Purpose: Because most aberrometry software only fits circles with diameter equal to
the minor axis of an oval pupil, additional processing is needed to utilize all data from
peripheral measurements. We evaluate the effect on the central Zernike polynomial
fit of including missing data and data outside the circular diameter of the oval pupil
minor axis.
Methods: A peripheral measurement 30º temporal on the retina from the line of sight was
made on the dilated right eye of thirty subjects using the Complete Ophthalmic Analysis
System (COAS; AMO WaveFront Sciences). Subjects ranged in age from 23 to 45 years
(mean ± SD = 31 ± 6.7 years), and central spherical equivalent refractive error ranged
from +0.63 to -8.41 D (mean ± SD = -2.63 D ± 2.05 D). A 6-mm analysis diameter within
the minor axis of the oval pupil was used to analyze the data with the COAS software.
Complete Light Analysis System (CLAS-2D; AMO WaveFront Sciences) software was
then used to draw an analysis circle with diameter equal to the major axis of the oval
pupil, which includes missing data outside the oval pupil. Using methods described
by Schwiegerling (2002), CLAS-2D Zernike coefficients through 6th order were scaled
down to a 6-mm pupil diameter and compared to 6-mm COAS Zernike results. Paired
t-tests were used to compare the 6-mm Zernike coefficients and RMS errors calculated
by these two methods.
Results: The mean differences and 95% limits of agreement (LoA) are shown in Table 1
for total RMS (2nd to 6th order), higher-order RMS (3rd to 6th order), Z(3,1), Z(3,-1), and
Z(4,0). Although three of the differences calculated were significantly different than
zero, the mean differences are not clinically meaningful. For a 6-mm pupil, the largest
significant mean difference and LoA (for total RMS error) were equivalent to 0.03 D and
±0.11 D of spherical defocus, respectively.
3320 - A103
Modal Estimation of Wavefront Over Elliptical Pupil From Hartmann Shack
Wavefront Sensor Estimated Gradients
X. Wei, L. Thibos. Vision Science, Indiana University, Bloomington, IN.
Purpose: Peripheral vision and off axis aberration not only play an important role
in daily visual tasks but may also influence eye growth and refractive development.
Measuring the off-axis optical quality of the eye with a Hartmann Shack wavefront
sensor requires methods for reconstructing wavefront from the gradient data defined
within an elliptical domain.
Methods: In addition to two published reconstruction methods (Atchison et al, JOSA
19(11) 2180; Lundström et al, J Biomed Opt 10(3) 034002) based on least-squares fitting
of wavefront slope to spatial derivatives of Zernike polynomials, two new methods
(inscribed methods and boundary methods) based on the Fourier integral theorem
were derived rigorously and implemented in Matlab.
Results: Wavefronts obtained from a wide angle schematic eye via ray tracing in
Zemax were used as test cases to validate the theoretical predictions of the four
methods. The RMS of reconstruction error was less than 1% of RMS of the tested
wavefront for all four methods.
Conclusions: The four proposed methods based on least-squares fitting and Fourier
integration were successfully implemented in Matlab to solve the general wavefront
reconstruction problem from the gradients data defined over an elliptical pupil. The
validation of the four methods on wavefronts obtained from a wide angle schematic
eye indicates their numerical stability during objective Hartmann Shack Wavefront
Sensor measurements of human eye.
CR: X. Wei, None; L. Thibos, None.
Support: NIH R01-EY05109
Table 1: Mean differences between COAS and CLAS-2D analyses in microns (COAS minus CLAS-2D)
mean ± SD
p-value
95% LoA
Total RMS
0.035 ± 0.072
0.01
-0.110 to 0.179
Higher-Order RMS
-0.012 ± 0.027
0.02
-0.066 to 0.043
Horizontal Coma: Z(3,1)
0.013 ± 0.032
0.04
-0.050 to 0.076
Vertical Coma: Z(3,-1)
-0.018 ± 0.052
0.07
-0.121 to 0.085
Spherical Ab: Z(4,0)
-0.010 ± 0.031
0.09
-0.072 to 0.052
Conclusions: Drawing an analysis circle equal to the major axis of an oval pupil, which
includes missing data and data outside the diameter of the minor axis of the oval,
does not have any substantial influence on the wavefront fit within the minor axis
diameter. Additional work is necessary to validate the wavefront fit outside the smaller
diameter.
CR: D.A. Berntsen, None; D.O. Mutti, None; K. Zadnik, None.
Support: NIH Grants: K12-EY015447 & T32-EY013359 and an AOF Presidents Circle
Ezell Fellowship (DAB)
3321 - A104
Wavefront Aberrations in Peripheral Vision for Avian Eye
3322 - A105
Off-Axis Monochromatic Aberrations in a Wide-Angle Model Eye
Y. Garcia Sanchez, C. Torti, B. Hermann, J.T. Erichsen, W. Drexler. Optometry, Cardiff
University, Cardiff, United Kingdom.
J. Shen, L. Thibos. School of Optometry, Indiana University, Bloomington, IN.
Purpose: This study investigates the hypothesis that the off-axis vision of avian eyes
is adapted to their environment. In the preliminary phase of this project, aberrations
in human peripheral vision were evaluated for comparison with the findings in the
animal study.
Pigeons are highly visual and possess a very specialized retina with adaptations
for peripheral viewing. As a result, they are a suitable animal model to work with in
the field of vision science. The eyes of pigeons are laterally positioned, providing a
panoramic view of the world. Most birds also have a secondary specialization of the
temporal retina for frontal viewing
Methods: A Hartmann-Shack wavefront sensor (HSWFS) has been developed to
measure the ocular aberrations of the eye. The birds were anesthetized during the
measurements and the pupil was dilated to allow access to peripheral retinal locations.
Twenty measurements were made at each position and each measurement was based
on an average of ten frames.
Results: The present results (see Fig 1) indicate that the amount of aberrations
increases with eccentricity from visual axis in the avian eye. For the frontal visual field
(temporal retina) in the avian eye, the value of the Zernike coefficients corresponding
to astigmatism are lower than on axis and in the posterior field (nasal retina).
Conclusion: This research provides important information about the underlying
mechanisms by which the quality of the pigeon’s vision is maintained away from the
eye’s central axis (e.g. frontal vision). Our findings with the HSWFS are consistent
with previous retinoscopic studies which have indicated that the pigeon eye is largely
corrected for off-axis aberrations, thereby providing good optical correction for
peripheral vision. This is an important adaptation given the presence of the secondary
temporal fovea in the avian eye.
Figure 1. - Representation of the wavefront aberration for avian eye for three different
positions from left to right: posterior field, frontal field and optical axis. The wavefront
maps were obtained from an average of 20 wavefront measurements .
CR: Y. Garcia Sanchez, None; C. Torti, None; B. Hermann, None; J.T. Erichsen,
None; W. Drexler, Carl Zeiss Meditec, C.
Support: Cardiff University
Purpose: To evaluate the use of a clinical wavefront aberrometer (COAS, Wavefront
Sciences, Inc.) for off-axis measurements of ocular wavefront aberrations.
Methods: A single-surface, emmetropic model-eye was constructed from a planoconvex lens cemented to a flat milled onto an acrylic sphere (25.4 mm dia). The outer
surface of the sphere was sandblasted and tinted to provide a diffusely reflecting
surface that models the human fundus. A Coddington pupil (7mm diameter, 3.5mm
posterior to the lens apex) was the limiting aperture for light reflected from the
model fundus. Trial lenses corrected refractive errors present in the peripheral field.
Wavefront phase were reconstructed from slope measurements over a circular domain
circumscribed around the elliptical entrance pupil.
Results: Up to 30° of eccentricity, the wavefront sensor recorded slope measurements
over the entire entrance pupil. Beyond 35º, the irradiance declined rapidly along the
minor axis of the elliptical pupil, possibly due to the range-limiting-aperture in COAS
that blocks highly aberrated rays. The change of RMS wavefront error over a circular
mask from 0° to 30° of eccentricity was small for 2nd- to 6th- Zernike orders. However,
RMS of all of Zernike orders increased dramatically, as did measurement variance,
beyond 30º of field angle, again indicating unreliable measurements at large field
angles. The model eye became increasingly myopic and astigmatic off-axis and the
higher order aberrations of 3rd-order coma and 5th-order coma showed also increased
off-axis. All of these changes were highly correlated.
Conclusions: Measurements of off-axis wavefront aberrations of a model eye from
0° to 30° of eccentricity are possible with the COAS clinical wavefront aberrometer
and auxiliary lenses to correct astigmatism. Care is required to ensure that the entire
entrance pupil is sampled by the wavefront sensor and that wavefront reconstruction
is performed over the entire elliptical pupil.
CR: J. Shen, None; L. Thibos, None.
Support: NIH Grant
3319-3322
3323 - A106
Study of Ocular Aberrations as a Function of the Field Angle Within Young
Population
3324 - A107
Compensation of Off-Axis Aberrations, Especially Coma, in the Human Eye
M. Nowakowski, A.V. Goncharov, C. Dainty. Dept. of Experimental Physics, Applied
Optics Group, NUIG, Galway, Ireland.
Purpose: Adaptive Optics (AO) techniques have recently been used to improve
retinal imaging over a small field (about 1 degree) that is closely related to the probing
direction of a wavefront sensor. The purpose of this study was to measure ocular
aberrations within central 10 deg visual field in order to establish how one could correct
ocular aberrations over larger field than that achievable with current AO systems.
Methods: Fifteen young and healthy subjects were studied with an ocular aberrometer
that incorporates the Shack Hartmann wavefront sensor, pupil-tracking system, Badal
adjustment stage, fixation target and laser-diode probing beam. The aberrometer was
used to measure ocular aberrations in the pupil plane at 0, 3 and 5 deg from the field
center in the horizontal and vertical meridians on both sides. Two measurements
were taken for each direction to minimize the optical effect of the tear film. The
aberrometer demonstrated high repeatability of measurements for an artificial eye
used for calibration.
Results: Measurements of ocular aberrations as a function of the field angle for
6-mm pupil revealed several groups of eyes with different aberration functions.
Furthermore, measurements clearly showed that the dominant aberration within
the central field is astigmatism. Numerical analysis was performed as an attempt to
identify those aberrations, which do not display large variation across the visual field.
These are spherical aberration and coma, and therefore they can be easily corrected
by a standard AO system.
Conclusions: The results show that for the young healthy population, the main
contributor to the total amount of ocular aberrations is astigmatism, which varies
across the central visual field. In light of this, improving AO-assisted retinal imaging
systems requires additional optics to compensate for the residual astigmatism,
especially in a wide-field operation mode.
CR: M. Nowakowski, None; A.V. Goncharov, None; C. Dainty, None.
Support: SFI/01/PI.2/B039C
Y. Hirohara1,2, T. Tanabe1, T. Fujikado2, H.C. Howland 3, T. Mihashi1,2. 1Research Institute,
Optics Lab., Topcon Corp., Tokyo, Japan; 2Department of Applied Visual Science,
Osaka University Graduate School of Medicine, Osaka, Japan; 3Neurobiology &
Behavior, Cornell University, Ithaca, NY.
Purpose: We investigated the off-axis wavefront aberrations (WAs) of the whole eye
and the cornea of the human eye.
Methods: Ten normal right eyes of ten subjects were included in the study. Ocular
and corneal WAs were analyzed with Hartmann-Shack wavefront sensor and with
a corneal topographic analyzer (Wavefront analyzer, Topcon Corp, Tokyo, Japan).
Subjects fixated five different points on the inner fixation target (center, and 4.5 degrees
off-axis at the top, bottom, right-side, and left-side of the target plane). WFAs were
analyzed using normalized Zernike polynomials up to the fourth order defined over
a 4-mm diameter area in the center of the pupil. The coefficients of the ocular and
corneal WAs were compared at each target direction.
Results: Only comatic aberrations were altered with changes in target direction.
Corneal vertical coma for the top and bottom targets was changed 0.088 and -0.094
µm from that of the center target respectively. Corneal horizontal coma of the leftside and right-side was changed 0.088 and -0.083µm from that of center respectively.
Ocular vertical coma for the top and bottom targets was changed 0.037 and -0.047µm
from that of center respectively. Ocular horizontal coma of left-side and right-side was
changed 0.026 and -0.026µm from that of center respectively. All of these differences
were statistically significant at the p< 0.001 level. The variations of ocular coma were
smaller than those of the cornea. We found a statistically significant proportional
compensation for horizontal corneal coma (i.e. the amount of compensation of corneal
coma by the internal optics of the eye was proportional to the magnitude of corneal
coma). However we failed to demonstrate similar proportional compensation for
vertical coma.
Conclusions: We found that the magnitudes of both corneal and total optical coma
change away from the visual axis. As in the central retina, we failed to demonstrate
proportional compensation for vertical coma in the near peripheral retina.
CR: Y. Hirohara, None; T. Tanabe, None; T. Fujikado, None; H.C. Howland, None; T.
Mihashi, None.
Support: None
3325 - A108
Wavefront Aberrations in the Peripheral Retina Are Different in the Eyes of
Myopic and Emmetropic Young Adults
3326 - A109
Changes in Peripheral Refractive Error Due to Accommodation and Higher
Order Aberrations
C.E. Beck, J. Gwiazda, J. He. New England College of Optometry, Boston, MA.
C.A. Clark, P.S. Soni, L.N. Thibos. School of Optometry, University of Indiana,
Bloomington, IN.
Purpose: To measure wavefront aberrations in the central and peripheral retina and
compare the amounts and patterns in myopic and emmetropic subjects.
Methods: The Complete Ophthalmic Analysis System (COAS) was used to measure
wavefront aberrations in the eyes of 36 young adult subjects (27 females, 9 males; mean
age = 23.6 yrs). 18 were emmetropic (mean Rx = -0.10 D +/- 0.31) and 18 were myopic
(mean Rx = -3.32 D +/- 1.86). Mean cylinder was -0.15D. The COAS was aligned to the
subject’s right eye which saw a red light surrounded by concentric circles. A mirror
was aligned to the left eye so that they saw a target 33 cm away with small black letters
on a white background. Aberrations were measured centrally, at 10 and 30 deg nasally
and 10, 20, and 30 deg temporally. Three measurements were taken at each position.
Means of the three measurements were compared by position and refractive group,
using repeated measures ANOVA and t-tests for total RMS, higher order (HO) RMS,
and 7 Zernike aberration terms (Z2-2 ,Z22 ,Z3-3 ,Z3-1 ,Z31 ,Z33 ,Z40 ).
Results: For total RMS aberrations, there was a significant interaction between position
and refractive status (p<0.001). Aberrations were greater in the far periphery than
centrally and more aberrations were found in the temporal than nasal retina. More
aberrations were found in emmetropes than myopes at temporal 20 (p=0.0005) and 30
deg (p=0.0001). Higher order aberrations differed significantly across the 6 positions
(p< 0.0001), with more peripheral aberrations, but there were no refractive group
differences (p = 0.31) and no interaction between position and refractive group (p =
0.72). Similar to total RMS, main axis astigmatism (Z22) was greater in the far periphery
than centrally, and more astigmatism was found temporally than nasally. Z22 was
significantly greater in emmetropes than myopes at temporal 20 deg (p< 0.0001)
and temporal 30 deg (p< 0.0001). Oblique astigmatism (Z2-2) was positive nasally
and negative temporally, and was significantly greater in emmetropes than myopes
at nasal 30 deg (p=0.005). Horizontal coma (Z31) was positive nasally and negative
temporally, but only for emmetropes (in myopes it was positive by a small amount at
all positions). For the other higher order terms there were no consistent differences
between positions or between emmetropes and myopes.
Conclusions: Emmetropes were found to have higher total RMS aberrations than
myopes in the peripheral retina, mainly due to more astigmatism. The astigmatism
results are consistent with Hoogerheide et. al.(1971). Peripheral aberrations are now
being measured after a period of near work to see if the pattern changes in either
refractive group.
CR: C.E. Beck, None; J. Gwiazda, None; J. He, None.
Support: EY014817, T35EY007149
Purpose: Peripheral refractive error has been hypothesized to be a stimulus for
myopia progression. In addition, myopia progression has been heavily associated
with near work. To date, there is some question whether accommodation has an
effect on peripheral refractive error as different studies have shown conflicting
results. The purpose of this study is to examine the effects of accommodation on
peripheral refractive error.
Methods: 20 subjects with refractive error in the range of +4.00 to -7.00 participated in
this investigation. The Hartmann-Shack technique was used to measure the central
and peripheral refractive error at ±30° in the nasal and temporal periphery along the
horizontal meridian. A Badal optometer was installed to allow for targets at infinity
and for a 3 diopter stimulus at near. Central and peripheral refractive error was
measured with targets at distance and near.
Results: Peripheral refractive error was highly variable between subjects. Spherical
aberration was correlated with accommodative changes in peripheral refractive
error and explains much of the variance. This correlation was consistent with
similar changes in peripheral refractive error and spherical aberration such as in
orthokeratology. No other higher order aberrations were correlated with changes
in peripheral refraction.
Conclusions: Changes in spherical aberration may have an association with
changes in peripheral refractive error. If this is correct, it could explain some of the
discrepancies between past studies. If peripheral refractive error is important for
myopia progression, changes in spherical aberrations may be an important factor in
determining progression.
CR: C.A. Clark, None; P.S. Soni, None; L.N. Thibos, None.
Support: None
3323-3326
3327 - A110
Mapping of Off-Axis Refractive Errors in Myopic Eyes Using an AutoRefractometer
3328 - A111
The Effect of Pupils Size on the Measurement of Peripheral Refraction Using
the SureSightTM Autorefractor
S. Hasebe, M. Saito, H. Ohtsuki. Ophthalmology, Okayama Univ Medical School,
Okayama, Japan.
R.E. Payor, G. Schmid. Clinical Research, CIBA Vision Corp, Duluth, GA.
Purpose: Hyperopic defocus in the peripheral retina is thought to be a source of
elongation of the eye and hence progression of myopia in children. The aim of this
study was to determine the validity and reliability of a clinical method to evaluate
off-axis (peripheral) refractive errors in myopic eyes.
Methods: Recruited in this study were 21 adult subjects who had no ophthalmologic
abnormality except for refractive errors (refractive range: -1.25 D to -12.00 D). Subjects
were asked to successively look at 9- or 21-point fixation targets located within +/-30
x 30 degrees, refractive errors were measured using an open-field autorefractor
FR5000 (Grand Seiko) while subjects were looking at each target. Cycloplegic eye
drops were applied before the measurement. In each subject, a quadratic response
surface was fitted to the data, and their off-axis refractive errors were represented
in a 2-dimensional map (figure). Test-retest repeatability of this map was evaluated
by repeating the measurement after an interval of time and comparing the two
results.
Results: Compared with the axial refractive error, refractive errors in the peripheral
retina were frequently more hyperopic in patients with moderate to high myopia.
The amount of the difference in refraction between the fovea and peripheral retina
30 degrees from the fovea reached 8 D at most and significantly correlated to the axial
refractive error (R 2> 0.54, P<0.02) except in the lower meridian. Overall repeatability
of the map (95% limits of agreement) was +/-1.19 D, whereas that for the axial
measurement was +/-0.69 D.
Conclusions: The mapping of peripheral refractive errors demonstrated the
relationship between peripheral refractive errors and ocular shape as previously
reported under experimental conditions. Further studies are required to estimate
systematic measurement errors involved in this method.
Purpose: Clinical interest in the measurement of peripheral refraction is based on
recent theories on the role of the peripheral retina in emmetropization and conversely
refractive error development. While central subjective refraction, autorefraction and
aberrometry are well understood adapting these methods to peripheral refraction
raises new questions.
Methods: In this case we tested the Welch Allen® SureSightTM portable autorefractor
and varied pupil size from habitual (mean of 3.7mm) to dilated (greater than 6.0mm)
to test the effect of pupil size on the central and peripheral measurements. Central and
in 10 degree steps peripheral refractions were measured in nasal, temporal, superior
and inferior meridians until the ‘cylinder’ value exceeded the 3.00DC limit for the
instrument. For total of 16 subjects the undilated central and peripheral autorefractions
were compared with the corresponding dilated pupil measurements.
Results: Using the held-held portable design of the SureSightTM autorefractor it was
easy to measure central and peripheral refractions in any (not just the primary)
meridian out to the measuring limit of the instrument. Marked asymmetry of the
peripheral refraction was seen between the nasal and temporal (more peripheral
change) meridians while superior and inferior were similar and closer to the temporal
refractions. Hyperopic shift of the peripheral relative to the central refraction ranged
for less than 0.50D to greater than 2.50D in these 3 meridians. The mean change in
sphere equivalent peripheral refraction with pupil dilation was less than 0.25D which
is within the SureSightTM measurement repeatability.
Conclusions: The SureSightTM autorefractor can be used like a clinical retinoscope
to measure within 10 degrees of the visual axis while the patient fixates a distant
target to control accommodation. Peripheral measurements can be made by moving
away from the direction of gaze up to 30 to 50 degrees nasally and 20 to 40 degrees
temporally, superiorally and inferiorally. The instrument measurement is robust over
a range of pupil sizes from less than 4.0mm to greater than 6.0mm.
CR: R.E. Payor, CIBA VISION, E; G. Schmid, CIBA VISION, E.
Support: None
CR: S. Hasebe, None; M. Saito, None; H. Ohtsuki, None.
Support: None
3329 - A112
On and Off-Axis Comparative Contrast Sensitivity Performance of Progressive
Addition Lenses
3330 - A113
Naso-Temporal Asymmetry in Contrast Sensitivity in the Peripheral Visual
Field of Emmetropic Eyes
R.J. Nason, G.A. Zikos, S. Ali, A. Selenow. Institute for Vision Research, Manhattan
Vision Associates, NYC, NY.
A.R. Whatham1,2, A. Ho1,2, P. Sankaridurg1,2, F. Conrad1,2, D. Falk1,2, P. Lazon1,2, A.
Martinez1,2, B. Holden1,2. 1Institute for Eye Research, Sydney, Australia; 2Vision Cooperative Research Centre, Sydney, Australia.
Purpose: To compare the contrast sensitivity function of a conventional PAL to new
digitally surfaced designs with wavefront optimization, for both on and off-axis
distance viewing.
Methods: Contrast sensitivity (CS) was tested at 4, 8, 12 and 20 cpd at a test distance of
3 meters utilizing the Cambridge Research Systems Ltd. ViSaGe with a SONY GDM-F20
CRTand the Metropsis time interval, two-alternative, forced choice QUEST protocol.
The subjects were tested gazing through a 6 mm aperture at the following three points
in the lenses: Central fitting point (C), 12.5 deg temporally to the distance fitting point
(I) and 6 deg below the fitting point (T). 28 eyes of presbyopic subjects (mean age 55 yo)
were tested. All eyes were myopic (-0.75D to -8.00D Mean=-3.54D) with astigmatism
(-1.25 to -2.50 mean=-1.69). Two lens designs were tested. A conventional (Panamic)
and a digitally surfaced design with wavefront optimization (Physio).
Results: CS improvements up to 20% (C), 27% (I), 72% (T) and 22% overall were
measured with the Physio vs. the Panamic.
Physio vs. Panamic
Mean Difference
Lens Position
Central
Central Total
Inferior
Inferior Total
Temporal
Temporal Total
Total
Spatial Frequency
4
8
12
20
4
8
12
20
4
8
12
20
Percent Difference
13%
20%
9%
9%
13%
11%
17%
27%
18%
18%
31%
72%
28%
9%
35%
22%
Purpose: We investigated contrast sensitivity at nasal and temporal retinal locations
in emmetropic children and adults, and best corrected contrast sensitivity at these
locations in the adults.
Methods: Eight children (6 to 17 years) and six adults (18 to 40 years) monocularly
viewed, at 30 degrees nasal and temporal eccentricity in a computer-based test, either
a circular sinusoidal ring target of 2 cycles per degree or a luminance equivalent grey
screen over two consecutive screen displays in a temporal 4 alternative forced choice
task. Threshold was measured with a staircase procedure. Refractive error (RE) was
measured at 30 degrees eccentricity, nasal and temporal retina, using the Shin-Nippon
autorefractor. Peripheral contrast sensitivity was also measured in adult subjects at
30 degrees with optical correction of peripheral REs.
Results: Under habitual viewing conditions contrast sensitivity (mean ± SE) was
significantly better (p < 0.01) in the nasal retina than the temporal retina in both
children (0.78 ± 0.09 vs 1.12 ± 0.07 log units) and adults (0.62 ± 0.05 vs 1.15 ± 0.07 log
units). Spherical equivalent RE and J45 were not significantly different between nasal
and temporal locations (p > 0.05) in children and adults. However J0 was significantly
(p < 0.05) more negative (more against the rule astigmatism) in the temporal than
nasal retina in both children and adults. Naso-temporal asymmetry in contrast
sensitivity remained after correction of peripheral RE in adults (0.70 ± 0.06 vs 1.17
± 0.10 log units).
Conclusions: The nasal retina is 2 to 4 times more sensitive to contrast than the
temporal retina in children and adults. This has implications for understanding
peripheral retinal circuitry, early functional loss in retinal diseases such as glaucoma,
and eccentric fixation in the case of a central scotoma.
CR: A.R. Whatham, None; A. Ho, None; P. Sankaridurg, None; F. Conrad, None; D.
Falk, None; P. Lazon, None; A. Martinez, None; B. Holden, None.
Support: None CT: www.actr.org.au, ACTRN12607000454471
Conclusions: In-Vivo contrast sensitivity with PALs may be improved with newer
designs.
CR: R.J. Nason, Essilor, C; G.A. Zikos, Essilor, F; S. Ali, Essilor, F; A. Selenow,
Essilor, F.
Support: Essilor
3327-3330
382. IOL: Optical and Visual Performance Organizing Section: VI
3331 - A114
Intraocular Lens Model Eye Based on the Average Presbyopic Human Eye
3332 - A115
A Multi-Center Evaluation of Wavefront Aberrations in a Pseudophakic
Population
M.A. Lagana, D. Compertore, L. Costanza, I.G. Cox. Bausch & Lomb, Rochester, NY.
Purpose: The purpose of this study is to present the design of a new 43D model
eye that is geometrically and optically similar to the Liou and Brennan eye model.
A comparison is made between the 43D eye model and the ISO 11979-2, Annex C
model eye.
Methods: The industry-standard Liou and Brennan eye model [1] was used as the
baseline for an average presbyopic eye. The new 43D model eye was designed to be
geometrically and optically similar to the Liou-Brennan eye model. Three tests were
done to verify the design of the new 43D model eye. First, the total power of the 43D
model eye and an ISO 11979-2 eye model were measured and compared to the LiouBrennan eye model. Second, the spherical aberration (SA) of the 43D model eye and
an ISO 11979-2 model eye were also measured. Finally, the expected add power of a
simple two zone PMMA bifocal lens was analytically calculated using both model
eyes and compared to the Liou-Brennan eye model.
Results: The 43D model eye agrees better with the Liou-Brennan model geometrically
and optically than the current ISO 11979-2 model eye.
Conclusions: The new 43 D wetcell is better suited to testing IOL optical performance
than the ISO 11979-2 prescribed model eye.
[1] Liou H. and Brennan N.A., Anatomically accurate, finite model eye for optical
modeling, J. Opt. Soc. Am. A, Vol. 14, No. 8, Aug 1997, 1684-1695.
CR: M.A. Lagana, Bausch & Lomb, C; D. Compertore, Bausch & Lomb, E; L. Costanza,
Bausch & Lomb, C; I.G. Cox, Bausch & Lomb, E.
Support: None
3333 - A116
The Advantage of F4H5 for Removing Silicone Oil from the Surface of Silicone
Intraocular Lenses Compared to F6H8
Y. Liang1, A.M. Joussen1, W. Hiebl2, N. Kociok1. 1Ophthalmology, Heinrich-Heine
University, Duesseldorf, Germany; 2Fluoron AG, Neu-Ulm, Germany.
Purpose: This study was performed to compare the efficacy of perfluorobutylpentane
(F4H5) and perfluorohexyloctane (F6H8) in dissolving silicone oil from the surface
of silicone intraocular lenses.
Methods: Silicone lenses were examined after application of 10 µl- droplets of silicone
oil of two different viscosities (1000 and 5000 cSt) followed by repeated rinsing with
25 µl F4H5 or F6H8. To allow distinction between silicone oil and the solvents and to
measure the washing effect the silicone oil was stained by the fluorescent lipophilic
carbocyanine DiI. Microscopic examination was carried out under video control.
Results: 25 µl of F4H5 reduced the fluorescence of silicon oil 1000 or 5000 to 15 % and
28%, respectively. 25 µl of F6H8 reduced the fluorescence of silicon oil 1000 or 5000 only
to 45 % and 71%, respectively. 175 µl or 225 µl of F4H5 were able to completely remove
the droplet of silicone oil 1000 or 5000, respectively, whereas after washing with 225
µl of F6H8 there remained 0.3% and 0.9% of the silicone 1000 or 5000 fluorescence,
respectively.
Conclusions: A smaller volume of F4H5 than F6H8 is able to completely remove
silicone oil 1000 or 5000 from silicon lenses. The higher solubility of F4H5 to both,
silicon oil 1000 and 5000 will facilitate removing silicone oil from the surface of silicone
intraocular lenses. Intraocular use of F4H5 is safe and first clinical data underlines the
effectiveness as a washout agent after contact of silicone lenses with silicone oil.
CR: Y. Liang, None; A.M. Joussen, None; W. Hiebl, Fluoron AG, Neu-Ulm, I; N.
Kociok, None.
Support: None
R. Sun, K.H. Edwards. Clinical Affairs, Bausch & Lomb Inc, Rochester, NY.
Purpose: The objective of this study was to measure and evaluate the Higher
Order Aberration (HOA) and Spherical Aberration in a population of post-cataract
pseudophakic subjects.
Methods: Subjects who had previously undergone cataract surgery and primary
implantation of an IOL at least 6 months prior to participation in this study were
examined at a single visit during which each enrolled eye had the ocular wavefront
measurements taken. Wavefront aberration contributed by the optical system was
measured using the Bausch & Lomb Zywave (I/II) WaveFront Aberrometer. Wavefront
aberration contributed by the cornea was measured using the Bausch & Lomb Orbscan
Anterior Segment Analyzer (II/IIz). Wavefront aberration contributed by the IOL for
combined IOL models was calculated by subtracting the corneal contribution from
the wavefront aberration by the optical system.
Results: Spherical Aberration contributed by the IOL at 5 mm pupil was 0.17 compared
to 0.20 by the optical system. Eighty-six percents of total Spherical Aberration were
contributed by the IOLs. The cornea only contributed 14.0% of total Spherical
Aberration. When comparing Vertical Coma and Horizontal Coma contributed by
the IOL at 5mm pupil, once again, the major portion of the Comas was from the IOL.
In addition, a significant correlation was found between HOA and visual acuity at
5mm pupil and at low contrast condition (p=0.03).
Conclusions: The results of this study showed that a major portion of the Coma and
Spherical Aberration in the optical system were contributed by IOLs. There was a
correlation between HOA and visual acuity at 5mm pupil in low contrast condition,
indicating that visual acuity worsened when HOA increased. Future studies should
continue to investigative the wavefront aberration contributed by spherical and
aspheric IOLs in pseudophakic eyes and the association between wavefront aberration
and visual performance.
CR: R. Sun, Bausch &Lomb, E; K.H. Edwards, Bausch &Lomb, E.
Support: None
3334 - A117
Calcification of Ocular Biomaterials
R. Jain. Biomedical Research, Advanced Medical Optics, Inc., Santa Ana, CA.
Purpose: The present study is a continuation of the subcutaneous implantation study
evaluating intraocular lens (IOL) calcification, which the author presented at ARVO
2006. The goal of the continued analysis was to determine whether the calcium and
phosphorus deposits were only on the surface of the IOLs or if they were embedded
in the IOLs.
Methods: Commercial IOLs were implanted subcutaneously in New Zealand
White rabbits for 70 ± 2 days per Buchen et. al., 2001. Hydrophilic IOLs included the
Akreos Adapt and Fit, Acri.Smart, ThinOptX, Rayner 570C, and Hydro view IOLs.
Hydrophobic IOLs included the acrylic AR40e IOL; and the silicone Clariflex IOL.
After explantation, scanning electron microscopy (SEM), and energy dispersive
spectroscopy (EDX) analysis, the samples were subjected to atomic force microscopy
(AFM) to determine the surface profile and topography.
Results: AFM analysis of selected hydrophilic IOLs demonstrated a change in
surface topography of up to 2.55 µm in depth with “multi-nucleated” calcium and
phosphorus structures ranging in diameter from 5 to 60 µm. Analysis revealed no
signs of calcification in the hydrophobic acrylic or silicone IOLs.
Conclusions: In the study presented at ARVO 2006, 5 of 6 hydrophilic IOLs showed
obvious signs of calcification as demonstrated by SEM and EDX analysis. The current
analysis demonstrates that the presence of calcium and phosphorus in the hydrophilic
IOLs is not only a surface phenomenon. AFM demonstrates that the calcium and
phosphorus structures are embedded in the IOLs.
CR: R. Jain, Advanced Medical Optics, Inc. (Santa Ana, CA), E.
Support: None
3331-3334
3335 - A118
Refractive State of the Enucleated Equine Eye After Placement of a 30D
Intraocular Lens
3336 - A119
The Negative Dysphotopsia of IOLs
H. Zhao1, J.T. Holladay2, C.R. Reisin1. 1Advanced Medical Optics, Inc, Santa Ana, CA;
2
Holladay Consulting, Inc, Bellaire, TX.
R.J. McMullen, Jr., J.H. Salmon, M.G. Davidson, B.C. Gilger. Ophthalmology, North
Carolina State Univ, Raleigh, NC.
Purpose: In a previous study we determined that a 30D intraocular lens implant
should be appropriate to achieve emmetropia in adult horses. Pre-operative anterior
chamber depth (ACD) plus 50% of the crystalline lens thickness (CLT) was used as
the post-operative anterior chamber depth (PACD) in our calculations. Therefore, the
purpose of this study was to evaluate the effect of a 30D intraocular lens implant on
refraction in enucleated equine globes and to determine the post-operative ACD.
Methods: Extracapsular lens extraction and placement of a 30D equine IOL was
performed on 6 enucleated equine eyes. Intraocular pressure was maintained at 22-25
mmHg with injections of saline through the optic nerve. Streak retinoscopy and A/BMode ultrasound was performed on each eye prior to, and immediately following,
lens extraction and IOL implantation. A/B-Mode ultrasound was performed to obtain
the following pre- and post-operative globe dimensions: ACD, CLT, and axial globe
length (AxL). Streak retinoscopy was performed on 31 normal horses to provide
information on the normal equine refractive state.
Results: Pre-operative mean refractive error of -0.46D (SD +/- 1.03) was obtained
from 6 eyes. Pre-operative globe dimensions: ACD: 7.12 mm (SD +/- 0.82), CLT: 11.32
mm (SD +/- 0.81), and AxL: 40.51 mm (SD +/- 1.26). Post-operative anterior chamber
depth (PACD): 10.76 mm (SD +/- 1.16). None of the IOLs were positioned posterior
to the pre-operative ACD + 50% CLT. The pre- to post-operative ACD ratio averaged
0.68 (SD +/- 0.59). The overall mean refractive error of adult horses in our clinic was
0.29D (SD +/- 0.77). Implantation of a 30D IOL led to an average overcorrection of
2.96D (SD +/- 0.84).
Conclusions: Normal horses are approximately emmetropic. Due to a more anterior
PACD than that estimated in our previous work, a 30D IOL may overcorrect normal
horses based on this in vitro study. An IOL with the refractive power of approximately
24 - 25.5D may be appropriate for the horse.
CR: R.J. McMullen, Acri.Vet Inc., F; J.H. Salmon, Acri.Vet Inc., F; M.G. Davidson,
Acri.Vet Inc., F; B.C. Gilger, Acri.Vet Inc., F.
Support: Vision for Animals Foundation Grant 2006-2007
3337 - A120
Cell Adhesion on Intraocular Lenses of Various Materials in Japanese Patients
N. Ishikawa, T. Miyamoto, S. Saika. Department of Ophthalmology, Wakayama
Medical University, Wakayama, Japan.
Purpose. To study the difference of cell adhesion by foreign-body reaction on
intraocular lenses (IOLs) of various materials that were extracted from Japanese
patients.
Methods. Extracted IOLs of PMMA (n = 271), soft acrylic material (n = 117), and slicone
(n = 48) were studied. Samples were collected by the Japanese Society of Cataract and
Refrcative Surgery. Each IOL was stained with hematoxylin and eosin and observed
under light microscopy. The number of cells on the anterior surface of the optic was
counted. The samples were grouped as IOLs extracted after 1 to 6, 6 to 12, 12 to 24 or
over 24 months after implantation.
Results. Cell adhesion on PMMA IOLs were significantly higher as compared with
on silicone IOLs edxtracted 6 to 12 months post-implantation. There was no statistical
difference of cell numbers on PMMA IOLs and on acrylic IOLs.
Conclusion. Cell adhesion by foreign-body reaction was less on silicone IOLs as
compared with PMMA IOL.
CR: N. Ishikawa, None; T. Miyamoto, None; S. Saika, None.
Support: None
Purpose: To identify and assess angular scotoma of the intraocular lens (IOL), including
its appearance and relative intensity. This phenomenon potentially produces noticeable
negative dysphotopsia in pseudophakic eyes.
Methods: The interactions of light rays from a wall in a typical clinic room (Lambersian
Dispersion) and an eye model with a double-square-edge IOL were examined using
the ZEMAX ray-tracing program (ZEMAX Development Corp.). The potential of the
angular scotoma to produce negative visual sensations was analyzed from plots of
the spatial location and the energy distribution of rays forming the retinal image
from previous studies of positive dysphotopsias.
Results: Angular scotoma is produced by the typical double square-edge IOLs. It is
caused by the internal reflection from the IOL edge. The missing light appears as a
dark line or arc on the periphery of the retina at about 68 -70 degrees from the center
with a width of about 5 degrees depending on the specific design of the IOL design
and particularly the design of the edge. Because the human visual field only exceeds
65 degrees in the temporal field, the patient only perceives the negative dysphotopsia
temporally. The average intensity of the dark line was about 3-4 orders of magnitude
weaker than the average intensity of the surrounding area filled with refracted light
by the lens edge and the optical surface. We also found that the width and position
of the dark line is dependent on the depth of the IOL in the eye relative to the pupil,
corneal power, and pupil size.
Conclusions: We have simulated the pseudophakic angular scotoma produced by
IOLs with double square edges. This scotoma potentially produces the negative
dysphotopsia phenomenon. The scotoma is caused by the internal reflection from the
square edge of the IOL. Our simulations have confirmed the existence of the persistent
narrow dark arc or line shape on the peripheral retina on temporal orientations,
which is much weaker in intensity than the primary images or the glare images on
the surrounding area.
CR: H. Zhao, Advanced Medical Optics, E; J.T. Holladay, Advanced Medical Optics,
C; C.R. Reisin, Advanced Medical Optics, E.
Support: None
3338 - A121
Affects of Position and Shape of CCC (Continuous Curvilinear Capsulorhexis)
on Dislocation of Intraocular Lens (IOL) Following Cataract Surgery
M. Nagata, H. Matsushima, K. Mukai, W. Terauchi, T. Senoo. Ophthalmology, Dokkyo
Medical University, Mibu, Japan.
Purpose: Dislocation of intraocular lens (IOL) will cause decrease of visual function
for recent advanced IOLs such as aspheric and multi focal. The affects of the position
and shape of CCC (continuous curvilinear capsulorhexis) on dislocation of intraocular
lens (IOL) following cataract surgery were evaluated.
Methods: The study was conduct 102 eyes of 92 patients that had undergone cataract
surgery in our hospital. SA60AT (Alcon), VA-60BB (HOYA) were randomly selected
and implanted after phacoemulsification. The series comprised 44 eyes in which the
edges of IOL optics were covered by the anterior capsule (complete cover, CC group)
and 58 eyes in which the edges of IOL optics was incompletely covered (non complete
cover, NCC group). The tilting and decentration of IOLs were analyzed by EAS1000
(NIDEK) at 1 weeks, 1 month , 3 months and 6 months.
Results: The average of tilting in SA60AT were 3.83±2.48 ° (CC group) and 4.93±2.35
° (NCC group) , the average of tilting in VA-60BB were 2.07±0.93 ° (CC group) and
4.68±1.90 ° (NCC group) after 6 months postoperatively. The average of decentraion
in SA60AT were 0.31±0.21mm (CC group) and 0.39±0.19mm (NCC group) , the average
of decentraion in VA60BB were 0.15±0.07mm (CC group) and 0.31±0.25mm (NCC
group) after 6 months postoperatively. The tilting and decentraion in NCC group
were significantly higher than CC group in the both of IOLs.
Conclusions: Unsuitable position and shape of CCC increase the dislocation of IOL.
Precise and certain CCC technique might be important to obtain visual function for
advance IOLs.
CR: M. Nagata, None; H. Matsushima, None; K. Mukai, None; W. Terauchi, None; T.
Senoo, None.
Support: None
3335-3338
3339 - A122
ICL Intraocular Lens Implantation for the Correction of Myopia in Patients
With Previous Retinal Detachment, 2 Years Follow Up
3340 - A123
In vitro Measurent of the Optical Quality of an Intraocular Lens Considering
Translations, Rotations and Titls
F. Peniche, A. Haber, A. Lopez. Cornea & External Diseases, Institute of
Ophthalmology, Mexico City, Mexico.
N. Lopez-Gil1, S. Bonaque1, R. Montés-Micó2, V. Fernández-Sánchez1, R. Gómez3, J.
Castejón-Mochón4. 1Ciencias de la Visión, Universidad de Murcia, Murcia, Spain;
2
Optics, Universidad de Valencia, Valencia, Spain; 3Clínica Oftalmológica Las
Claras, Salamanca, Spain; 4Universidad SEK, Segovia, Spain.
Purpose: To determine the efficacy and Safety of ICL IOL Implantation for the
correction of high myopia in patients with previous retinal detachment.
Methods: ICL Intraocular lens implantation was performed in 7 eyes with high myopia,
mean spherical refraction was -15.00 (R 12-18); 8 months before, patients presented
regmatogenous retinal detachment-no macula involment, mean RRD time was 8
months (R6-10), they underwent reatachment retinal surgery (Vitrectomy/escleral
buckle); UCVA, BCVA, refraction, cornealtopography,anterior and posterior segment
revision was performed.
Results: mean UCVA preoperative was 6/200 (R 4/200-8/200), mean BCVA preoperative
was 20/30 (R 20/20-20/40), mean spherical preoperative refraction was -15.00 (R 12-18),
mean follow up time was 23 months (R 21-25), mean UCVA postoperative was 20/30
(R 20/20-20/40), mean BCVA postoperative was 20/25 (R 20/20-20/30), mean spherical
postoperative refraction was -0.75 (R -0.25/-1.25), retina is atachment and no sign or
sintoms are present at this time.
Conclusions: Our datta suggest that ICL intraocular lens implantation is efficacy for
reduction of myopia and is safe in patients with previous retinal reatachment surgery,
longer follw up is needed to determinate the effect of the ICL on the retina.
CR: F. Peniche, None; A. Haber, None; A. Lopez, None.
Support: None
Purpose: Intraocular lenses (IOLs) are theoretically designed to produce retinal images
with a high quality for object placed at one or more distances. However, oftenly, visual
performances after surgery (specially IOLs with aspheric designs) are limited by
descentrations and/or tilts. We have studied, in vitro, the optical quality of several
IOLs with a new device.
Methods: A comercial aberrometer (Imagine Eyes irx3) together with a new device which
consist on an artificial eye was used to obtain the in vitro wavefront in monofocal and
multifocal IOLs after subtrating the aberrations of the artificial eye. The artificial eye has
the possibiliy to produce a descentration, rotation and/or a tilt in relation to the artificial
cornea. From the wavefront outcomes we obtained several optical quality metrics such us
the PSF or the MTF. The aberrometer used also allows obtaining wavefront measurement
for different object possitons and different pupil sizes simulating near vision performance
for multifocal IOLs. Repeatability and exactitude of the system was tested comparing its
results with computer simulations on a model eye.
Results: Repited measurements on an IOL for a 5 mm pupil show a standard deviation
in all Zernikes coefficients (up to 8th-order) always less that 0.01 microns except in
the case of defocus for which standard deviation was 0.06 microns (about 0.07 D). In
vitro measurement of the IOL differs in less than 0.01 D respect the optical simulations
generated by the model eye. The figure represents a typical in vitro wavefront of a
multifocal IOLs with a vertical decentration of 0.3 mm. Astigmatism and higher-order
aberrations, specially coma, was generated after tilting and decentering the IOL.
Conclusions: A new device was tested and used to measure in vitro optical performance
of IOLs. The system may be used to predict tolerances of diferent IOLs under possible
rotations and translations before the surgery.
CR: N. Lopez-Gil, None; S. Bonaque, None; R. Montés-Micó, None; V. FernándezSánchez, None; R. Gómez, Clínica Oftalmológica Las Claras, F; J. Castejón-Mochón,
None.
Support: Junta de Castilla y León, Grant SEK01B07
3341 - A124
The Effects of Corneal Aberrations, Tilt and Decentration on Intraocular Lens
Performance
3342 - A125
Cognitive and Visual Function in Phakic and Pseudophakic Eyes: An
Intraocular Lens Filter Study
A.C. Kingston1A, G.E. Altmann1B, P. Ludington1A. AOptical Design and Metrology,
B
Global Surgical, 1Bausch and Lomb, Rochester, NY.
G.A. Gibson, L.N. Davies, J.S. Wolffsohn. School of Life & Health Sciences, Aston
University, Birmingham, United Kingdom.
Purpose: The aim of this study is to determine how corneal aberrations, and intraocular
lens (IOL) tilt and decentration affect retinal image quality. The Tecnis Z9000, B&L
LI61U and B&L SofPort AO IOL’s were investigated.
Methods: A Monte-Carlo simulation with (1000) trials was done to assess IOL
performance in the presence of corneal aberrations, and tilt and decentration of the
IOL itself. Each lens was evaluated at a 3.0mm and 5.0mm pupil with photopic and
scotopic lighting conditions, respectively. For each Monte-Carlo trial, a 20/20 convolved
E was created and the area under the Modulation Transfer Function (MTF) curve was
calculated. The convolved E was used to generate a pattern recognition score. The
average pattern recognition score and area under the MTF curve were both used to
predict the retinal image quality.
Results: When the lenses were evaluated at a 3.0 mm pupil diameter, the amount of
spherical aberration inherent in each IOL was small. As a result, the corneal aberrations,
along with tilt and decentration of the lens itself, became the dominating factors of
optical performance. Even with a reduction in spherical aberration, the SofPort AO
yielded a better average pattern recognition score and area under the MTF curve
than the Tecnis Z9000 or LI61U lenses. Also, on average the SofPort AO had less
variability across the Monte-Carlo eye models, whereas the Tecnis Z9000 had the
largest variability at both pupil sizes. For a pupil diameter of 5.0 mm, the average
area under the MTF curve for the SofPort and Tecnis IOL’s was approximately equal.
However, the differences in pattern recognition scores between all three lens types
became more evident. The pattern recogition scores showed that the SofPort AO
performed better optically than the two lenses which have inherently larger spherical
aberration.
Conclusions: As the pupil size increased the amount of coma and astigmatism
produced by the decentered and tilted Tecnis IOL increased. This is due to the fact
that the Tecnis IOL is a higher-order asphere. The presence of these two aberrations
yielded lower average pattern recognition scores due to the asymmetric blurring
of the convolved E’s and also a higher variability in scores across the (1000) trials.
Since the SofPort AO lens is an aberration-free IOL it was less affected by the corneal
aberrations, and the tilt and decentration of the lens itself.
CR: A.C. Kingston, Bausch & Lomb, E; G.E. Altmann, Bausch & Lomb, E; P.
Ludington, Bausch & Lomb, E.
Support: None
Purpose: To examine the effect of short-wavelength intraocular lens (IOL) filters on
cognitive and visual function in phakic and pseudophakic eyes.
Methods: Twenty-four phakic eyes of 24 subjects (mean age 26.8±6.0 years) and
22 eyes of 22 subjects fitted with a standard IOL (mean age 74.1±9.1 years) were
assessed. Measurements of visual acuity (logMAR), contrast sensitivity (Pelli-Robson
and CSV 1000-E), colour discrimination (Farnsworth-Munsell 100-Hue), reading
speed (MNRead) and scotopic sensitivity (SST-1) were performed. In addition, the
phakic cohort also performed a cognitive function test (two-alternative forced-choice
paradigm) and short-wavelength automated perimetry (SWAP). Each phakic subject
wore three tinted spectacle lenses in a randomised sequence; an additional shortwavelength filter was introduced for the pseudophakic group. Three of the four filters
were matched to the transmission characteristics of the Alcon AcrySof Natural, Bausch
& Lomb VioletShield and the AMO OptiBlue (pseudophakic only) violet-blocking IOLs.
The control condition was a UV blocking filter.
Results: In the phakic cohort, mean defect scores for SWAP were found to be
significantly higher with the AcrySof Natural tinted lens (-2.14 ± 1.85 dB) compared to
the VioletShield (-1.34 ± 1.92 dB) and the control lens (-1.09 ± 1.65 db; p<0.01). Further,
cognitive function was attenuated with the AcrySof Natural lens compared to the
VioletShield, and the control lens (p<0.05). All other outcome measures were comparable
between conditions. The different transmission characteristics of the filters, however,
had no influence on the visual performance of the pseudophakic group.
Conclusion: Subjects’ performance with the AcrySof Natural, VioletShield and OptiBlue
filters were comparable to the UV blocking control for all measures, with the exception
of SWAP and cognitive function in the phakic group. Here, the AcrySof Natural filter
appeared to reduce the subjects’ short-wavelength sensitivity, and cognitive ability.
CR: G.A. Gibson, Bausch & Lomb, F; L.N. Davies, Bausch & Lomb, F; J.S. Wolffsohn,
Bausch & Lomb, F; Bausch & Lomb, C.
Support: EPSRC Grant CASE/CNA/05/51
3339-3342
3343 - A126
Blue-Light Filtering IOLs May Offer Better Visual Acuity Under Low Contrast
Levels
3344 - A127
Evaluation of Protective Effects Using Different Foldable Acrylic Yellow Tinted
Intraocular Lenses
J. Li1,2, D. Garman1. 1Ophthalmology Clinic, VA Medical Center, Salem, VA;
2
Department of Ophthalmology, University of Virginia, Charlottesville, VA.
H. Matsushima, K. Mukai, T. Senoo. Ophthalmology, Dokkyo Medical University,
Shimotsuga-Gun, Japan.
Purpose: To compare the visual acuity (VA) under different contrast levels (100%,
25%, 10% and 5%) in patients receiving a UV and blue-light filtering IOL (Alcon
AcrySof Natural SN60AT) in one eye and a UV-only filtering IOL (Alcon AcrySof
SA60AT) in the other.
Methods: Patients who had implantation of a SN60AT IOL in one eye (SN group) and
a SA60AT IOL in the other eye (SA group) were identified. Inclusion criteria included
age between 50 and 80 years, best corrected visual acuity (BCVA) of 20/25 or better,
agreeing to participate in the study, which was approved by the Medical Center IRB,
and signing the informed consent. Exclusion criteria were diabetes, posterior capsular
opacity, glaucoma, macular degeneration and astigmatism greater than 1.5 D. A total
of thirteen patients completed the study. Visual acuity in four different constrast levels
was obtained with a multi-functional visual acuity tester (MFVA100) under mesopic
condition, and the pupil size was measured with a Colvard infrared pupillometer
(Oasis) in the same luminance condition.
Results: The mean BCVA was -0.016 ± 0.037 logMAR in SN group and -0.015 ± 0.086
logMAR in SA group under 100% contrast level. The mean difference of BCVA in SN
group from that in SA group under 25%, 10% and 5% constrast levels were -0.136 ±
0.165, -0.221 ± 0.312 and -0.223 ± 0.263 logMAR, respectively. The mean pupil diameter
in millimeters was 4.4 ± 1.1 (SN group) and 4.4 ± 1.2 (SA group).
Conclusions: The two groups had similar BCVA under 100% contrast level. However,
the SN60AT IOLs produced better BCVA than the SA60AT IOLs under lower contrast
levels (25%, 10%, and 5%). The yellow filter IOLs may provid patients with better visual
function for conducting daily life activites, such as working and driving under low
contrast conditions.
CR: J. Li, None; D. Garman, None.
Support: Salem Research Institute
Purpose: To evaluate the protective effects of yellow tinted intraocular lenses (IOLs),
investigate changes in visible light-induced photo-oxidization and the inhibitory
effects of various acrylic tinted intraocular lenses (IOL) on photo-oxidation were
analyzed experimentally.
Methods: Three types of non-tinted (VA-60BB, HOYA; SA60AT, Alcon; AU-6, Menicon)
and tinted IOL (YA-60BB, HOYA; SN60AT, Alcon; AN-6, Menicon) were prepared. To
investigate oxidation from visible light, cultured human retinal pigment epithelial
cells were prepared, and cultured until confluent in a 96-well dish. The pigment
epithelial cells were irradiated with artificial sunlight (Yamashita Denso) either
directly or through various IOLs, for 30, 60, and 90 minutes. After light exposure lactate
dehydrogenase (LDH) levels of the culture medium supernatant were measured to
assess the amount of cell damage. Measurements of the amount of LDH precipitated
as a result of cell damage was based on the detection of diformazan, the final product
in the reaction system, at 560 nm. Statistical analysis was performed using a multiple
comparison test (Fisher’s PLSD), with a significance level of p<0.05.
Results: LDH levels in retinal pigment epithelial cells increased to 1.2 mU/50 μl as a
result of exposure to visible light. However, LDH level of non-tinted IOLs were 0.44
mU/50 μl (VA-60BB), 0.55 mU/50 μl (SA60AT), 0.63 mU/50 μl (AU-6) respectively. LDH
level of tinted IOLs were 0.37 mU/50 μl (YA-60BB), 0.29 mU/50 μl (SN60AT), 0.30 mU/50
μl (AN-6) respectively. There are a statistically significant difference amoung control
group, non-tinted IOL group and tinted IOL group.
Conclusions: Visible light causes photo-oxidation, which damages intraocular tissue.
Results suggest that tinted IOLs are effective in inhibiting tissue damage from visible
light.
CR: H. Matsushima, None; K. Mukai, None; T. Senoo, None.
Support: None
3345 - A128
Spectral Transmission of Clear and Yellow pHEMA IOL Pre-Post 6 Months
Implantation in Rabbits
3346 - A129
Measuring Scattered Light in Patients Implanted With Iols Using a HighSensitivity Double-Pass Instrument
N.M. Pumariega1,2, E. Arrieta-Quintero1, A. Amelinckx1, I. Nose1, W. Lee1, D. Borja1,2, F.
Manns1,2, M. Aguilar1,2, J.-M. Parel1,3. 1Ophthalmic Biophysics Center, Bascom Palmer
Eye Institute, Univ. of Miami Miller School of Medicine, Miami, FL; 2Biomedical
Optics Laboratory, Dept. of Biomedical Engineering, Univ. of Miami College of
Engineering, Coral Gables, FL; 3University of Liege, Ophthalmology, CHU SartTillman, Liege, Belgium.
G. Perez1, M. van der Mooren2, P. Piers2, P. Artal1. 1Laboratorio de Optica, Universidad
de Murcia, Murcia, Spain; 2AMO, Groningen, The Netherlands.
Purpose: To compare the spectral stability and biocompatibility of yellow and clear
IOLs.
Methods: A 300-600 nm portable testing system was designed using a fiber optic
spectrometer (#SM240, Spectral Products-CVI, Putnam, CT) and a deep blue-white
LED source with diffuser, iris diaphragm, voltage regulator and a transparent table
supporting a sterile BSS filled Petri dish to hold the sample. Sterile IOLs of both types
underwent spectral analyses. The study adhered to the ARVO Statement for the use of
animals in research and followed ISO/DIS 11979-5 and approved institutional animal
care guidelines. 12 NZW rabbits were implanted with IOLs having the same physical
dimensions; 6 received a clear and 6 a yellow pHEMA IOL (Quatrix, 20D, Croma-Pharma,
Austria) and underwent weekly ophthalmic exams for 6 months. Following euthanasia,
a ring conforming to the anterior sclera was bonded with cyanoacrylate to the enucleated
globe which was sectioned leaving an intact rim containing the lens or IOL in the capsular
bag, zonules, ciliary body, anterior vitreous, hyaloid membrane, and sclera. The tissue
sections underwent Miyake and shadowphotography exams and spectral transmission
measurements. The IOLs were explanted and additional spectral measurements carried
out. All tissues underwent histology.
Results: Surgery and follow-up were uneventful. As with Acrysof and other IOLs
(Fujiwara et al, ARVO IOVS 2001;42(4):S285 & 2001;42(4):S285) all eyes had PCO at 1 month.
Both IOLs were equally biocompatible. No clinical and histology differences could be
found between the 2 groups. Miyake and shadowphotography at 6 months showed de
novo lens fibers in all eyes reducing transmission and impacting the spectra compared to
the crystalline lens of unoperated contralateral eyes. There were no significant differences
between the spectra of explanted and control IOLs.
Conclusion: The spectral characteristics of clear and yellow hydrophilic pHEMA IOLs
remain stable following long term implantation in rabbits. The addition of a yellow
chromophore to pHEMA did not alter biocompatibility.
Support: Florida Lions Eye Bank; Croma-Pharma GmbH; NIH Center Grant P30-EY014801;
Research to Prevent Blindness; Henri and Flore Lesieur Foundation (JMP)
CR: N.M. Pumariega, None; E. Arrieta-Quintero, None; A. Amelinckx, None; I. Nose,
None; W. Lee, None; D. Borja, None; F. Manns, None; M. Aguilar, None; J. Parel, F, F.
Support: Florida Lions Eye Bank; Croma-Pharma GmbH; NIH Center Grant P30-EY014801;
Research to Prevent Blindness; Henri and Flore Lesieur Foundation (JMP)
Purpose: To quantify and compare light scatter in patients implanted with different
types of IOLs using a new high-sensitivity instrument that employs a wide-angle
double-pass technique.
Methods: Recording double-pass retinal images of a point source is a successful and
widely used objective method for evaluating the optical quality of the eye (Santamaria,
Artal & Bescos, JOSAA,1987). We have built a new system that uses this concept and
is optimized to detect the low light levels in the outer part of retinal images. An
important characteristic of the instrument is its wide angle detection compared to
the 30 minutes of visual field that is typical of standard double-pass instruments. An
adapted version of the instrument was built for recording images of pseudophakic
eyes in a clinical environment using infrared light for illumination.
Results: We recorded wide-angle double-pass images in both pseudophackic eyes and
an artificial eye with a dynamic range of 5 log units. By computing a scatter parameter
as the quotient of the light reaching different retinal locations, we quantified the
changes in the light scattered between different types of multifocal and monofocal
IOLs. At the inner part of the retinal image, below 1 degree, the scatter parameter of
diffractive multifocal IOL is around 70% higher than that for a monofocal IOL, whereas
at outer parts, the difference is around 30%. Smaller, but still measurable,differences
were found among different types of multifocal IOLs.
Conclusions: A new instrument that objectively measures the scattered light induced
by multifocal IOLs has been designed and built. We used the system to quantify light
scattering of pseudophakic eyes with different IOLs. These objective data could be
used in the design stage of the multifocal IOL to reduce induced scatter, which would
improve quality of vision.
CR: G. Perez, AMO, F; M. van der Mooren, AMO, E; P. Piers, AMO, E; P. Artal,
AMO, F.
Support: Advanced Medical Optics, Groningen, The Netherlands & MEC_FIS2004-2153
(Spain).
3343-3346
Wednesday, April 30, 8:30 AM - 10:15 AM Hall B/C Poster Session Program Number/Board # Range: 3773-3801 / A50-A78
412. Lens: Optical and Mechanical Properties Organizing Section: VI Contributing Section: LE
3773 - A50
Relative Contribution of Gradient Index Distribution and Surface Geometry to
Spherical Aberration in Isolated Primate Crystalline Lenses
3774 - A51
Paraxial Optical Model of the Crystalline Lens With Continuous Refractive
Index Gradient
A. de Castro1, D. Borja2,3, S. Uhlhorn2, F. Manns2,3, S. Barbero1, J. Parel2,4, S. Marcos1.
1
Instituto de Optica, Consejo Sup de Investigaciones Cientificas, Madrid, Spain;
2
Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami,
Miami, FL; 3Department of Biomedical Engineering, University of Miami College
of Engineering,, Coral Gables, FL; 4Vision Cooperative Research Centre, Sydney,
Australia.
F. Manns1,2, A. Ho3,4, D. Borja1,2, J.-M. Parel1,3. 1Ophthalmic Biophysics Center, Bascom
Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL;
2
Biomedical Optics Laboratory, Department of Biomedical Engineering, University
of Miami College of Engineering, Coral Gables, FL; 3Vision Cooperative Research
Centre, Sydney, Australia; 4Institute for Eye Research, Sydney, Australia.
Purpose: The optical properties of the crystalline lens (and the spherical aberration in
particular) are affected by the geometry of the surfaces and the gradient index (GRIN)
distribution. We used experimental data of laser ray tracing spot diagrams and surface
shape geometry on isolated primate crystalline lenses to estimate the GRIN profile and
its relative contribution to spherical aberration.
Methods: A laser ray tracing system (with a diode laser, x-y scanner, and CCD camera)
was used on isolated lenses. The lenses were submerged in preservation media in a BK7
container and the camera was positioned under the container. The lenses were scanned
at 0, 90 and 45 deg meridians, and a total of 100 spots were obtained per lens, on 4-mm
diameters. The container’s window thickness and the distances crystalline lens/container/
CCD camera were measured in situ with optical coherence tomography (OCT). The shapes
of the crystalline lens were measured by shadowphotography or OCT. The optimization
method to retrieve the GRIN from the CCD spots used genetic algorithms combined
with dumped least squares. We used a GRIN bielliptical model (n=c0+c1·r2). Similarly,
but using a constant index, we calculated the effective homogeneous index of each lens.
We report data on two crystalline lenses: an 8-year old cynomologus monkey (M) lens
and a 48-year old human (H) lens.
Results: 1) The retrieved surface index was 1.367 (M) and 1.372 (H) and the nucleus
index was 1.437 (M) and 1.414 (H). 2) The effective index was 1.448 (M) and 1.438 (H),
respectively. 3) The relative contribution of surface power and GRIN to the lens power
was 7.43 /39.04 D (M) and 4.20 /15.43 D (H), respectively. 4) The relative contribution of
lens surfaces and GRIN to spherical aberration was 0.080/-0.204 μm (M) and -0.007/-0.141
μm (H), respectively. 5) Assuming an effective index, the spherical aberration was 0.553
μm (M) and -0.018 μm (H).
Conclusions: 1) GRIN plays a significant role on the optical properties of the lens, and
spherical aberration in particular. While the reconstructed GRIN profile is consistent
with the experimental data, other models could be used in the method, with additional
input parameters.
CR: A. de Castro, None; D. Borja, None; S. Uhlhorn, None; F. Manns, None; S. Barbero,
None; J. Parel, None; S. Marcos, None.
Support: I3P-CSIC Predoc/Postdoc; NIH 2R01EY14225, 5F31EY1539, P30EY14801,
F32EY15630; Florida Lions Eye Bank; Research to Prevent Blind.; Lesieur Foundation;
CRC, Australia; FIS2005-04382, Spain; EURYI Award
3775 - A52
The Change of the Equivalent Refractive Index of the Crystalline Lens as a
Function of Accommodation Response Measured With Scheimpflug Imaging
and Aberrometry
Purpose: To determine the effect of the refractive index profile and its changes with
age on the crystalline lens power.
Methods: The paraxial differential equation for the ray path in a crystalline lens
with continuous refractive index gradient was solved to derive an expression of the
contribution of the gradient to the lens power. The crystalline lens was modeled
using published values of the curvature, thickness (Rosen et al, Vis Res 2006) and
refractive index profile (Jones et al, Vis Res, 2005) obtained on isolated lenses. The
paraxial gradient is characterized by the axial variation of the refractive index, n(z),
and curvatures of the isoindicial surfaces, K(z). The functions n(z) and K(z) were
modeled as second (parabola), fourth, or higher even-degree power functions. The
surface (1.371) and equatorial (1.418) refractive index were assumed to be independent
of age. At the lens surface, the isoindicial curvatures were equal to the lens surface
curvature. The equatorial isoindicial curvature was adjusted until the power of the
lens model matched measurements on isolated lenses of age 20 (32D) and 40 years
(24D) (Borja et al, ARVO 06).
Results: The contribution of the gradient to lens power is dependent only on the
difference between the equatorial and surface values of the index (Δn) and isoindicial
curvature (ΔK), independent of the shape of the index profile. The model is consistent
with the measurements when the isoindicial curvature increases from the surfaces
to the equator. When Δn=0.047, the model matches the 20 year old lens when
ΔK=0.287mm-1 (anterior) and 0.439mm-1 (posterior) and the 40 year old lens when
ΔK=0.204mm-1 (anterior) and 0.347mm-1 (posterior).
Conclusion: A change in the axial index profile alone is not sufficient to explain the
decrease in power of the isolated lens with age. The decrease in lens power with
age is associated with a decrease in the variation the isoindicial surfaces along the
optical axis.
CR: F. Manns, None; A. Ho, None; D. Borja, None; J. Parel, None.
Support: NEI Grants: 2R01EY14225, 5F31EY15395, P30EY14801 (Center Grant); the
Florida Lions Eye Bank; the Henri and Flore Lesieur Foundation; Research to Prevent
Blindness; the Vision Cooperative Research Centre, Sydney, Australia, supported
by the Australian Federal Government through the Cooperative Research Centres
Programme.
3776 - A53
Species Variation of Human and Non-Human Primate Crystalline Lens
Refractive Index Measured With Optical Coherence Tomography
M. Dubbelman, E.A. Hermans, G.L. van der Heijde, R.M. Heethaar. Physics & Medical
Technology, Vrije Univ Medical Center, Amsterdam, The Netherlands.
Purpose: To experimentally verify the suggestion of Gullstrand (1911) hat the
equivalent refractive index of the human lens increases with accommodation.
Methods: For five subjects, the left eye was used to focus at a different accommodation
stimulus, while the right eye was imaged using corrected Scheimpflug photography in
order to obtain the shape of the lens and cornea during accommodation. Thereafter, the
procedure was repeated, but instead of the Scheimpflug imaging, the accommodative
response of the right eye was measured objectively with an aberrometer. Finally, the
axial length was measured using the Zeiss IOL-master. Combining the results of all
these measurements allowed correction of the digital Scheimpflug images for corneal
and lenticular refraction and simultaneously calculation of the equivalent refractive
index of the lens for all different accommodative stimuli. This equivalent refractive
index is based on the assumption that the lens consists of a homogeneous medium
with a single refractive index.
Results: Mean equivalent refractive index (±s.d) was 1.4345±0.008). For all five subjects,
there was no significant change in the equivalent refractive index of the lens as a
function of accommodation. Furthermore, the accommodative response appeared to
be lower than the accommodative stimulus (i.e. accommodative lag).
Conclusions: Gullstrand suggested that the change of power of the lens needed for
accommodation does not result of changes in lens thickness and surface curvature alone,
but also from changes in the refractive index distribution within the lens. As a result,
there would be an increase in the equivalent refractive index with accommodation.
He called this process the intracapsular mechanism of accommodation. However, our
results make it clear that the equivalent refractive index of the lens does not change
with accommodation when the accommodative lag is taken into account.
CR: M. Dubbelman, None; E.A. Hermans, None; G.L. van der Heijde, None; R.M.
Heethaar, None.
Support: The SenterNovem grant IS 043081
S.R. Uhlhorn1, D. Borja1,2, F. Manns1,2, J.-M. Parel1,3. 1Bascom Palmer Eye Institute,
University of Miami School of Medicine, Miami, FL; 2Department of Biomedical
Engineering, University of Miami College of Engineering, Coral Gables, FL; 3Vision
Cooperative Research Centre, Sydney, Australia.
Purpose: To determine if there are significant differences in the average refractive
index of the crystalline lens between human and non-human primates.
Methods: Human and non-human primate (NHP) (cynomolgus monkey) crystalline
lenses were isolated from whole cadaver globes (human: n=29, age range 23-82 years,
post-mortem time <4 days, NHP: n=33, age range 3-11 years, post-mortem time <1
day) and placed in a preservation media-filled chamber resting on a soft rubber
ring. Cross-sectional images of the isolated lenses were recorded with an optical
coherence tomography system. From the recorded images, the average refractive
index is calculated along the optic axis by measuring the optical thickness of the lens
and the apparent location of the sample chamber window. These 2 parameters are
used to calculate the axial thickness and group refractive index of the lens at the light
source wavelength (825nm). The average group refractive index is first converted to
the phase refractive index at 825 nm and then to the phase refractive index at 589 nm
using lens dispersion data from the literature. The measured index was then analyzed
as a function of age to determine whether any age-related differences exist.
Results: The average refractive index along the optic axis was 1.407 +/- 0.004 (n =
29) for the human lenses and 1.414 +/- 0.009 (n = 33) for the NHP lenses. A linear
regression of the human lens data as a function of age gave n = 1.414 - 0.00013*Age
(R^2 = 0.19) and for the NHP data gave n = 1.410 + 0.00036*Age (R^2 = 0.15). The very
small age coefficients and small regression coefficients (R^2) suggest there is little
age-dependence in the average refractive index of both human and NHP lenses despite
a significant decrease in the optical power with age.
Conclusions: There is little difference in the average refractive index of human and
NHP species. These results provide further evidence that cynolmolgus monkey and
other NHP species are well suited for use as an animal model for accommodation
and presbyopia research.
CR: S.R. Uhlhorn, None; D. Borja, None; F. Manns, None; J. Parel, None.
Support: R01 EY14225, P30 EY14801 (NIH Center Grant), F32 EY15362 (Kirschstein
NRSA Fellowship), F31 EY15395 (Kirschstein NRSA Fellowship), Advanced Medical
Optics, Santa Clara, CA, the Florida Lions Eye Bank, the Henri and Flore Lesieur
Foundation, an unrestricted grant from Research to Prevent Blindness, and the
Australian Federal Government CRC Scheme through the Vision Cooperative Research
Centre.
3773-3776
3777 - A54
In vivo Biometric Evaluation of Phakic and Pseudophakic Eyes During
Accommodation With Optical Coherence Tomography
3778 - A55
In situ Observation of the Human Crystalline Lens Response to Dynamic
Accommodation Across Age
L.N. Davies, G.A. Gibson, A.L. Sheppard, J.S. Wolffsohn. School of Life & Health
Sciences, Aston University, Birmingham, United Kingdom.
R.K. Zoltoski1A, E. Wyles1B, M. Burke1A, M. Mazurkiewicz2, J.R. Kuszak 2. ABasic
& Hlth Sci, BClinical Education, 1Illinois College of Optometry, Chicago, IL;
2
Ophthalmology, Rush University Medical Center, Chicago, IL.
Purpose: To investigate the relationship between refractive and anterior segment
biometric changes in phakic and pseudophakic eyes during accommodation with
Optical Coherence Tomography (OCT).
Methods: Refractive and biometric data were taken from 32 phakic human eyes (aged
18 to 36 years old; mean ± SD, 19.9 ± 3.6 years). Mean relative change in anterior chamber
depth (ACD), lens thickness (LT), lens centriod (LC = ACD + (LT/2)), anterior segment
length (ASL = ACD +LT) and in objective refraction were assessed while subjects
viewed an accommodative target between 0 D and 4 D in 1 D steps. Mean relative
change in ACD was also measured in 15 eyes implanted with the Kellen Tetraflex
KH3500 AIOL (aged 44 to 85 years old; mean ± SD, 69.4 ± 10.0 years). In both cohorts,
mean accommodative responses were measured with the Shin-Nippon NVision-K
5001 autorefractor, while biometric parameters were assessed subsequently with the
Zeiss Visante anterior segment OCT.
Results: In the phakic cohort, mean LT increased by 72.6 μm/D, ASL increased by 18.2
μm/D, while there was a mean anterior shift in LC of 18.0 μm/D. Mean ACD decreased
by 52.8 μm/D, and increased by 353.8 μm/D for the phakic and psuedophakic eyes,
respectively. The correlation between biometric changes for both accommodative
demand and response in the phakic group followed a non-linear biphasic profile.
The forward movement of the anterior crystalline lens surface was the primary
correlate to ~1.5 D response, thereafter, the backward shift in the posterior surface
also contributed to the accommodative response. The posterior shift in AIOL position
with increasing accommodative demand corresponded with the concurrent change
in refractive error.
Conclusions: The biometric and refractive changes of the human crystalline lens,
particularly the posterior lens surface, appears to be biphasic and non-linear in
function; however, this relationship with AIOLs is absent. Indeed, rather than the
proposed anterior shift, the AIOL is displaced posteriorly with accommodation.
CR: L.N. Davies, None; G.A. Gibson, None; A.L. Sheppard, None; J.S. Wolffsohn,
None.
Support: EPSRC Grant CASE/CNA/05/51
Purpose: Analysis of ex-vivo primate lenses suggests that an underlying basis for the
mechanism of accommodation is the interfacing of fibers ends at suture branches.
In an unaccommodated state, the fibers ends are arranged end to end, while during
accommodation, the fibers slide over each other and overlap to create a thicker lens.
We report results of in-situ slit-lamp analysis of human anterior suture appearance
in the accommodated vs. the unaccommodated state that is consistent with the exvivo studies.
Methods: Lenses from normal myopic subjects ranging in age from 6 to 55 (n=30) were
photographed using a Haag-Streit slit-lamp, with particular emphasis on individual
anterior suture branches, while the subjects were either not accommodating or
attempting to accommodate to a 2.5, 5, 7.5, or 10D stimulus.
Results: When accommodation was relaxed, an anterior star-like suture pattern
was visible across all ages. The number of branches increased with age, such that in
younger lenses, three suture branches were the maximum seen, while in the older
lenses, 4 or more sub-branches were visible. We were able to consistently observe a
dark band bracketed by a pair of broader diffuse bands. When accommodation was
stimulated and the subject was able to clear the image, a single more diffuse band
that approximated the size of the previously described pair of diffuse bands was
apparent. The central dark band became smaller as the accommodating stimulus
increased. The suture patterns became much more difficult to isolate at the higher
levels of accommodative stimulus in the younger subjects, as the diffuse bands of
one suture branch began to blend into the diffuse bands of the next suture branch.
In the older subjects, who were not able to clear the accommodative stimulus, there
was little change in the appearance of the suture branches during the accommodative
process.
Conclusions: The dark band was consistent with minimal scattering due to the end-toend arrangement of fiber cells at the sutures in the unaccommodated state. The more
diffuse bands were consistent with increased scattering due to the active overlap and
interfacing of fiber ends at the sutures thereby eliminating the central dark band. Using
in-situ slit-lamp analysis which was completely consistent with the ex-vivo microscopic
analysis, it may be possible to objectively determine the accommodative abilities of
a lens in-situ and assist in accommodative disorders diagnoses.
CR: R.K. Zoltoski, None; E. Wyles, None; M. Burke, None; M. Mazurkiewicz,
None; J.R. Kuszak, None.
Support: NEI Grant EY006642 to JRK and ICO RAC
3779 - A56
Volume of the Human Lens and Surface Area of the Capsular Bag During
Accommodation
3780 - A57
Long Term Effect of Antiproliferative Lens Epithelial Cell Treatment Followed
by Polymer Lens Refilling Surgery in Rabbits
E. Hermans, P.J.W. Pouwels, M. Dubbelman, J.P.A. Kuijer, R.G.L. van der Heijde, R.M.
Heethaar. Physics/Medical Technology, VU University Medical Center, Amsterdam,
The Netherlands.
R.F. Guthoff 1A, O. Stachs1A, K. Sternberg1B, T. Terwee2, K. Schmitz1B. AOphthalmology,
B
IBMT, 1University of Rostock, Rostock, Germany; 2AMO BV, Groningen, The
Netherlands.
Purpose: A change in surface area of the capsular bag or a change in lens volume,
can indicate whether the change in shape of the lens during accommodation is due
to either the compressibility or the elasticity of lens material.
Methods: 3D Magnetic Resonance Imaging (MRI) was used to undistortedly image the
complete shape of the lens in a group of five healthy subjects between the ages of 18
and 35 years. A parametric representation of the cross-sectional shape was fitted to the
edges of the lens, which were determined with a Canny edge filter. Based on a partition
of the lens into eight parts, the parametric shape allowed calculation of the crosssectional area, volume and surface area. Two accommodation stimuli were offered to
the subjects in the MRI in order to study the changes with accommodation. Corrected
Scheimpflug imaging was used to validate the results obtained with MRI.
Results: No statistical difference in central anterior and posterior radius of curvature
and thickness was found between the MRI and Scheimpflug measurements. In
accordance with the Helmholtz accommodation theory, with increasing accommodation
a reduction of anterior and posterior radius of curvature was measured. Furthermore,
a decrease of equatorial diameter and an increase of lens thickness were found. Based
on MRI, and partition of the lens into eight parts, the mean volume in the group of
five healthy subjects was 160±2.5 mm3 and the volume showed no significant change
(p=0.9) during accommodation (160±2.7 mm3). However, the mean surface area of the
capsular bag showed a significant decrease (p=0.04) during accommodation from
176±2.8 to 168±2.9 mm 2, equivalent to a mean strain of 5.0 %.
Conclusions: In the present study, the cross-sectional area of the lens increased with
accommodation but no change of lens volume was found. This implies that the internal
human lens material can be assumed to be incompressible and is undergoing elastic
deformation. Furthermore, the change in surface area indicates that the capsular bag
is also undergoing elastic deformation.
CR: E. Hermans, None; P.J.W. Pouwels, None; M. Dubbelman, None; J.P.A. Kuijer,
None; R.G.L. van der Heijde, None; R.M. Heethaar, None.
Support: Supported by the SenterNovem grant “Young eyes for elderly people” (IS
043081)
Purpose: Finding a way to prevent secondary cataract formation presents a significant
challenge in developing lens-based techniques to restore the accommodative ability
of the human eye. The objective of the long-term animal study presented here is
pharmacological intervention in polymer lens refilling surgery to prevent secondary
cataract.
Method: Polymer lens refilling surgery was performed on six eyes of 6 New Zealand
white rabbits (age 12-15 weeks). In four eyes the empty capsular bag was treated during
the surgery and after finishing phacoemulsification with an active LEC-treating
viscoelastic mixture containing Actinomycin-D (AD) + D,L-Methotrexate (MTX)
+ Sodiumhyaluronate for 5 minutes. Ultrasound biometry, slit lamp examination,
photodocumentation, and IOP measurements were performed under general
anaesthesia after 1, 3, and 6 months and, for 3 years postperatively, every third
month. The corneal endothelium was analysed by in vivo confocal laser scanning
microscopy.
Results: All eyes were successfully filled using the developed surgical procedure. No
complications occurred during wound healing. Without capsule treatment the first
signs of opacification in the ACL rabbit eye are clearly observed 2 weeks post-op. After
6 weeks opacification was already maximal. All eyes treated with the viscoelastic AD
+ MTX mixture showed no posterior capsule opacification (PCO) at 12-months postop
and no-to-low PCO 3 years postop. Some iris incarcerations were found in the plug
area. Biometric relations pre- and postoperatively corresponded to each other, and
anterior chamber depth and lens thickness were constant over the follow-up time.
Shape, number, and distribution of corneal endothelial cells, and IOP, as well as the
quality of fundus imaging were comparable before and after surgery. The animals
(age 3.5 years) are still alive for follow up.
Conclusions: The lens refilling procedure is feasible in rabbit eyes without alterations
in the cornea and anterior segment configuration. Without capsular bag treatment,
rabbit eyes showed a strong PCO development starting directly after cataract surgery.
An active LEC treatment with AD+MTX proved to be a valid method to prevent PCO
in rabbits. Our findings can be seen as a good starting point from which to proceed
with non-human primate studies.
CR: R.F. Guthoff, AMO, C; O. Stachs, AMO, C; K. Sternberg, None; T. Terwee,
AMO BV, E; K. Schmitz, AMO, F.
Support: None
3777-3780
3781 - A58
Opacification of the Capsular Bag in Primates After Polymer Lens Refilling
T. Terwee1, S. Koopmans2A, T. van Kooten2B. 1R&D, AMO Groningen, Groningen, The
Netherlands; AEye Department, BBiomedical Engineering, 2UMCG, Groningen, The
Netherlands.
Purpose: After refilling the capsular bag of a monkey eye with an injected polymer
lens refilling accommodating IOL, a capsular opacification may occur. The purpose
of this study was to demonstrate that this capsular opacification is also dependent
on the capsular filling material.
Methods: The natural lenses of 2 iridectomized rhesus monkey eyes were removed
through a 1.5 mm peripheral capsulorhexis, and the capsular bags were treated for
5 minutes with a viscoelastic solution in pure water containing Actinomycin-D.
Composition and method were selected from in vitro (human rhexis material) and
in vivo studies (rabbits) as an effective method against lens epithelial cell (LEC)
proliferation. The capsular bag of Monkey A’s left eye was filled with a silicone-based
pre-polymer mixture that cures in-situ. The capsular bag of Monkey B’s left eye was
filled with a viscoelastic sodiumhyaluronate solution (Healon OVD) and closed with
a silicone plug. After 3 months the Healon was replaced with the same silicone-based
material that was used in Monkey A. The cleanliness of the eyes was inspected with
a slit lamp and under a surgical microscope. When possible, the refraction of the
eyes was measured with a Hartinger refractometer before and after pharmacological
stimulation of accommodation. The lens thickness was measured with A-scan and
corrected for the speed of sound through the artificial lens material (1066 m/s).
Results: Three months post-operatively, slit lamp pictures in the eye of Monkey A
showed clear signs of beginning opacification. The Healon-filled capsular bag of
Monkey B showed a good lens shape and no signs of opacification three months
post-op. Within 4 weeks after replacing the Healon with silicone material traces of
opacification could already be detected and lens thickness changes after pilocarpinestimulated accommodation decreased from 0.35 mm at 1-month post-op to 0.09 mm
at 8 months post-op.
Conclusions: With Healon OVD as a capsular filling material in monkey eyes, the
LECs did not react. However, when the LECs were in contact with artificial siliconebased lens material, a kind of foreign body reaction was observed.
3782 - A59
Comparison of Optical Changes During Accommodation in Natural and
Refilled Porcine Lenses
M.A. Reilly1,2, P.D. Hamilton 3A, N. Ravi 3B,4. 1Energy, Environmental, and Chemical
Engineering, Washington University in St. Louis, Saint Louis, MO; 2Research,
Department of Veterans Affairs JC Medical Center, St. Louis, MO; AResearch,
B
Chief of Staff, 3Department of Veterans Affairs JC Medical Center, Saint Louis,
MO; 4Energy, Environmental, and Chemical Engineering, Washington University
in St. Louis, St. Louis, MO.
Purpose: To determine the efficacy of refilling the lens capsule with a homogeneous
material with properties matched with those of the natural lens.
Methods: Fresh porcine lenses were dissected, keeping the zonules and ciliary muscle
attached. The lens was fixed in an eight-arm lens stretcher by clamping on the ciliary
muscle. A slit-lamp microscope was used to image the lens in vitro from a position at
the equator, perpendicular to the optical axis. This allowed clear visualization of the
curvature of the optical zone of both lens surfaces. Radii of curvature of both surfaces
were determined as a function of applied force. The experiment was then repeated
with lenses refilled with a homogeneous hydrogel polymer.
Results: The accommodative changes of the natural and refilled lenses were markedly
different. The optical power of the natural lens decreased monotonically as equatorial
displacement increased. The optical power of the refilled lens increased slightly due
to stretching, though neither radius of curvature changed signficantly. Mechanical
modeling using local material property data found using microindentation1 indicated
that the variation in mechanical properties in the natural lens may be required for
achieving useful accommodation in lens refilling.
Conclusions: The optomechanical behavior of the lens is dependent on local
mechanical properties. Refilling the lens with a homogeneous material does not
recover useful accommodation. Mechanical modeling of the lens as a viscous or
homogeneous medium will not capture its true behavior.
Reference:
1. M. A. Reilly and N. Ravi, The Mechanical Properties of the Porcine Lens. Invest.
Ophthalmol. Vis. Sci. 2007 48: E-Abstract 2023.
CR: M.A. Reilly, None; P.D. Hamilton, None; N. Ravi, None.
Support: VA Merit Review Grant to N. Ravi; NIH P30 EY 02697
CR: T. Terwee, AMO Groningen BV, E; S. Koopmans, AMO Groningen BV, F; T. van
Kooten, AMO Groningen BV, F.
Support: Dutch Grant IS04308
3783 - A60
Injection Force of the Visiogen Synchrony Preloaded Injector
3784 - A61
Change in Lens Profile During Simulated Accommodation: The Effect of
Anterior Zonule Transection
S. Evans, G. Tsai, P. Nguyen. Visiogen, Irvine, CA.
Purpose: To evaluate the Visiogen Synchrony Preloaded Injector and determine the
average peak friction force required to deliver this dual optic accommodating IOL.
Methods: A calibrated load cell was attached to a Chatillon force tester and set to
compression mode. Fifty eight (58) Preloaded Visiogen Synchrony Injectors were
placed into a holding fixture designed to stabilize the injectors during insertion
and simulate actual use. The fixture was attached to a load cell and the plunger of
the Synchrony Injector was advanced at a rate of 6 inch/minute. The peak force of
injection was recorded using system software as a function of distance traveled.
Five IOL powers (17D (n = 10), 18D (n = 15), 20D (n = 14), 21.5D (n = 5) and 24 D (n =
14)) were evaluated.
Results: The plunger traveled smoothly down the injection barrel and all lenses
were delivered without damage. An initial peak force was recorded that represents
the force required to overcome static friction and then the force profile decreased to
a constant dynamic friction force as the single piece silicone dual optic IOL traveled
down the injector nozzle. The mean ± SD peak injection force for all units tested was
0.32 ± 0.17lbs. The mean ± SD peak injection force by diopter group was 0.27 ± 0.14
lbs (17D), 0.27 ± 0.17 lbs (18D), 0.45 ± 0.21 lbs (20D), 0.29 ±0.04 lbs (21.5D) and 0.30 ±
0.11 lbs (24D).
Since the number of samples was different between IOL powers, a balanced ANOVA
was performed considering five randomly picked samples for each IOL power. There
was no significant difference between the forces recorded for the various IOL powers
(p = 0.59).
Conclusions: The Preloaded Visiogen Synchrony IOL Inserter successfully delivered
fifty eight (58) dual optic lenses. The average peak force recorded is similar to the
forces that have been attributed to other injection systems and did not vary with
lens diopter power.
CR: S. Evans, Visiogen, E; G. Tsai, Visiogen, E; P. Nguyen, Visiogen, E.
Support: None
D. Nankivil1,2, D. Borja1,2, K. Ehrmann 3,4, S. Uhlhorn1, E. Arrieta-Quintero1, A. Ho3,4, F.
Manns1,2, J.-M. Parel1,3. 1Ophthalmic Biophysics Center, Bascom Palmer Eye Institute,
University of Miami Miller School of Medicine, Miami, FL; 2Biomedical Optics and
Laser Laboratory, Department of Biomedical Engineering, University of Miami
College of Engineering, Coral Gables, FL; 3Vision Cooperative Research Center,
Sydney, Australia; 4Institute for Eye Research, Sydney, Australia.
Purpose: To quantify the role of anterior zonular tension on the lens radius of curvature
during simulation of accommodation in a lens stretcher.
Methods: One post-mortem cynomolgus monkey eye (7 year old) was dissected
leaving intact the lens, zonules, ciliary body, hyaloid membrane, anterior vitreous
and a segmented scleral rim. The lens preparation was mounted in an optomechanical
lens stretching system (EVAS II, Ehrmann et al, SPIE Proceedings Vol 5314) and the
sclera was stretched 3mm radially in a step-wise fashion (0.5mm/step). The load was
recorded at each step, as well as images of the entire crystalline lens acquired using a
custom-made Optical Coherence Tomography (OCT) system. The OCT images were
processed to calculate the anterior and posterior radii of curvature of the lens at each
step. The anterior zonular fibers were then carefully transected using a diamond blade
and the experiment was repeated. The changes in the radii-load relationship before
and after transection of the zonules were compared.
Results: Stretching increased the anterior and posterior radius of curvature of the lens
by 9.44±0.17mm and 1.34±0.04mm before zonular transection and 4.09±0.07mm and
1.92±0.04mm after zonular transection. The radius of the anterior surface increased
linearly as the load increased, with a slope of 2.57±0.36mm/g before and 1.58±0.25mm/g
after zonular transection. Similarly, the radius of curvature of the posterior surface
increased with a slope of 0.39±0.06mm/g before and 0.76±0.08mm/g after zonular
transection.
Conclusion: The posterior zonules, hyaloid membrane and anterior vitreous, contribute
significantly to the changes in both anterior and posterior lens shape.
CR: D. Nankivil, None; D. Borja, None; K. Ehrmann, None; S. Uhlhorn, None; E.
Arrieta-Quintero, None; A. Ho, None; F. Manns, None; J. Parel, None.
Support: NIH Grants 2R01EY1422; 5F31EY15395 (NRSA Individual Predoctoral
Fellowship); the Florida Lions Eye Bank; P30EY14801 (Center Grant); an unrestricted
grant from Research to Prevent Blindness; the Vision Cooperative Research Centre,
Sydney, New South Wales, Australia, supported by the Australian Federal Government
through the Cooperative Research Centres Programme and the Henri and Flore
Lesieur Foundation.
3781-3784
3785 - A62
Measurement of Lens Stiffness Using a Spinning Lens Test
3786 - A63
Nonlinear Optical Interactions in the Crystalline Lens and Implications for a
Presbyopia Cure
G.S. Wilde1A, S.J. Judge1B, H.J. Burd1A. AEngineering Science, BPhysiology, Anatomy
and Genetics, 1University of Oxford, Oxford, United Kingdom.
Purpose: To collect new data on the stiffness of the human lens using an improved
form of the spinning lens test originally developed by Fisher (1971), and to investigate
the causes of differences between Fisher’s original stiffness measurements and the
results of more recent tests using indentation methods (Heys 2004; Weeber 2007).
Methods: Lens spinning tests were performed using a custom-built rig. Digital images
of the lens were acquired with a 6 megapixel DSLR camera. Exposure was controlled by
a short duration flash triggered electronically to capture eight equally-spaced angular
orientations. Initially, each lens was tested with the capsule intact. Subsequently, the
capsule was removed and the test was repeated. Tests were conducted at rotational
speeds of 700 and 1000rpm. Reference images of the lens, rotating slowly, were captured
before and after each test. A hyperelastic finite element inverse analysis was used to
compute values of shear modulus for each lens. Each inverse analysis was based on
an axisymmetric mesh generated on the average outline obtained from the images
of the slowly rotating lens. Several models for the spatial variation of shear modulus
within the lens were investigated.
Results: The equatorial displacements of encapsulated lenses spun at 1000rpm declined
with age from around 0.07mm in the third decade of life to less than 0.01mm by the
seventh; the corresponding axial thickness changes were approximately 0.24mm
and 0.04mm. Deformations in the decapsulated lenses were systematically greater
than those in the encapsulated lenses. The lenses exhibited irreversible deformations
after spinning at 700 and 1000rpm; these were more pronounced in the decapsulated
lenses. A typical result from the inverse analysis for a 23 year-old decapsulated lens,
assuming material homogeneity, suggested a shear modulus of 0.3kPa.
Conclusions: Equatorial and polar displacements measured for encapsulated lenses
are broadly consistent with those reported by Fisher (1971). On the other hand,
initial results indicate that the presence of the capsule has an important effect on the
deformations generated in the spinning lens test, in contrast to Fisher’s assertion that
the capsule has only a minor effect.
CR: G.S. Wilde, None; S.J. Judge, None; H.J. Burd, None.
Support: Wellcome Trust, Leverhulme Trust
3787 - A64
Topical Pilocarpine Stimulated Accommodation in Anesthetized Rhesus
Monkeys
L.G. Epps1A, R. Sharma1A, Y. Mirchandani1A, M.L. Kisilak1B, J. Sanderson1A,2, Q.-B.
Lu1A,2, D. Strickland1A,2, M.C.W. Campbell1B,2. APhysics and Astronomy, BPhysics &
Astronomy/School of Optometry, 1University of Waterloo, Waterloo, ON, Canada;
2
Guelph-Waterloo Physics Institute, Waterloo, ON, Canada.
Purpose: Micromachining the crystalline lens of the eye with infrared (IR) femtosecond
laser pulses has been proposed as a “cure” for presbyopia. It has previously been
predicted that the gradient refractive index (GRIN) lens structure may produce
self-focusing in the crystalline lens at powers lower than in homogeneous media.
We wished to investigate the thresholds for creation of visible light in the crystalline
lens from short infrared pulses, as a signature of the possible underlying nonlinear
processes including self focusing and fluorescence from multiphoton absorption or
ionization.
Methods: We focused femtosecond IR lasers of different pulse widths through
different powered lenses into a small cell of water or saline. We recorded the power
level at which white light was first observed by the naked eye on a card placed behind
the cell. We then placed an in vitro crystalline lens (4 bovine and 4 human) into the cell
so that the light focus was within the lens. We determined the power level at which
white light was seen from above, as a beam through the lens, and when flashes were
observed on the card. We recorded the light, visible from above with a cooled camera
fitted with an IR blocking filter.
Results: White light was transmitted through bovine lenses at energies slightly below
the threshold for its production in water. In the human lens, white light was seen
from above but was not transmitted through the lens. This occurred at energies up
to a factor of 8 below the appearance of white light in water.
Conclusions: Production of visible light in crystalline lenses from femtosecond pulses
is species dependent. The GRIN in the bovine lens appears to lower the threshold for
self-focusing below that for water. In the human lens, it appears that either multiphoton
absorption or multiphoton ionization results in fluorescence at power levels below
those for self-focusing. When studying the interaction of femtosecond laser pulses with
the crystalline lens, more than one multiphoton process needs to be considered.
CR: L.G. Epps, None; R. Sharma, None; Y. Mirchandani, None; M.L. Kisilak, None; J.
Sanderson, None; Q. Lu, None; D. Strickland, None; M.C.W. Campbell, N/A, P.
Support: NSERC Canada, Ontario Photonics Consortium
3788 - A65
Mechanical Properties of the Porcine Lens Capsule
M. Wendt, A. Glasser. College of Optometry, University of Houston, Houston, TX.
Purpose: Many studies have used topically administered pilocarpine to stimulate
accommodation in both humans and monkeys. However, the concentrations of
pilocarpine used and the methods of administration have varied. In this study,
different concentrations of pilocarpine eye drops were tested for their effectiveness
in stimulating accommodation in rhesus monkeys.
Methods: Iridectomized eyes were studied in 14 anesthetized rhesus monkeys aged
5 to 16 years. Maximum accommodation was stimulated in all these monkeys with a
2% pilocarpine solution maintained on the cornea for at least 30 minutes in a specially
designed perfusion lens. In subsequent topical pilocarpine experiments, baseline
refraction was measured with a Hartinger coincidence refractometer. While upright
and facing forward, commercially available pilocarpine (2, 4, or 6 %) was applied to the
surface of the cornea using a pipetter in volumes of either 25 μl (1 drop) or 50 μl (2 drops).
Monkeys received 2 or 4 drops in two applications or 6 drops in three applications over
a five minute period with the eyelids closed between applications. Alternatively, while
supine, 10-12 drops of pilocarpine were maintained on the cornea in a scleral cup for
five minutes. After pilocarpine administration, the eyelids remained closed except
for brief periods when they were opened for refraction measurements. Refraction
measurements were begun five minutes after the second application of pilocarpine.
Measurements continued for at least 30 minutes after initial administration until no
further change in refraction occurred.
Results: Constant 2% pilocarpine solution on the eye in the perfusion lens produced
10.88 ± 2.73 (mean ± SD). The results of topically applied pilocarpine were 3.81 D ±
2.41, 5.49 D ± 4.08, and 5.55 D ± 3.27 using 2%, 4%, and 6% solutions respectively. When
expressed as a percentage of the accommodative response amplitude obtained in the
same monkey with constant 2% pilocarpine solution on the eye, the responses were
34.7% for 2% pilocarpine, 48.4% for 4% pilocarpine, and 44.6% for 6% pilocarpine.
Topical 4% and 6% pilocarpine achieved similar accommodative responses, but neither
achieved maximum accommodation.
Conclusions: Considerable variability in response amplitude occurred and maximum
accommodative amplitude was rarely achieved with topical application of a variety
of concentrations of commercially available pilocarpine. Although widely used as a
simple procedure for stimulating accommodation, topical application of commercial
pilocarpine solutions appears to be a remarkably unreliable method for stimulating
accommodation in rhesus monkeys.
CR: M. Wendt, None; A. Glasser, None.
Support: NEI grant RO1 EY014651 TO AG
R. Amini1A, A. Oltean1A, V.A. Barnett1B, Y. Segal2, V.H. Barocas1A. ADept of Biomedical
Engineering, BDept of Integrative Biology and Physiology, 1University of
Minnesota, Minneapolis, MN; 2Dept of Medicine, University of Minnesota and
Minneapolis VA Medical Center, Minneapolis, MN.
Purpose:To use osmotic swelling as a driving force to measure the elasticity of the
porcine lens capsule.
Methods:We developed a simple model to simulate the swelling lens as a lumped
system, accounting for the permeability of the membrane to the solvent, the osmotic
pressure inside the lens, and the elasticity of the capsule. Porcine lenses were submerged
in pure H2O, 0.2% and 0.5% saline solutions. Sequential images taken during osmotic
swelling were captured and analyzed in MATLAB. Fitting the experimental data to
the model provided an estimate of the elasticity of the lens capsule.
Results:The calculated modulus was 0.21 ± 0.08 MPa for pure H2O (n = 7), 0.24± 0.06
MPa for 0.2% saline solution (n = 7), and 0.15± 0.04 MPa for 0.5% saline (n = 7) solution.
The difference in these values were not statistically significant when pure H2O was
compared with 0.2% saline solution (p = 0.37) and 0.5% saline solution (p = 0.10).
Conclusions:Our experimental model provides an estimation of the modulus of
elasticity of the porcine lens capsule without requiring dissection of the lens. Estimated
values of the modulus are within the range of those obtained by other methods
(Krag and Andreassen, Exp Eye Res 62:253-60, 1996; Heistand et al., Biomech Model
Mechanobiol., 4(2-3):168-77, 2005).The new method could be employed in smaller
animals, such as mice, for which conventional mechanical stretching methods are
not practical.
CR: R. Amini, None; A. Oltean, None; V.A. Barnett, None; Y. Segal, None; V.H.
Barocas, None.
Support: NIH 1 R01 EY15795-01
3785-3788
3789 - A66
Light Transmission Characteristics of the Human Lens as a Function of Age
M.K. Hartzer, A. Akinay, M. Ong, A. Heath-Cobb, D. Jinkerson, J. Weinschenk, J.
Menczel, M. Karakelle. Surgical Products Research, Alcon Laboratories, Fort Worth,
TX.
3790 - A67
Compact Scheiner System for Optical Power Assessment of ex vivo Crystalline
Lenses
S.M. Delgado1,2, F. Manns1,2, W. Lee1, I. Nose1, A. Amelinckx1, E. Arrieta-Quintero1, D.
Nankivil1,2, D. Borja1,2, R. Jain 3, J.-M. Parel1,4. 1Ophthalmic Biophysics Center, Bascom
Palmer Eye Institute, University of Miami Miller School of Medicine, Miami,
FL; 2Biomedical Optics and Laser Laboratory Dept of Biomedical Engineering,
University of Miami, College of Engineering, Coral Gables, FL; 3AMO Inc, Santa
Ana, CA; 4Vision Cooperative Research Centre, Sydney, Australia.
Purpose: Limited information is available on how transmission of visible light changes
with the age of the human crystalline lens (HCL). Therefore, a UV/Visible spectroscopic
method was developed to determine light transmission characteristics of excised
HCLs of various ages.
Methods: HCLs (2-7 days post-mortem) stored in Optisol-GS or Eusol-C media were
received from eye banks and visually examined for opacity. Lenses were positioned on
a printed background with the anterior surface facing up, examined under a dissection
microscope and photographed. Afterwards, the HCLs were submersed in BSS®, and
cross-sectional scans for opacities were performed with a non-contact high frequency
(45-60 MHz) ultrasound biomicroscope at various focal planes. Only HCLs with
transparent central 5-6 mm zones were used, which were then stored in phenol-red free
Eusol-C. Samples were placed in a quartz cell-HCL holder assembly, which was filled
with BSS. The UV/Vis transmission analysis was carried out in the wavelength range
850-300 nm using a Perkin-Elmer Lambda 35 UV/Vis spectrophotometer equipped
with a Lab Sphere RSE-PE-20 integrating sphere. HCLs in age groups (yrs): 10-19 (8
HCLs from 4 donors), 20-29 (8 HCLs from 4 donors), 30-39 (8 HCLs from 4 donors)
and 40-49 (12 HCLs from 6 donors) were evaluated. Composite spectra were built
for each age range.
Results: In contrast to previous studies, efforts were made in our study to minimize
artifacts during light transmission measurements of human lenses. The lenses were
prescreened for opacities. They were stored and measured in appropriate physiological
media, which minimizes artifacts from Fresnel reflections. In addition, the lenses
were not compressed in order to minimize artifacts such as opacification and allow
the light transmission characteristics of the lens to be measured in its natural state.
For longer visible light wavelengths (850-600 nm), high transmittance values (~95%)
were measured for all HCLs. However, with increasing age a significant reduction
in light transmission was seen in the visible blue light range (500-420 nm). Cut-off
wavelength (410 nm) was the same for all ages.
Conclusions: This study utilizes a novel method for measuring light transmission of
HCLs with minimal introduction of artifacts.
CR: M.K. Hartzer, Alcon Laboratories Ltd., E; A. Akinay, Alcon Laboratories Ltd.,
E; M. Ong, Alcon Laboratories Ltd., E; A. Heath-Cobb, Alcon Laboratories Ltd., E; D.
Jinkerson, Alcon Laboratories Ltd., E; J. Weinschenk, Alcon Laboratories Ltd., E; J.
Menczel, Alcon Laboratories Ltd., E; M. Karakelle, Alcon Laboratories Ltd., E.
Support: None
Purpose: To measure the refractive power of ex vivo animal crystalline lenses using
a compact, portable Scheiner system.
Methods: The beam of a 635nm laser diode is transmitted thru a multimode fiber to
an infinity collimator and an opaque disc with four optically centered equidistant
pinholes (200um dia at 2 or 3mm center-to-center) mounted 240mm above a stand
holding the prepared crystalline lens sample which is immersed in a Petri dish filled
with DMEM. A CCD mounted on the measuring arm of a digital vernier (#570-244
Mitutoyo, Tokyo, Japan) permits visualization of the four converging beams. The focal
length of the sample lens is determined by finding the intersection point of the four
beams. The system was calibrated in air using a set of glass lenses of back focal lengths
ranging from 12.03 to 70.42mm (Edmund Optics). Enucleated whole eyes were bonded
to a plastic ring using cyanoacrylate adhesive and dissected leaving a transverse
anterior section containing the crystalline lens, zonular apparatus, ciliary body and a
scleral rim attached to the ring. The refractive power of 3 human (range 55-60 years, <3
days postmortem), 7 cynomolgus (range 3-9years, <1 day postmortem) and 1 baboon
(5 years old, 3hrs postmortem) lenses were measured three times each.
Results: The accuracy and precision of the Scheiner system evaluated on the glass
lenses ranged from -0.60+/-0.2D to +1.12+/-0.57D. Refractive powers of natural lenses
were: human: 21.71+/- 0.39D to 23.14+/-0.18D, cynomolgus: 49.40+/-0.78D to 55.03D+/0.65D and baboon: 43.53+/-1.25D.
Conclusions: The portable Scheiner system allows rapid and precise dioptric power
determination of human and animal ex vivo lenses supported by an intact zonular
framework.
CR: S.M. Delgado, None; F. Manns, None; W. Lee, None; I. Nose, None; A. Amelinckx,
None; E. Arrieta-Quintero, None; D. Nankivil, None; D. Borja, None; R. Jain, AMO,
E; J. Parel, F, F.
Support: NIH: 2R01EY14225, 5F31EY15395, P30EY14801 (Center Grant); the Florida
Lions Eye Bank; Advanced Medical Optics Inc, Santa Ana, CA; an unrestricted grant
from Research to Prevent Blindness; the Australian Federal Government CRC Scheme
through the Vision Cooperative Research Centre, Sydney Australia; Henri and Flore
Lesieur Foundation.
3791 - A68
Model of the Isolated Human Crystalline Lens Shape Using Polynomial
Functions
3792 - A69
EVAS II: Advanced Lens Stretcher to Determine Accommodation Forces vs.
Power and Geometry
R. Urs1,2, D. Borja1,2, A. Amelinckx1, J. Smith1,2, R. Augusteyn3, F. Manns1,2, J.-M. Parel1,3.
1
Ophthalmic Biophysics Center, Bascom Palmer Eye Institute, University of Miami
Miller School of Medicine, Miami, FL; 2Biomedical Optics and Laser Laboratory,
Dept of Biomedical Engineering, University of Miami College of Engineering,
Coral Gables, FL; 3Vision Cooperative Research Centre, Sydney, Australia.
K. Ehrmann1A,2, A. Ho1A,2, E. Arrieta-Quintero3, A. Amelickx3, D. Nankivil3, D. Borja 3, N.
Ziebarth 3, J.-M. Parel3,1. AIER, 1Vision CRC, Sydney, Australia; 2Sovs, University of
New South Wales, Sydney, Australia; 3OBC, BPEI, University of Miami, Miami, FL.
Purpose: To develop an age dependent mathematical model of the isolated ex-vivo
human crystalline lens shape for use in finite element modeling.
Methods: Profiles of whole isolated human lenses (n=22) aged 26 to 82, were measured
from shadow-photographs and fit to tenth order polynomials. Two methods were
used to analyze the lenses. The Two Curves Method (TCM) used separate equations
for the anterior and posterior surfaces of the lens. The One Curve Method (OCM)
assumed symmetry around the optical axis and fit half of the contour of the lens. The
age dependence of the polynomial coefficients was assessed. The analysis was used
to produce an age-dependent polynomial model of the whole lens shape.
Results: The root mean squared errors for the fits ranged from 41 to 122 μm for the
OCM, 8 to 30 μm for the posterior surface of the TCM and 11 to 41 μm for the anterior
surface of the TCM. Coefficients of the first, fifth and ninth term of the anterior surface
of the TCM decreased with age. Coefficients of the third and seventh terms of the
anterior surface and the eight term of the posterior surface increased with age. The
coefficients of all other terms did not show any significant trend with age. The age
dependent equation of the OCM provides a reliable model from age 20 to 70.
Conclusions: The shape of the whole human crystalline lens can be accurately modeled
with tenth order polynomial functions. This model can serve to improve FE-models
of the lens.
CR: R. Urs, None; D. Borja, None; A. Amelinckx, None; J. Smith, None; R. Augusteyn,
None; F. Manns, None; J. Parel, None.
Support: NIH Grants 2R01EY14225, 5F31EY15395 (Borja), P30EY14801 (Center Grant);
the Florida Lions Eye Bank; AMO Inc, Santa Ana, CA; an unrestricted grant from
Research to Prevent Blindness; Australian Federal Government CRC Scheme through
the Vision Cooperative Research; Henri and Flore Lesieur Foundation.
Purpose: To develop and validate a method and instrument to simulate and quantify
the accommodation mechanism in the primate eye.
Methods: The newly developed ex-vivo accommodation simulator (EVAS II) stretches
the crystalline lens under controlled conditions while obtaining quantitative data on
stretching load, optical power and lens diameter changes. It also includes features
to determine anterior and posterior lens shape, lens thickness and axial motion and
ciliary body motion, using coaxial imaging, OCT (Uhlhorn, ARVO 2007), Scheimpflug
(Borja D, UM PhD proposal 2007) and 35-50MHz UBM technologies. A section of the
globe containing intact crystalline lens, zonules, ciliary muscle and a segmented
sclera is bonded to 8 curved shoes. The shoes are magnetically coupled to computer
controlled actuators, pulling the 8 segments radially in 0.5 mm diameter increments
to a maximum of 4 mm diameter change. At each step of the stretch and release
cycle, measurement data and images are automatically recorded for later analysis.
The optomechanical properties of 3 human (48 to 71 years old) and 3 cynomolgus
monkey (4 to 8 years old) eyes have been assessed thus far.
Results: The 3 human eyes were all presbyopic and no change in lens power and
diameter was observed. The total zonular stretching force reached 30.4 to 52.0 mN
(0.9 to 3.4 mN STDEV). For the 3 pre-presbyopic monkey eyes, a change in lens power
of 9.1, 9.4 and 10.1 diopters was measured, which was associated with a lens diameter
increase of 0.50, 0.58 and 0.65 mm and a force increase of 29.2, 31.1 and 34.7 mN
respectively. There was minimal hysteresis in lens diameter change between the
stretch and release cycle (mean: 0.007mm, STDEV: 0.024 mm). Although, both force
and diameter increased exponentially with pulling distance, the ratios for diameter
per diopter change and the force per diopter change were relatively constant over
the stretch distance (0.06 mm/D and 3.33 mN/D respectively). These results compare
well with published data (Manns et al, IOVS 2007).
Conclusions: The new instrument generates reliable optical, geometrical and
mechanical measurements for ex-vivo simulated accommodation. The results from
human and non-human primate eyes are consistent with the Helmholtz theory of
accommodation.
CR: K. Ehrmann, None; A. Ho, None; E. Arrieta-Quintero, None; A. Amelickx,
None; D. Nankivil, None; D. Borja, None; N. Ziebarth, None; J. Parel, None.
Support: 2R01EY14225, The Vision Cooperative Research Centre, Australia, supported
by the Australian Federal Government , Florida Lions Eye Bank; P30EY14801 (Center
Grant); Henri and Flore Lesieur Foundation
3789-3792
3793 - A70
Relationship Between Elasticity and Dioptric Power of Whole Cadaver Primate
Crystalline Lenses
N.M. Ziebarth1A,2, D. Borja1A,2, F. Manns1A,2, V.T. Moy1B, J.-M. Parel1A,3. AOphthalmic
Biophysics Center, Bascom Palmer Eye Institute, BPhysiology and Biophysics, 1Univ
of Miami Miller School of Medicine, Miami, FL; 2Biomedical Engineering, Univ of
Miami, Coral Gables, FL; 3VisionCRC, Sydney, Australia.
Purpose: To determine the relationship between primate whole lens elasticity
measured by atomic force microscopy (AFM) and dioptric power.
Methods: Measurements were performed on intact lenses of 23 non-fixed cynomolgus
eyes (4-10 years, <1 day postmortem) and 4 human eyes (26-82 years, <3 days
postmortem) that were left attached to the zonule-ciliary body-sclera framework.
The eyes were prepared by bonding a plastic ring on the sclera after removal of
conjunctiva, adipose, and muscle tissues. The posterior pole was sectioned and
excess vitreous was removed. The anterior vitreous and hyaloid membrane were
left intact. The eye’s anterior section was placed on a Teflon slide and the cornea and
iris were removed. The lens-zonule-ciliary body-sclera section was then placed in
a Petri dish filled with DMEM in a laboratory-built AFM system designed for force
measurements (Ziebarth et al, Mol Vis, 2007). The central pole of the anterior lens
surface was probed with the AFM. The recorded deflection-indentation curves were
used to derive force-indentation curves. Young’s modulus was calculated from the
force-indentation relation using the model of Hertz (Timoshenko, Theory of Elasticity
1934). After elasticity measurements, the dioptric power of the lens was measured
using a modified commercial lensmeter.
Results: Young’s modulus ranged from 0.4kPa-2.9kPa for monkey eyes and 0.8kPa29.4MPa for human eyes. Young’s modulus was not dependent on age in monkey eyes
(p=0.26), although this relationship was significant in human eyes (p=0.06). Dioptric
lens power ranged from 39.8-52.1D for monkey and 16.8-26.8D for human. Power
decreased significantly in both monkey and human lenses as age (p=0.023 and p=0.057,
respectively), and Young’s modulus increased (p=0.09 and 0.23, respectively).
Conclusions: There a direct relation between the lens power in its maximally
accommodated state (isolated lens) and lens elasticity. As Young’s modulus of the
lens increases, its maximally accommodated power decreases.
CR: N.M. Ziebarth, None; D. Borja, None; F. Manns, None; V.T. Moy, None; J.
Parel, F, F.
Support: NIH 2R01EY14225; NSF Graduate Student Fellowship; NIH 5F31EY15395;
Florida Lions Eye Bank; the Australian Federal Government CRC Scheme through
the Vision Cooperative Research Centre; AMO Inc, Santa Ana, CA; NIH center grant
P30-EY014801; Research to Prevent Blindness; Henri and Flore Lesieur Foundation;
NSF-BITC; NIH GM55611; Scientific Advisory Committee, University of Miami.
3795 - A72
Could Cortical Cataracts Be Induced By Accommodation Forces?
3794 - A71
New Method to Measure Iol- Loops Under Shrinkage of the Capsular Bag
E.H. Roth, C.G. Hoffmann. Institute Physiological Optics, Dusseldorf, Germany.
Purpose: Capsular bag shrinkage after in-the-bag implantation may result in vertical
displacement of the IOL due to compression of the IOL-loops that causes a new
topography of the whole lens. There have been few approaches to average out the
given capsular bag shrinkage by designing the IOL in a way, so that the compression
is absorbed in the initial plane of the lens. A measurement device was build to show
how the IOL- loops compressed after the shrinking of the capsular bag.
Methods: The ISO 11979-3:2006 (ophthalmic implants part 3: mechanical properties
and test methods) describes methods of observation of changes of the IOL due to
compression of IOL- loops to diameter of 10 mm. These methods are suited for the
measurement of forces and movements of the IOL, but they give no information about
these conditions, under the 10mm range.
Reciprocal effects between IOL- loops and capsular bag can’t be observed with this
method. A new vacuum chamber technique was designed to show how the IOL loops
act in a simulated capsular bag, while the bag shrinks from 12mm to 8mm.
For the simulated capsular bag we use a latex-bag 50mm long and 8mm in diameter
closed at one side. This bag is placed in a cylindrical glass vacuum chamber with an
inner diameter of 12mm. With pressure applied to the vacuum chamber the diameter
of the bag is controlled.
The procedure is captured by a video camera and the pictures evaluated by a computer
program.
Results: Holes or other defects in the IOL- loops of one-piece-lenses seem to have a
bumper- effect at the beginning of the compression, but result mainly in the same
structure as those without them do. Old fashioned three-piece-lenses (PMMA or
Acrylat) have a very stable behavior compared to one-piece-Silicon-lenses.
CR: E.H. Roth, None; C.G. Hoffmann, None.
Support: None
3796 - A73
Femtosecond Lentotomy: Retinal Changes After Treatment of the Crystalline
Lens With a 100 Khz Femtosecond Laser in Rabbits
R. Michael1, R.I. Barraquer1, B. Willekens2, J. van Marle3, G.F.J.M. Vrensen4.
1
Institut Universitari Barraquer, Barcelona, Spain; 2The Netherlands Institute
for Neuroscience, Amsterdam, The Netherlands; 3Academic Medical Center,
University of Amsterdam, Amsterdam, The Netherlands; 4Leiden University
Medical Center, Leiden, The Netherlands.
Purpose: Evaluation of the gross morphology, the location and the fiber cell architecture
of cortical opacities in the aging human lens.
Methods: Altogether, 39 human donor lenses in the age range of 55-90 years with
small focal opacities and cuneiform or spoke cataracts were obtained from the
Corneabank Amsterdam. They were photographed in toto in frontal view using darkfield stereomicroscopy. Fifteen lenses were fixed, cut in axial slices and photographed
the same way. Details of fiber cell architecture were investigated by fluorescent staining
for membranes and by scanning electron microscopy.
Results: Small focal and cuneiform cortical cataracts are discrete opacities located
at a specific depth below the capsule, and extending from the equatorial region in
anterior and posterior direction. When measured equatorially, the most superficial
part of the cuneiform opacities is at a mean depth of 510 µm below the capsule. A sharp
border is observed, between the opacities with their disorganized fiber architecture
and the transparent more superficial cortical and deeper nuclear layers, which show
a regular fiber pattern. This border is at a mean depth of 700 µm below the capsular
surface. No significant relationship is found between this depth and donor age. Close
examination of the opacities revealed fiber folds, fiber undulations, fiber-to-fiber
separations, fiber breaks, water lakes and fiber displacement.
Conclusions: Small cortical and cuneiform opacities are accompanied by changes
in fiber structure and architecture mainly in the equatorial border zone between
the lens nucleus and cortex. Because the lens cortex and nucleus have different
viscoelastic properties in young and old lenses, we hypothesize that external forces
during accommodation cause shear stress predominantly in this border zone. The
location of the described changes suggests that these mechanical forces may cause
fiber disorganization, small cortical opacities, and, ultimately, cuneiform cataracts.
CR: R. Michael, None; R.I. Barraquer, None; B. Willekens, None; J. van Marle,
None; G.F.J.M. Vrensen, None.
Support: None
U. Oberheide1, S. Schumacher2, P. Bock 3, I. Imbschweiler3, M. Fromm2, A. Wegener4,
G. Gerten1, A. Beineke3, H. Lubatschowski2. 1Laserforum EV, Cologne, Germany;
2
Laser Zentrum Hannover e.V., Hannover, Germany; 3Institut fuer Pathologie,
Tierärztliche Hochschule Hannover, Hannover, Germany; 4Augenklinik der
Universität Bonn, Bonn, Germany.
Purpose: One concept of regaining the elasticity of the lens material is the treatment
of the lens by femtosecond laser pulses (femtosecond lentotomy). However the effect
of the femtosecond laser pulses on retinal structures is only well investigated for
corneal treatment.
Our aim was to evaluate changes of the retinal layers after treatment of the crystalline
lens in rabbits with high repetition femtosecond lasers.
Methods: We used an IMRA µJewel femtosecond laser with 100 kHz repetition rate
to create microincisions in crystalline lenses of 10 rabbit eyes in vivo. Only one eye
was treated leaving the other as control.
The eyes were examined by histology (HE staining) to evaluate the influence of the
femtosecond laser pulses on the retina as side effect of the treatment.
Results: The histological examination reveals no degenerative or inflammatory
changes of the retina. No thermal alterations of retinal layers due to the laser treatment
are visible in the histological sections.
Conclusions: These preliminary results show that treating the crystalline lens with
femtosecond laser pulses does not have harmful side effects on retinal structures.
Therefore concerning retinal safety femtosecond lentotomy might be a reasonable
tool for treatment of the crystalline lens.
CR: U. Oberheide, Patent application, P; S. Schumacher, None; P. Bock, None; I.
Imbschweiler, None; M. Fromm, None; A. Wegener, None; G. Gerten, None; A.
Beineke, None; H. Lubatschowski, Patent application, P.
Support: BMBF FKZ: 13N8709
3793-3796
3797 - A74
Optical and Mechanical Properties of Animal Lenses After Fs-Laser Treatment
R. Ackermann, R. Kammel, T. Thiele, D. Wagner, S. Nolte, A. Tünnermann. Institute of
Applied Physics, Friedrich-Schiller-Universitaet Jena, Jena, Germany.
Purpose: It is commonly accepted that one of the most contributing factors for
presbyopia is the hardening of the nucleus of the crystalline lens. We show that the
flexibility of the lens can be partially restored on a physiologically relevant scale by
the application of ultrashort laser pulses.
Methods: Porcine and sheep eyes of different age were dissected within 48 hours
post-mortem by extracting the lens within the ciliary body, which was then attached
to the clamps of a lens stretching apparatus. It provides eight radial arranged arms
in order to exert and measure forces to the ciliary body with a resolution of 1 mN.
The lenses were kept in tap water or physiological saline to avoid drying. The laser
effect was evaluated by comparing a laser structured with an untreated lens of the
same individual.
The laser system provides pulses with a duration of 400 fs with an energy of up to
5 µJ at 200 kHz. A downstream scanner system allows writing three dimensional
structures with a focal spot size of about 7 µm. For a first appraisal of our method,
the whole lens nucleus was filled with a simple cubic structure, neglecting issues of
eye safety and remaining lens transmission.
For the evaluation of the lens geometry a rotating Scheimpflug-camera was used
that allowed to measure the lens shape as a function of the applied forces. Optical
characterization is performed by measuring the transmitted wave-front during the
simulated accommodation, using a common Shack-Hartmann sensor.
Results: The analysis of the forces on the ciliary body shows a reproducible range
with a linear force response, e.g. ranging to a maximum average force per clamp of
140 mN for young porcine eyes.
Both untreated and laser structured porcine lenses show a maximum increase of
the diameter which is less than 10 %. Yet, in the regime of linear force response this
increase is significantly steeper for lasered eyes.
This observation is also confirmed by the wave-front analysis. For the given setup,
porcine lenses showed a refraction power in the range of 70 - 100 dpt in the unstretched
state. In the corresponding regime of low forces the lasered eyes indicate an increased
accommodation amplitude of about 10 dpt.
Conclusions: We have developed a setup that allows to characterize the effect of
fs-laser structuring on the optical and geometrical properties of in-vitro lenses. This
establishes the basis for further investigations that will focus on an optimization of
laser structures with regard to laser safety and lens transmission.
CR: R. Ackermann, None; R. Kammel, None; T. Thiele, None; D. Wagner, None; S.
Nolte, None; A. Tünnermann, None.
Support: BMBF Grant 13N8831
3798 - A75
Femtosecond Lentotomy: Changing the Crystalline Lens Tissue by High
Repetition Rate Femtosecond Lasers
S. Schumacher1, M. Fromm1, P. Bock 2, I. Imbschweiler2, A. Beineke2, G. Gerten 3, H.
Lubatschowski1, U. Oberheide3. 1Biomedical Optics Department, Laser Zentrum
Hannover eV, Hannover, Germany; 2Institut für Pathologie, Tierärztliche
Hochschule Hannover, Hannover, Germany; 3Laserforum Köln eV, Cologne,
Germany.
Purpose: According to Helmholtz’ theory of accommodation one of the mayor reasons
for the development of presbyopia is the increasing sclerosis of the lens. One concept
of regaining the elasticity of the lens tissue is the treatment of the lens by femtosecond
laser pulses.
Methods: Our aim was to evaluate changes of crystalline lenses due to the treatment
with high repetition femtosecond lasers. We used an IMRA µJewel femtosecond laser
with 100 kHz repetition rate to create microincisions in crystalline lenses of human
autopsy eyes as well as in porcine and rabbit eyes. The treated eyes were analyzed
using OCT and histological sections for detection of the cuts. Mechanical changes
were analyzed with Fisher’s spinning test and a lens stretching device.
Results: The cuts in the crystalline lenses were detectable with OCT. Histological
sections show limited thermal and mechanical alteration of the interaction zone. The
rotation experiments as well as the lens stretching experiments show an increase in
flexibility for the treated lenses.
Conclusions: Fs-laser induced cuts in the lens lead to a gain in lens flexibility. Due to
the high repetition rate the treatment time could be decreased drastically compared
to former investigations.
CR: S. Schumacher, None; M. Fromm, None; P. Bock, None; I. Imbschweiler, None; A.
Beineke, None; G. Gerten, None; H. Lubatschowski, Inventor, P; U. Oberheide,
Inventor, P.
Support: BMBF 13N8712 and BMBF 13N8709
3799 - A76
Modulation of the Mitochondrial Function by Menadione Sodium Bisulfite
Affects Optics of the Crystalline Lens
3800 - A77
Dynamic Regulation of Microtubule Assembly by the Shsp and Molecular
Chaperone, Human αB Crystallin
K.W. Olsen, V. Bantseev, V. Choh. School of Optometry, University of Waterloo,
Waterloo, ON, Canada.
J.I. Clark1A, S. Haouck1B, J. Ghosh2. ABiological Structure and Ophthalmology,
B
Biological Structure, 1University of Washington, Seattle, WA; 2Laboratory of
Molecular Aging, Harvard Medical School, Boston, MA.
Purpose: The crystalline lens is a unique cellular organ that performs metabolic
processes while maintaining optical functionality. The mitochondria play a vital
role in providing the cell with the energy necessary for these metabolic processes.
Menadione has long been known as a cytotoxin that specifically targets mitochondria.
Upon entering the mitochondria, reactive oxygen species are formed inducing the
formation of the permeability transition pore which renders the mitochondria inactive.
The purpose of this study was to investigate the effectiveness of menadione sodium
bisulfite as a mitochondrial uncoupler in the lens and to determine the relationship
between lens metabolism and optical function.
Methods: Bovine lenses were extracted from whole bovine eyes and treated for 30
minutes at room temperature with 50 µM (n=6), 200 µM (n=4), 600 µM (n=5) and 1000
µM (n=6) menadione (w/v) in medium. A control (n=5) was treated with medium
only. Lenses were rinsed 4 times then placed in fresh culture medium. Focal lengths
of laser beams passing through the lenses at varying eccentricities were measured
at 4, 24, 48, 144, and 216 hours post-treatment. Mitochondrial activity and dynamics
were analysed using the Rhodamine 123, a mitochondria-specific marker for intact
and functioning mitochondria, and were visualised using confocal microscopy. The
images captured are analyzed using Zeiss and MATLAB software.
Results: The results show a concentration and time-dependent decrease in optical
function that became apparent as early as 24 hours after treatment with 1000 µM and
600 µM menadione treatment groups after which damage was sustained throughout
the experiment. Lenses exhibited optical degradation for 200 µM treatment group 48
hours after treatment while no change in optical function was observed for 50 µM
treatment group. Confocal microscopy images show that changes in mitochondrial
activity and dynamics precede optical changes.
Conclusions: These results show menadione to be an effective mitochondrial uncoupler
and that mitochondrial function is directly related to optical function.
CR: K.W. Olsen, None; V. Bantseev, None; V. Choh, None.
Support: NSERC Discovery Grant
Purpose: To evaluate the function of interactive sequences in human αB crystallin
on dynamic subunit exchange and microtubule assembly.
Methods: Five interactive sequences in αB crystallin were synthesized as individual
peptides for experimental studies on the assembly of microtubules in vitro using a
fluorescence DAPI assay (Ghosh et al. 2007 PloS one 6:3498). Mutations at corresponding
positions in full-length αB crystallin were used experimentally to confirm the
importance of these interactive sequences in the αB crystallin:tubulin interaction.
Results: αB crystallin inhibited microtubule assembly at molar ratios >2:1, αB
crystallin:tubulin and promoted microtubule assembly at molar ratios between
1:4 and 2:1. The plot of assembly versus molar ratio was parabolic with a maximum
at approximately 0.5:1 αB:tubulin. The synthetic peptide corresponding to the αB
crystallin interactive sequence, 113FISREFHR120, in the β3 strand of the α-crystallin
core domain partially inhibited microtubule assembly. In contrast, the peptides
LTITSSLSSDGV142 in the β8 strand and loop region of the core domain and
131
ERTIPITRE164 in the C-terminal extension promoted microtubule assembly. Mutations
156
in these exposed interactive sequences in full-length αB crystallin altered interactions
with microtubules.
Conclusion: Microtubule formation is a dynamic equilibrium and complex assembly
of the sHSP, αB crystallin, is a dynamic subunit exchange. Interactive sequences
in the core domain and C-terminal extension of αB crystallin alter the dynamic
equilibrium and/or dynamic subunit exchange to regulate complex formation and
tubulin assembly At low molar ratios of αB crystallin:tubulin, microtubule assembly
is favored and at high molar ratios the assembly of the aHSP complex is favored.
The αB crystallin:tubulin dynamic interactions may have an important role in the
development and maintenance of lens transparency.
CR: J.I. Clark, None; S. Haouck, None; J. Ghosh, None.
Support: EY04542
3797-3800
3801 - A78
Deamidations in βA3-crystallin Are Highly Correlated With Insolubulization
During Aging
T. Takata, K. Lampi. Integrative Biosci, Oregon Health & Sciences Univ, Portland, OR.
Purpose: Recently, βA3-crystallin was reported to be the most deamidated crystallin
in the insoluble proteins in aged and cataractous lenses (Wilmarth et al, 2006). Many
of the deamidation sites were detected on the surface of βA3 in vivo. The purpose of
this study was to determine the effects of reported deamidations on the surface and
in the connecting linker of βA3 in vitro.
Methods: Deamidations were mimicked on the surface of the N-terminal domain
of βA3 at Q42 and N54, on the C-terminal domain at N133 and N155, and in the
linker peptide at N120 by replacing the amides with the respective acidic residues
by site-directed mutagenesis. Far and near UV-circular dichroism, multi-angle light
scattering (MALS), quasi-elastic light scattering, size exclusion chromatography, and
analytical ultra-centrifugation were performed to characterize the structure and
formation of the dimer. The stability of proteins was investigated by measuring the
turbidity during heating and the fluorescence during unfolding/refolding in urea.
Formation of hetero-oligomers with βB1-crystallin was determined by size exclusion
chromatography with MALS and native-electrophoresis at 37 °C.
Results: All proteins folded with similar predicted secondary structure. Differences
were detected in tertiary structure particularly for N120D, N133D, and N155D. All
of the βA3- expressed proteins were predicted by analytical sedimentation and light
scattering to have very elongated elliptical structures without dimer dissociation.
Deamidation at Q42, N120, N133, and N155 decreased stability, with deamidation at
N120 and at N155 decreasing stability the most. βA3 formed a hetero-oligomer with
βB1 at a one-to-one ratio. The deamidated mutants, Q42E, N120D, and N133D formed
similar size hetero-oligomers. However, N54D and N155D formed hetero-oligomers
with a lower molecular weight, suggesting disruption of the oligomer formation.
Conclusions: These results suggest that the effect of deamidation on the structure,
stability, and interactions with β-subunit, βB1, are dependent on the specific location of
the deamidation. These in vitro experiments strongly suggest that specific deamidations
on the surface of βA3 alter subunit interactions and higher oligomer state, and may
be contribute to the insolubilization reported in aged and cataractous lenses in vivo.
CR: T. Takata, None; K. Lampi, None.
Support: NIH-EY012339
3801
415. Color Vision and Photoreceptors Organizing Section: VI
3826 - A369
Colour Vision Deficiency in Stargardt Disease
B.P. Leroy1A, C.M. Breusegem1B, P. Kestelyn1B, J.-J. De Laey1B, S. De Bie1C, E. De Baere1C,
A. Uvijls1B. ADept Ophthalmology & Ctr Med Genetics, BDept Ophthalmology, CCtr
Med Genetics, 1Ghent University Hospital, Ghent, Belgium.
Purpose: To investigate whether colour vision deficiency (CVD) in patients with Stargardt
disease (STD) is predominantly in the red-green axis (R/G) as is often described. If present,
whether the R/G defect is a pseudoprotanomaly. And, to establish whether a correlation
exists between best-corrected visual acuity (BCVA) loss and degree of CVD.
Methods: A retrospective, cross-sectional study of 31 patients (62 eyes) with STD who
underwent CV testing using Ishihara, Tritan Plate & Hardy-Rand-Rittler (HRR) pseudoisochromatic (PIC) plates and the Panel D-15 test (PD-15) under standardised C-light. In
addition, 9 patients underwent Nagel anomaloscopy. All patients had a clinical diagnosis
of STD, confirmed by identification of mutations in ABCA4.
Eyes were allocated to 5 groups based on BCVA.
Results: CV was normal in 9/62 eyes (15%).
All tests showed a progressive increase of the number of R/G CVDs as BCVA declined.
In 53 eyes with BCVA below 0.75, R/G CVD of the deutan type were established in about
50% with Ishihara plates.
The Tritan plate showed R/G CVD in all BCVA groups.
Results of the HRR test showed a R/G CVD in at least 50% of eyes for all BCVA categories.
Where specificity of the R/G CVD could be established, a more equal distribution between
deutan and protan subtypes was noted.
With the PD-15 test, a progressive increase of the number of R/G CVDs of the protan
type became apparent as BCVA decreased further below 0.5. In contrast, the ratio of R/G
CVDs of the deutan type remained fairly constant.
Both HRR and PD-15 tests showed additional Blue/Yellow (B/Y) CVDs predominantly
in groups with lower BCVA. In eyes with BCVA <0.1 these additional B/Y CVDs tended
towards scotopisation on PD-15.
Overall, PIC plates & PD-15 tests showed aspecific R/G CVDs in 53 eyes.
However, anomaloscopy performed in 9 patients, revealed a pseudoprotanomaly in 8
and a pseudodeuteranomaly in 1.
Conclusions: CV can be normal in eyes with STD and good BCVA.
In those STD eyes with BCVA below 0.75, CVDs were initially and predominantly of
the R/G type, with additional B/Y defects manifesting as BCVA declined, eventually
leading to scotopisation.
Surprisingly, in eyes with BCVA below 0.50, the Ishihara test showed a deutan type
R/G CVD in 50%.
A predominance of pseudoprotanomaly was evident only on anomaloscopy.
CR: B.P. Leroy, None; C.M. Breusegem, None; P. Kestelyn, None; J. De Laey, None; S.
De Bie, None; E. De Baere, None; A. Uvijls, None.
Support: FWO Grants 1.2.843.07.N.01 & 1.5.244.05 & 3G004306 & OZP Grant 3G004306
3828 - A371
Evidence of NHP Spectral Sensitivity Deficits Associated With Retinal Nerve
Fiber Layer (RNFL) Damage Derived From a Pursuit Motor Tracking Task at
Suprathreshold Exposure Levels Temporal to the Macula
3827 - A370
Visual Function in Parallel Retinocortical Pathways in Affected Individuals
From 8 Families With Autosomal Dominant Optic Atrophy
A.A. Reis1,2, T. Viegas1, C. Mateus1, E.D. Silva1,2, M. Castelo-Branco1. 1IBILI, Faculty
of Medicine, Coimbra, Portugal; 2Ophthalmology, University Hospital, Coimbra,
Portugal.
Purpose: To characterize different phenotypes of Kjer optic atrophy along different
visual pathways and to correlate them with structural features.
Methods: Novel computerized psychophysical assessment methods (CCT - Cambridge
Colour Test and CSF - Metropsis Contrast Sensitivity Function Test) were used to
evaluate visual function in a population of 13 subjects (26 eyes) from 8 families with
Autosomal Dominant Optic Atrophy (ADOA). This evaluation was completed with
electrophysiological assessment (Pattern ERG, Pattern and Multifocal VEP) and
Automated Static Perimetry (ASP). Statistical analysis was performed using ANOVA
at a significance level of p< 0.05.
Results: CCT shows evidence for severe damage of all cone populations, and of similar
magnitude, implying concomitant damage of parvo and koniocellular pathways.
Achromatic contrast sensitivity was severely impaired for all six spatial frequency
channels studied. A decrease on PERG amplitude was found and is consistent with
the observed Pattern VEP/mfVEP and ASP impairments.
Conclusions: Our results suggest that all types of fibers are damaged in ADOA.
Multimodal psychophysical and electrophysiological methods are good quantitative
markers to understand the pathophysiology of damage of central and peripheral
pathways in this condition.
CR: A.A. Reis, None; T. Viegas, None; C. Mateus, None; E.D. Silva, None; M.
Castelo-Branco, None.
Support: None
3829 - A372
Color Constancy as Demonstrated by Low Vision Patients and a Subject With a
C203R Gene Mutation
H. Zwick1, P. Edsall2, D.J. Lund 3, R. Cunningham4, B.E. Stuck 5. 1Research Psychologist,
USAMRD - WRAIR, Castro Valley, CA; 2Research Physicist, Northrup Gromman
Corp, San Antonio, TX; 3Research Physicist, USAMRD - WRAIR, USArmy Medical
Research Detachment, San Antonio, TX; 4Research Biomedical Technician,
USAMRD - WRAIR, San Antonio, TX; 5Research Psychologist, USAMRD - WRAIR,
US Army Medical Research Detachment, TX.
Purpose: Intact retinal visual function provides the visual guidance component for the
highly integrated visual motor interaction required for a visual motor performance task
(VPMT). In complex visual motor tasks, capability to differentiate retinal dysfunction
from neural motor performance components provides visual function metric for direct
assessment of retinal photoreceptor dysfunction. A metric for separating the sensory
component from the motor component was employed to assess retinal function in
visual pursuit motor performance.
Methods: A spectral sensitivity metric was derived from the visual pursuit motor
task (VPMT) to separate laser induced retinal dysfunction. Laser induced retinal
function was separated from the VPMT by deriving spectral sensitivity functions from
the NHP (non-human primate) VPMT using an up and down threshold technique
ranging from 50 to 70 percent time on target criteria. Spectral sensitivity functions
were plotted for an equal energy spectrum normalized at 580 nm.
Results: VPMT derived spectral sensitivity measurements for both CW (543 nm,
250 msec) and Q-switched (532 nm, 7 nsec) at and above threshold damage levels
required at least 8 weeks of post exposure recovery. Laser induced retinal damage
to the Papillary Macular Bundle (PMB) required about a week prior to visible retinal
evidence of retinal nerve fiber layer loss, indicated functionally by neurally opponent
variations in spectral sensitivity measurements of cone photoreceptor systems.
Conclusions:
A greater loss in visual function was obtained with the spectral sensitivity metric
in revealing longer periods of retinal photoreceptor damage recovery as well as a
5 day delay of inner retinal damage damage to occur in the ganglion cell layer and
associated disruption of complex neurally opponent systems resident in this region
of the retina..
CR: H. Zwick, None; P. Edsall, None; D.J. Lund, None; R. Cunningham, None; B.E.
Stuck, None.
Support: None
J.B. Nolan. Envision, Wichita, KS.
Purpose: In order to determine the type and numbers of the X-linked pigment genes,
a molecular genetic analysis was performed on a subject who exemplified remarkable
color constancy ability despite a profound reduction in visual acuity and a lack of
effective color vision. For the purpose of exploring how the phenomenological color
world of a color vision altered subject who possesses a C203R genetic mutation
compares to the color experience of additional clinically diagnosed vision-altered
patients exemplifying various forms of color alterations and also in comparison to
color normal controls, and to assess whether the sensitivity of receptors will influence
one’s description of color, a color naming procedure was utilized.
Methods: Our subject (TJ) is a 32 year old male who exemplified 20/160 acuities in both
eyes and has been diagnosed with congenital cone dysfunction syndrome.. This subject
failed all plates in the Ishihara color plate test. Molecular genetic analysis (courtesy of M.
Neitz and J. Neitz, Medical College of Wisconsin) was performed on TJ to determine
the type and numbers of the X-linked pigment genes. Additional subjects (n=10) had
previously been diagnosed with numerous vision conditions resulting in altered
forms of color vision. They exemplified best-corrected visual acuities ranging from
20/100 to 20/600 in both eyes. Color vision deficiencies were detected with Ishihara
Color Plates). All Subjects and 10 color normal controls were tested using a standard
pallet of nominal color regions.
Results: DNA sequencing revealed that subject TJ does not possess a gene that encodes
for L photopigment (suggesting that TJ is an obligate protanope). DNA sequencing has
also revealed the C203R mutation in a subset of the M genes for TJ. Subject. Data for
color naming showed that although the regions chosen by TJ and our other coloraltered experimental subjects for the 11 basic color terms were quite large and slightly
shifted, they were in rough agreement with control subjects indicating a form of color
constancy in this reduced visual acuity, color-altered population.
Conclusions: Despite the fact that TJ exemplifies a C203 mutation of his M pigment
genes and other subjects show reduced visual acuity and altered forms of color vision
they show consistency in naming colors as well as characteristic shifts and confusions. Thus,
results for subject TJ suggest: A very small photoreceptor complement may be sufficient
for natural color discrimination and categorization. As such, the present results call
into question models of color vision deficiency based on a simple reduction of the
available receptoral mechanisms.
CR: J.B. Nolan, Envision, F.
Support: None
3826-3829
3830 - A373
In vivo Imaging of the Photoreceptor Mosaic in a Congenital Rod Monochromat
3831 - A374
Local and Global Anisotropies in Cone Photoreceptor Packing
J. Carroll1, S.S. Choi2, D.R. Williams3. 1Ophthalmology, Medical College of Wisconsin,
Milwaukee, WI; 2University of California-Davis, Davis, CA; 3Center for Visual
Science, University of Rochester, Rochester, NY.
T. Chui, H. Song, A. Bradley, S.A. Burns. School of Optometry, Indiana University,
Bloomington, IN.
Purpose: Complete achromatopsia (i.e., rod monochromacy) is a congenital vision
disorder in which cone function is absent or severely diminished, due to mutations in
one of 2 components of the cone phototransduction cascade (transducin or the cyclicnucleotide gated channel). Previous histological data concerning cone structure are
conflicting; suggesting anywhere from normal numbers of foveal cones to a complete
absence of foveal cones. Here we sought to determine the photoreceptor complement
in a genotyped achromat.
Methods: A male (ACH0016) diagnosed with complete achromatopsia (age 28) and
his mother (ACH0015), a carrier (age 50), were recruited for this study. Complete
ophthalmologic examinations were done on both subjects just prior to retinal imaging,
which was performed over a 2-day period. Images of the photoreceptor mosaic were
obtained using an adaptive optics ophthalmoscope. Color vision was assessed using
a variety of tests, including the Rayleigh match, pseudoisochromatic plates (AO-HRR,
Dvorine and Ishihara) and the Neitz Test of Color Vision. DNA analysis was done
previously, revealing that ACH0016 was homozygous for a common CNGB3 mutation
(Thr383fs) and ACH0015 was heterozygous.
Results: Behavioral and electrophysiological data from the patient (AOCH0016) were
consistent with an absence of cone function. Images for ACH0016 were obtained at
1.25, 2.5, 4, and 10 degrees temporal from fixation (OD). Numerous photoreceptors
are visible in all 4 images, though the photoreceptor mosaic is severely disrupted
compared to images from a normal retina. The density of the photoreceptors was
consistent with normal rod, not cone, densities. Images from the heterozygous carrier
mother (at 1.25 and 2.5 degrees, OD) revealed no obvious disruption. An analysis of
her retinal images revealed a continuous mosaic in which the photoreceptors were
of a density characteristic of cones.
Conclusions: Here we presented the first in vivo images of the photoreceptor mosaic
of a rod monochromat and found no evidence for structurally intact cones. The genetic
and phenotypic diversity of the disease forecasts considerable variability in the
relative number of residual cones in other achromats. Thus, examination of additional
genetically classified patients with high-resolution retinal imaging is likely to provide
valuable insight into pathogenesis of the disease as well as identify those individuals
who might be most receptive to newly developed gene therapies.
CR: J. Carroll, None; S.S. Choi, None; D.R. Williams, Optos, C; Optos, P.
Support: Research to Prevent Blindness, NIH Grants EY14749, EY01319, & EY04367,
and the NSF Science and Technology Center for Adaptive Optics
Purpose: To use high resolution retinal imaging to investigate local and global
anisotropies in cone densities within the central retina of emmetropic adults.
Methods: A high resolution adaptive optics scanning laser ophthalmoscope (AOSLO)
(bandwidth = 50nm) was used to image the cone photoreceptors of human eyes.
Photoreceptor mosaics covering the entire central 9 mm2 of retina were obtained by
using programmable displacements of scanning mirrors and careful fixation. Cone
counts in a series of 100 x100 micron retinal areas sampled every 250 microns across
the central retina were obtained using a custom Matlab program (MathWorks, Natick,
MA). Local anisotropy (meridional variation in sampling within a local region) and
global anisotropy (sampling differences across retinal meridians) in spacing of cone
photoreceptor were studied by analyzing the Fourier power spectra at different retinal
eccentricities along 90 degree, 135 degree, and 180 degree meridians.
Results: Cone density was within the bandwidth of the imaging system for all the
peri- and parafoveal regions, but cone counting was not possible in the central 0.5
degrees. Cone photoreceptor spacing was 8-15% larger in the radial direction than
in the tangential direction at all eccentricities. Iso-eccentric samples obtained along
the primary retinal meridians (90, 135 and 180) revealed a minor global anisotropy
that was stable across eccentricity and revealed highest sampling density along the
horizontal meridian.
Conclusions: Throughout the perifoveal and parafoveal retinal regions, our in vivo
imaging reveals both local and global anisotropies similar to those reported for a
single cadaver eye (Curcio and Sloan, 1992). These data support the psychophysical
observations of higher VA along the horizontal meridian but are inconsistent with
the standard oblique effect observed psychophysically within the central 18 degrees
(Berkley et al., 1975; Rovamo et al., 1982).
CR: T. Chui, None; H. Song, None; A. Bradley, None; S.A. Burns, None.
Support: NIH grants R01 EY14375 and R01 EY04395
3832 - A375
Arrangement of the Human Trichromatic Cone Mosaic in Peripheral Retina
3833 - A376
Does Foveal-Like Peripheral Color Appearance Exist?
O. Masuda1, H. Hofer2, J. Carroll3, D.R. Williams1. 1Ctr for Vis Science, University
of Rochester, Rochester, NY; 2College of Optometry, University of Houston,
Houston, TX; 3Department of Ophthalmology, The Medical College of Wisconsin,
Milwaukee, WI.
L.S. Baker, A.R. Trujillo, V.J. Volbrecht, J.L. Nerger. Psychology, Colorado State
University, Fort Collins, CO.
Purpose: Previous studies have concluded that the packing arrangement of L and M
cones near the center of the human fovea is not distinguishable from random in most
eyes. We sought to determine whether this is also true for extrafoveal retina.
Methods: We classified the L, M, and S cones in one female color-normal subject with
adaptive optics imaging combined with retinal densitometry at 1.25 , 4, and 10 deg
in the temporal retina. We evaluated the packing arrangement of the 3 cone classes
by comparing the frequencies of distances between all cones of the same type with
those expected based on a random pigment assignment rule.
Results: 314 cones were classified at 10 deg, 739 at 4 deg, and 1456 at 1.25 deg. The
number of misidentified L and M cones at each location was estimated at 3.9 %, 2.8 %,
and 2.5 % respectively. Though the ratio of L to M cones did not differ significantly
across the eccentricities tested, peripheral L and M cones exhibited significant
clumping whereas those at 1.25 deg did not.
Conclusions: The organization of L and M cones outside the fovea, at least in one
subject, shows a clear tendency toward clumping of cones of like type. This clumping
may have implications for the strength of red-green color vision in peripheral retina
since it increases the probability that peripheral midget cell centers will be driven
by predominantly one class of cone.
CR: O. Masuda, None; H. Hofer, None; J. Carroll, None; D.R. Williams, Optos,
Inc., C; adaptive optics, P.
Support: NIH EY04367, NIH EY01319 and the NSF Science and Technology Center for
Adaptive Optics (cooperative agreement no.: AST-9876783 with UCSC)
Purpose: It has long been known that as stimulus size is increased in the peripheral
retina, color appearance becomes more foveal-like, i.e., the stimulus becomes more
saturated and the four elemental hues (blue, green, yellow, red) are more easily
discerned. What has not been established is whether the relationship among the four
hues is maintained between the fovea and peripheral retina. This study examines the
hue relationships in color appearance between the fovea and peripheral retina.
Methods: Color-naming data were determined in the fovea and at 10 deg temporal
retinal eccentricity using monochromatic stimuli (440-660 nm) presented at four
retinal illuminance levels (0.3 to 3.3 log tds). In the peripheral retina, stimuli were
presented at various stimulus sizes (.098 deg to 5 deg) under conditions to either
maximize (no bleach) or minimize (bleach) rod input; only a 1 deg stimulus was used
for the foveal measurements.
Results: Color-naming data obtained in the peripheral retina with the largest stimulus
were compared to the 1 deg foveal data at each retinal illuminance level. In each case
the stimulus size filled the perceptive field for each elemental hue. In general, there
were no differences between the peripheral and foveal saturation functions within
the bleach and no bleach conditions; however, hue functions did differ, especially
under no bleach conditions. In the no bleach condition, the green and yellow colornaming functions extend to shorter wavelengths compared to the fovea and this
difference is greatest at the lower intensities. The same pattern was observed for
short-wavelength redness, but long-wavelength redness is reduced in the peripheral
retina at the higher intensities.
Conclusions: While saturation may be comparable between foveal and peripheral
conditions when stimulus size is appropriately adjusted to fill perceptive fields, the
hue perceptions differ. Hue differences between the fovea and peripheral retina
are greatest in the no-bleach condition, but are still present in the bleach condition.
Assuming rod signals were effectively eliminated in the bleach condition, this result
suggests differences in foveal versus peripheral cone functioning.
CR: L.S. Baker, None; A.R. Trujillo, None; V.J. Volbrecht, None; J.L. Nerger,
None.
Support: None
3830-3833
3834 - A377
Development and Application of a Model Based Transformation for Technical
and Physiological Colour Spaces
3835 - A378
Color Adaptation: Surround Influence on Macadam Ellipses Measured With the
Mollon-Reffin Test
S. Klee, P. Bessler, J. Haueisen. Institute of Biomedical Engineering and Informatics,
Technical University of Ilmenau, Ilmenau, Germany.
A.R. Rodrigues, B.D. Gomes, G.S. Souza, I.B. Taccolini, C.A. Saito, L.C.L. Silveira.
Departamento de Fisiologia, Universidade Federal do Pará, Belém, Brazil.
Purpose: The cone types of the eye differ in calcium metabolism, membrane
permeability, amount and distribution. That implies different vulnerabilities to specific
eye diseases e.g. retinitis pigmentosa or glaucoma. To achieve a diagnostic benefit
based on these properties the excitation of several cone types is needed. Therefore a
free adjustable RGB-colour stimulator is required. Our aim was to develop a model
of the biological effect as a basis for the right choice of a suitable stimulator.
Methods: The spectral distribution function of the irradiance provided the basis for
the model. The measured spectra of each colour and each stimulator were transformed
in CIE 10° colour system using the CIE colour matching functions. In result every
colour was described by a set of three virtual colour values (XYZ). In this system an
adjustment to standard illuminants and other calibrations can be done very easily. For
calculation of the biological effect as the amount of radiation per unit area of the retina
(LMS values), we used another transformation based on spectral sensitivity functions
from Hunt. Because the controlling of the stimulators was performed with a PC graphic
card, we finally transformed the PC colour space (RGB) into the XYZ system.
Results: Through the combination of all transformation steps we were able to compute
the biological effect produced by various stimulators and their colours. We applied the
model on different stimulator technologies and types e.g. LCD, LCoS, DMD, plasma
and a novel LCD combined with LED illumination. Using the example of an S-cone
stimulus (R,G,B = 0,0,255) we computed differences in the values for the biological
activation level of more than 25%. By consideration of all calculated LMS values, we
could find an ideal colour stimulator.
Conclusions: The presented model allows to calculate the biological effect (LMS
values) caused by any colour stimulus from the RGB space. This provides a basis for
choosing a suitable colour stimulator needed for an efficient selective cone excitation.
The example of an S-cone stimulus showed great differences in the biological activation
level witch are closely linked to the stimulator technology. The novel LED-LCD
technology looks very promising with excellent LMS values.
CR: S. Klee, None; P. Bessler, None; J. Haueisen, None.
Support: BMBF: FKZ 13N8521, FKZ 03IP605
Purpose: Adaptation to surrounds varying in luminance has an effect on both color
appearance and discrimination along different directions of the color space. We
determined MacAdam color discrimination ellipses at 2 different surround conditions,
using the Mollon-Reffin (1989) protocol in a psychophysical computer controlled
system for IBM RISC/6000 workstations.
Methods: 31 normal trichromats (22.4 ± 2.1 years old) were monocularly evaluated. The
target was a Landolt C located in a surround of different chromaticity. Two reference
chromaticities were used for the surround, C2 (CIE 1976: u’= 0.219; v’= 0.480) and C3
(CIE 1976: u’= 0.225; v’= 0.415). Discrimination thresholds were evaluated along 20
chromaticity axes irradiating from the reference points and the results were plotted
as MacAdam ellipses. The subject was asked to indicate the C’s opening orientation
as the chromatic contrast between target and reference chromaticities was varied
until the discrimination threshold had been determined, using a staircase procedure.
Thresholds were evaluated using two conditions: (i) the mosaic embedded on a black
background; (ii) the mosaic embedded on a background with chromaticity equal to
that of the reference point and luminance equal to the mosaic mean luminance.
Results: The discrimination thresholds were plotted in the cone excitation space, fitted
as MacAdams ellipses, and cone contrast values obtained with the two conditions
were compared. For both conditions C3 ellipses had larger diameter (circle of equal
area), larger angle of inclination, and larger ellipticity (semi-axis a / semi-axis b)
than C2 ellipses. Both C2 and C3 ellipses were smaller, and C2 ellipses had smaller
ellipticity when the mosaic was presented in the condition (ii) (one-way ANOVA; p
< 0.05). Subjects’ improvement in chromatic discrimination when using condition
(ii) occurred in all color directions except near the tritan confusion line for C2 and
C3 ellipses, near the protan confusion line for the C2 ellipse, and near the deutan
confusion line for the C3 ellipse.
Conclusion: The results indicate that presenting the mosaic in a background with
equal mean luminance and chromaticity equal to the chromaticity of the reference
point increases the subject performance along directions of the color space away from
the protan, deutan, and tritan directions. This suggests a possible effect of luminance
and chromatic adaptation in color discrimination thresholds.
CR: A.R. Rodrigues, None; B.D. Gomes, None; G.S. Souza, None; I.B. Taccolini,
None; C.A. Saito, None; L.C.L. Silveira, None.
Support: CNPq, CAPES, FUNTEC, and FINEP IBN-Net
3836 - A379
First Appearance of Spectral Luminance and Color-Opponent Responses and
Their Interaction in the Afferent Visual System
3837 - A380
Normal Dark Adaptation Results for the Roland Consult Dark Adaptometer
H.G. Sperling. Ophthalmology, Univ of Texas Med School at Houston, Houston, TX.
Purpose: To determine where in the afferent neural chain of the visual system the
combination of photoreceptor responses which match psychophysical luminance and
psychophysical color functions first occur.
Methods: Spectral sensitivity functions were determined for a-wave, b-wave and
pattern ERG stimulation and compared with the increment-threshold spectral
sensitivity and luminance functions of human and rhesus.
Results: The bipolar level spectral sensitivity from b-wave ERG response closely
resembles the psychophysical luminance function. The pattern ERG spectral sensitivity
closely resembles the psychophysical increment-threshold sensitivity. The two differ
with the first appearance of greatly amplified short wave response and red-green
inhibition at the ganglion cell level in the pattern ERG. When 10deg. homogenous
fields are substituted for 1cpd alternating checks in the pattern ERG determinations,
the function regresses to resemble the bipolar cell luminance-like function. These data
will be discussed in relation to the Helmholtz-Kohlrausch Effect.
Conclusions: Color-opponency and short wave amplification are available in
the ganglion cell level response in the retina, as is luminance information in the
bipolar level response. Eliciting the one or the other is controlled by spatial stimulus
factors.
CR: H.G. Sperling, None.
Support: NIH grant EY14906
J.A. Roussey, F. Zwas, I. Glybina. Opthalmology, Kresge Eye Institute, Detroit, MI.
Purpose: To develop a normative database for dark adaptation for the Roland Consult
Dark Adaptometer.
Methods: Two sets of dark adaptation tests were performed in 12 healthy individuals
of 20-30 years of age. Each test was performed upon one eye at a time with intense
white light bleaching for 6 minute prior to the test at 7000 candles/m 2. First test
represented red flash stimulus (all stimuli were at 2° of visual angle) every second for
10 minute, aligned with the center of the eye, focused directly on the light stimulus.
Second test consisted of green flash stimulus every second for 30 minute, with the
eye focused 20° temporal to the light positioned directly in front of the eye. Dark
adaptation functions were analyzed by plotting time on the x-axis against the log
of light intensity on the y-axis. 10 minute and 30 minute were chosen as test times.
Three data sets were obtained and analyzed: red stimulus for the cone receptors and
green stimulus for cone and rod receptors.
Results: The red stimulus test yielded data which was fitted with exponential decay
curves for cone function, with horizontal asymptote at mean value (±StD) of -2.06
± 0.234 log cd/m 2. Mean t-time constant of this curve was 35.0 ± 23.1 s. The green
stimulus test yielded two exponential decay curves, one occurring during the first 10
minutes and the other in the 10 to 30 minute range, demonstrating the adaptation of
cone and rod receptors, respectively. For the cone portion of the test, the horizontal
asymptote had mean value of -1.22 ± 0.357 log cd/m 2 and average t-time constant of
15.3 ± 12.3 s. The rod portion had a mean horizontal asymptote of -3.31 ± 0.458 log cd/
m 2 with mean time constant of 327 ± 110 s.
Conclusions: Our data are being used to establish a normative database for dark
adaptation. This database will be used to assess patients with impaired night vision.
The study is ongoing and more data will be collected, and the database will be
expanded to include patients from other age groups as well.
CR: J.A. Roussey, None; F. Zwas, None; I. Glybina, None.
Support: This research is supported by the May Mitchell Royal Foundation
3834-3837
3838 - A381
Retina Function and Spatial Vision in a Diurnal Cone-Rich Laboratory Rodent,
the Nile Grass Rat (Arvicanthis Niloticus)
S. Bonfield1A, N. Crowder2A, G. Gilmour2A, S. Mema2A, F. Gaillard 3, W.K. Stell1B, Y.
Sauvé2B. ACell Biology and Anatomy, BOphthalmology, Cell Biology and Anatomy,
1
University of Calgary, Calgary, AB, Canada; APhysiology, BOphthalmology,
Physiology, 2University of Alberta, Edmonton, AB, Canada; 3IPBC, University of
Poitiers, Poitiers, France.
Purpose: Research in retinal disorders has come to rely on cone-poor rodent models
such as mice or rats, ~3% of whose photoreceptors are cones. These species are
primarily nocturnal or crepuscular. Here we report on visual function in Arvicanthis
niloticus (Nile grass rat), a diurnal laboratory rodent with 40% cones.
Methods: Optokinetic responses (OKR) to moving gratings were tested using
OptoMotryTM (Cerebral Mechanics, Lethbridge, AB, Canada). Nile grass rats, aged
101-104 days (n = 4), were presented with horizontally drifting sine-wave gratings of
various spatial frequencies (SF = 0.025 c/d - 1.4 c/d) and drift speeds (6, 12, 24 d/s),
rotating to either left or right. Full-field flash cone-driven electroretinogram (ERG)
was also recorded.
Results: OKR: The contrast sensitivity (CS) function appeared nearly flat from SF =
0.025 - 0.8 c/d, with a decline towards higher SFs. CS functions at velocities (V) = 6
and 12 d/s were indistinguishable, whereas CS remained elevated at lower SFs at V
= 24 d/s. The maximal CS was very high (36.5±17.6 at 0.2 c/d, 52.7 ± 37.0 at 0.4 c/d, V =
6 d/s; 42.2 ± 16.3 at 0.2 c/d and 52.9±32.7 at 0.4 c/d, V = 12 c/d), and CS was still rather
high at 0.025 c/d (9.3±1.5 at 6 d/s; 10.1±2.5 at 12 d/s). The highest SF to which all animals
responded at 100% contrast (=“acuity”) was 1.0 c/d. ERG: Several cone ERG features,
absent in laboratory rats and mice, were typical in the Nile grass rat: a) large a-waves
(81±16 µV, n =16); b) a photopic Hill effect; and c) maximal flicker amplitudes maintained
from 5 to 35 Hz without fusing, even at the highest frequency tested, 60 Hz.
Conclusions: The photopic visual responses of the Nile grass rat are robust, in
keeping with its having a cone-rich retina. The OKR contrast sensitivity and acuity
are more than twice as high as in laboratory rats and mice, and several photopic
ERG features are unique to Nile rats. The Nile grass rat is a distinctive species that
shows promise as a model for understanding retinal disorders, particularly those
due to cone pathologies.
CR: S. Bonfield, None; N. Crowder, None; G. Gilmour, None; S. Mema, None; F.
Gaillard, None; W.K. Stell, None; Y. Sauvé, None.
Support: CIHR, Lions’ Sight Fund
3839 - A382
Behavioral Test for Visual Assessment of Canine Achromatopsia
M.M. Garcia1, C. Cocores1, G.-S. Ying2A, J.C. Tanaka1, A.M. Komaromy2B. 1Biology,
Temple University, Philadelphia, PA; AOphthalmology, BClinical Studies,
2
University of Pennsylvania, Philadelphia, PA.
Purpose: Development of a behavioral test using an obstacle course for evaluation
of achromatopsia-affected dogs.
Methods: A 12 x 4 ft obstacle course was constructed with 47.5” tall, white PVC panels.
Panels were set in moveable tracks spaced at varying intervals along the course. Dogs
age 11 weeks to 1.5 years, were tested at four ambient light intensities (0.02, 2.3, 6 and
60 ft-c), 3 trials per dog. New combinations of panel positions were selected for each
trial; 5 normal (carrier) and 5 achromatopsia-affected dogs (CNGB3 mutants) were
evaluated. Visual status was masked to the test operators. All trials were recorded
on DVD and times measured off-line. Time required to complete the course was
compared between groups with univariate and multivariate analyses. In addition,
preliminary trials were conducted with 2 achromatopsia dogs following recombinant
adeno-associated virus-mediated gene replacement therapy.
Results: Once dogs were socialized, they were readily tested without previous course
training. The mean (SE) time to complete the course at 0.02 ft-c was 4.4s (0.29) for
carrier and 4.2s (0.26) for affected dogs (p=0.78). At 60 ft-c, the carrier dogs mean
(SE) time was 4.5s (0.27) and the affected dogs was 25.5s (3.64). Significant time
increases were measured at all light intensities greater than 2.3ft-c (p<0.0003) but no
significant differences in performance were measured at 0.02ft-c (p=0.78) between
groups. These statistical significance differences are maintained after adjustment by
age, gender and trial. Preliminary results in the treated dogs confirmed successful
outcome of gene therapy.
Conclusions: Our obstacle course provides an objective behavioral test for evaluating
dogs with visual impairments such as achromatopsia at different ambient light
intensities. It holds promise as an additional tool for evaluating the outcomes of
new therapies.
CR: M.M. Garcia, None; C. Cocores, None; G. Ying, None; J.C. Tanaka, None; A.M.
Komaromy, None.
Support: EY006855, EY017549, K12 EY015398, P30 EY001583 and FFB
3838-3839
Wednesday, April 30, 11:15 AM - 1:00 PM Room 315 Paper Session Program Number Range: 4023-4029
425. Accommodation and Lens Organizing Section: VI
4023 - 11:15AM
Effect of Lens Capsule Mechanical Properties on the Dioptric Response of
Primate Lenses as Assessed in an ex vivo Accommodation Simulator
4024 - 11:30AM
Cues for the Control of Accommodation & Vergence During Postnatal Human
Development
J.-M.A. Parel1,2, N.M. Ziebarth1,3, D. Borja1,3, E. Arrieta-Quintero1, D. Nankivil1,3, I.
Dortonne1, R. Jain4, A. Ho5,2, F. Manns1,3. 1Ophthalmology, Bascom Palmer Eye Ins/U
of Miami, Miami, FL; 2Vision Cooperative Research Centre, Sydney, Australia;
3
Dept. of Biomedical Engineering, Univ of Miami College of Engineering, Coral
Gables, FL; 4Advanced Medical Optics, Santa Ana, CA; 5Institute for Eye Research,
Sydney, Australia.
S.R. Bharadwaj, T. Candy. School of Optometry, Indiana University Bloomington,
Bloomington, IN.
Purpose: To examine the relationship between the accommodative response of the
natural lens and the force required to stretch the empty lens capsule during simulated
accommodation
Methods: Post-mortem human (n=23) and cynomolgus monkey (n=16) tissues including
the lens, capsule, zonules, ciliary body, and sclera were mounted in an optomechanical
lens stretching system. Starting at zero load, the segmented sclera was symmetrically
stretched in a step-wise fashion from 0 to 2mm in 0.25 or 0.5mm steps at a speed of
0.1mm·s-1. The load, lens diameter, and power were measured at each step. The lens
contents were then removed through a mini-capsulorhexis using hydrodissection and
aspiration or phacoemulsification. The stretching cycles were repeated on the empty
capsular bag. The force required to stretch the empty lens capsular bag was compared
to the power change per gram of force applied for the natural lens. The ratio of the force
required to stretch the empty bag versus natural lens was compared to the change in
natural lens power per gram.
Results: The ratio of force required to stretch the empty bag versus natural lens ranged
from 0.13 to 1.15 (human) and 0.69 to 1.14 (monkey). The change in natural lens power per
gram ranged from -1.37D/g to 0.12D/g (human) and -3.16D/g to -1.35D/g (monkey). As the
ratio of force required to stretch the empty bag versus natural lens increases, the change
in natural lens power per gram also increases. When the lens capsule governs the force
of accommodation (ratio=1.0), the change in power per gram is maximum.
Conclusions: This study suggests that there is a direct relation between lens mechanical
resistance and accommodative amplitude.
Support: NEI grant 2R01EY14225; NSF Graduate Student Fellowship (Ziebarth); NIH
5F31EY15395 (Borja); Australian Government CRC Scheme through the Vision Cooperative
Research Centre, Sydney, Australia; Florida Lions Eye Bank; AMO Inc, Santa Ana, CA;
NIH center grant P30-EY014801; Research to Prevent Blindness; Henri and Flore Lesieur
Foundation (JMP).
CR: J.A. Parel, F, F; N.M. Ziebarth, None; D. Borja, None; E. Arrieta-Quintero, None; D.
Nankivil, None; I. Dortonne, None; R. Jain, AMO, E; A. Ho, None; F. Manns, None.
Support: 2R01EY14225; NSF(Ziebarth); NIH 5F31EY15395 (Borja); Vision CRC, Sydney,
Australia; Florida Lions Eye Bank; AMO; NIH P30-EY014801; RPB; Henri and Flore
Lesieur Foundation (JMP)
4025 - 11:45AM
A New Analytic Representation of Human Accommodation and Presbyopia
Purpose: Maintaining single & focused visual experience while an object moves
in depth requires the coordination of vergence & accommodation responses. In
adults, retinal blur and disparity are each capable of driving both accommodation
and vergence responses. However, the relative importance of these cues in driving
accommodation and vergence is largely unknown during development. Here we tested
the importance of disparity by comparing the gain of accommodation & vergence in
its presence (binocular viewing) & absence (monocular viewing).
Methods: Subjects (n = 159; age range: 1.9 months - 46 yrs) viewed a high contrast
cartoon target either binocularly or monocularly (left eye) while the target moved at
0.5 D/s between 80 and 33 cms (stimulus size: 1.75 D or MA). Subjects’ accommodation,
vergence & left and right eye positions were measured using the PowerRefractor (Multi
Channel Systems). Cooperation with the task was ensured by only including responses
where the left eye position & stimulus position were well-correlated (r>0.7).
Results: The gains (response size/stimulus size) of accommodation & vergence were
significantly reduced in monocular conditions compared with binocular conditions
(p<0.001), even though the left eye tracked the target similarly in both conditions
(p=0.2). The gain of monocular accommodation was lowest in infants (0.41) & it
increased at the rate of 0.04yr-1 until an adult-like gain of 0.76 was reached by 10.9yrs.
The gain of monocular vergence was also lowest in infants (0.33) & it increased at the
rate of 0.01yr-1 until an adult-like gain of 0.57 was reached by 17.6yrs. The reduction
in monocular accommodative gain was consistent across three forms of monocular
occlusion (IR filter, opaque patch & +20D lens). The accommodation & vergence
gains were poorly correlated with the subjects’ (n = 34; age range: 6.2 months - 16.4
years) cycloplegia refractive error (binocular accommodation: r = 0.17; monocular
accommodation: r = -0.2; binocular vergence: r = -0.2; monocular vergence: r = -0.1).
Conclusions: Reduced vergence gain in monocular conditions is consistent with
predictions based on neural coupling between accommodation & vergence. However,
the reduced gain of accommodation during infancy & early childhood is a new
observation that suggests the developing visual system is inefficient at generating
accommodative responses in the absence of retinal disparity.
CR: S.R. Bharadwaj, None; T. Candy, None.
Support: NIH Grant EY014460
4026 - 12:00PM
Individual Differences in Accommodation to Wavefront Vergence and
Chromatic Aberration: Color Normal and Deutan Observers
J.F. Koretz1A, G.H. Handelman1B. ABiochemistry Biophysics Prog, BMathematical
Sciences, 1Rensselaer Polytech Institute, Troy, NY.
Purpose: To update the geometric (Koretz-Handelman) model of accommodation
in the human eye by incorporating experimental data on changes in lens shape and
thickness into the inverse biomechanical model. An older initial analytic model (Koretz
and Handelman, 1982, 1983), which included a number of approximations to simplify
this representation, was nevertheless extremely valuable in providing guidelines
for development and testing of ideas about accommodation and presbyopia. This
analytic model is being re-derived to (a) eliminate many of the original simplifications,
which limited the model’s applicability; (b) represent the human focusing process
more accurately; (c) enable extension of the model to include data from older, peripresbyopic eyes; and (d) provide a platform for in silico testing of hypotheses about
the development of presbyopia and strategies for treating age-related accommodative
loss.
Methods: Because the changes in lens shape, thickness, and origentation relative
to the cornea can be described very accurately, our strategy continues to be to work
from a complete description of lens deformation during a small accommodative
change to pattern of forces acting upon the lens that cause this deformation. I.e., the
elements of the strain tensor element are derived, and are then used to enable the
stress tensor elements to be completely defined, thereby allowing the tractions to
be described. We have dropped most of our original simplifying assumptions, but
continue to assume that lens material properties are anisotropic in the radial and
polar directions, in agreement with lens fiber cell organization, and that for a small
accommodative change, the meridional distance (arc length) for a generic point on
or in the lens is unchanged.
Results: Analytic expressions for the elements of the strain tensor have been derived
and, using the relationship between stress and strain tensors for an anisotropic,
rotationally symmetric object, the elements of the stress tensor, and thus the tractions,
are also defined. It was not possible to use a polynomial representation of lens
curvature, because the resultant derived equations are not subject to a closed form
solution and thus must be solved numerically. However, it can be shown that, for the
very broad range of possible lens curvatures, a caternary is an excellent substitute
that enables the completion of the derivation.
Conclusions: The completion of this analytic representation provides a new approach
for exploring issues related to the accommodative process and the development of
presbyopia, and can provide experimentally testable hypotheses.
CR: J.F. Koretz, Frey Research, C; G.H. Handelman, None.
Support: Cundari Memorial Research Fund
Y. Wang1, P.B. Kruger1, J.S. Li1, P.L. Lin1, L.R. Stark 2. 1Vision Sciences, State University
of New York, State College of Optometry, New York, NY; 2Southern California
College of Optometry, Fullerton, CA.
Purpose: Longitudinal chromatic aberration (LCA) provides a cue to accommodation
with small pupils. However, large pupils increase monochromatic aberrations, which
may obscure chromatic blur (McLellan, Marcos, Prieto & Burns, Nature, 417, 174, 2002).
We examined the effect of pupil size and LCA on accommodation in color normal
and deutan observers.
Methods: Participants were nine normal trichromats, three deuteranomalous
trichromats, and two deuteranopic dichromats (anomaloscope and D-15).
Accommodation was recorded by infrared optometer (100 Hz) and pupil by videocamera (30 frames/s) while observers viewed a Maltese cross target in a Badal
stimulus system. There were two illumination conditions: white (3000 K; 20 cd/m 2)
and monochromatic (550 nm with 10 nm bandwidth; 20 cd/m 2) and two artificial
pupil conditions (3 mm and 5.7 mm). The target moved sinusoidally (1-3 D at .2 Hz)
during trials lasting 40 seconds. Six trials were run for each condition randomized in
blocks. Gain and temporal phase-lag were calculated by FFT for each trial. Mean pupil
diameter was calculated for each trial. Separately, static measurements of wavefront
aberration were made with the eye accommodating to targets between zero and 4 D
(COAS, Wavefront Sciences).
Results: Dynamic gain to vergence modulation increased significantly with pupil size
in monochromatic (p=.005) but not white light (p=.12), and significantly with addition
of LCA at both pupil sizes (5.7 mm, p=.004; 3 mm, p=.02). There were no significant
differences in dynamic accommodation between color normal and deutan individuals
for any condition (.68≤p≤.96). Normals and deutan observers showed large individual
differences in dynamic gain to vergence and LCA. Mean responses also varied among
individuals, but deuteranomalous observers appeared to over-accommodate compared
to color normal observers (.06≤p≤.12).
Conclusions: Large individual differences in accommodation to vergence and LCA
are a hallmark of accommodation in normal and deutan observers. LCA continues
to provide a signal at large pupil sizes despite higher levels of monochromatic
aberrations. Monochromatic aberrations may defend against chromatic blur at high
spatial frequencies (McLellan et al., 2002) but accommodation responds best at 3 c/
deg where blur from higher order aberrations is less.
CR: Y. Wang, None; P.B. Kruger, None; J.S. Li, None; P.L. Lin, None; L.R. Stark,
None.
Support: NIH 2R01-EYO5901
4023-4026
Wednesday, April 30, 11:15 AM - 1:00 PM Room 315 Paper Session Program Number Range: 4023-4029
425. Accommodation and Lens Organizing Section: VI
4027 - 12:15PM
Change in Optical Aberrations of an Aging Eye Model With Accommodation
4028 - 12:30PM
Age Related Changes of the Posterior Zonule and the Ciliary Body at Rest and
During Accommodation
R. Navarro1, F. Palos1, L. González2. 1ICMA, Consejo Superior de Investigaciones
Cientificas.-Univ. de Zaragoza, Zaragoza, Spain; 2Instituto Nacional de Técnica
Aeroespacial, Madrid, Spain.
M.A. Croft, J.P. McDonald, P.L. Kaufman. Ophthal & Vis Sciences, Univ of
Wisconsin-Madison, Madison, WI.
Purpose: To develop a realistic optical model of the aging eye able to reproduce
high order aberrations present in the human eye and their changes with age and
accommodation.
Methods: We consider the corneal surface as a general non-revolution ellipsoid (this
includes conicity, toricity, deviations and displacements of its optical axis) plus some
deformation modes represented by the coefficients of a Zernike polynomial expansion
(only three coefficients are different from zero). The parameters are average values
obtained in a previous study. An adaptive model of the GRIN lens, together with
this cornea model permits us to include the changes with age and accommodation.
No further fitting of the parameters of the model is applied to compute low and high
order aberrations, except for the conic constants of the lens surfaces.
Results: The model reproduces the average refractive power, astigmatism and the
overall high order aberrations (HOA) present in human eyes. The wavefront pattern
of this generic eye displays spherical aberration, coma, trefoil, etc. and resembles the
appearance of typical wavefronts measured in human eyes. The model also predicts
the changes observed in power and HOA with accommodation. To reproduce the effect
of aging we needed to assume a change of the conic constants of the lens surfaces
towards more negative values, plus some additional decline in optical quality.
Conclusions: A realistic non-rotationally symmetric generic eye model, which includes
changes with age and accommodation has been proposed, which reproduces the
average power, astigmatism and a realistic wavefront. It can be useful to better
understand the optics of accommodation and presbyopia.
CR: R. Navarro, None; F. Palos, None; L. González, None.
Support: CICYT (Spain) Grant FIS2005-05020-C03-01
Purpose: Our goal was to determine the age-related changes in the function of the
posterior zonule and the anatomical relationship of the posterior zonule to the other
relevant intraocular accommodative structures.
Methods: The eyes of nineteen rhesus monkeys, aged 6-27 yrs, were studied.
Edinger-Westphal- (E-W) stimulated accommodation was measured by coincidence
refractometry. The width of the posterior zonular space and the distance from the
scleral spur to the posterior insertion point of the posterior zonule was measured by
ultrasound biomicroscopy (UBM; 50 MHz, 35 MHz).
Results: In the resting eye, the width of the posterior zonular space increased with age
by 0.012 ± 0.0022 mm/yr (p=0.001, r=0.79, n=19), but the distance between the scleral
spur and the posterior insertion point of the posterior zonule did not significantly
change with age (n=3 young , n=3 older). During accommodation, the distance between
the scleral spur and the posterior insertion point of the posterior zonule diminished
(p<0.05) and did so more markedly in the young eyes (0.90 ± 0.09mm, n=3) than in the
older eyes (0.43 ± 0.16mm, n=3), with no overlap. Further analyses are proceeding.
Conclusions: Age-related changes in ciliary body function may be secondary to
the age-related loss in accommodative forward movement of the posterior zonule’s
posterior insertion site. The age-related increase in posterior zonular space in the
resting eye may be due to the decrease in the diameter of the ciliary body ring, which
suspends the anterior end of the posterior zonule.
CR: M.A. Croft, None; J.P. McDonald, None; P.L. Kaufman, None.
Support: NEI (EY10213), RPB, OPREF
4029 - 12:45PM
A Dynamic Demonstration of the Anatomical Basis for Variable Human Lens
Shape Change to Effect Accommodation Throughout Life
J.R. Kuszak1, M. Mazurkiewicz1, R.K. Zoltoski2. 1Ophthalmology, Rush University
Medical Center, Chicago, IL; 2Basic & Hlth Sci, Illinois College of Optometry,
Chicago, IL.
Purpose: The slit-lamp biomicroscope, a low resolution instrument, shows in situ that
different age-related regions of the human lens (fetal, infantile, juvenile and adult
nuclei as well as age-matched cortical region) undergo variable gross shape changes
to effect accommodation throughout life. The purpose of this study was to create an
animation showing the anatomical basis at the fiber cell level for the above described
slit-lamp observations.
Methods: Chemical fixation was used to ‘stop motion’ in human lenses (n = 40+) in
the accommodated and disaccommodated states at different ages (12 - 80+). Lenses
were then dissected in a manner permitting ex vivo analysis with a scanning electron
microscope, a high resolution instrument, of different aged fiber cells as they had
more or less efficiently accommodated throughout life. From the SEM micrographs
scale CAD drawings were then used to restore the dynamics of accommodation
throughout life in an accelerated time lapse CAD movie.
Results: Throughout gestation fibers are formed that do not develop fiber ends
capable of interfacing at the sutures to effect accommodation. However these fibers
are pliable and therefore throughout infancy as the anterior ends of infantile cortical
fiber cells interface at sutures, the shape of the fetal nucleus is altered. By young
adulthood, alterations in the surface morphology of the fetal and infantile nuclear fibers
(development of furrowed membrane domains necessary for long-term survival of lens
fibers) precludes any significant shape change in these regions to effect accommodation.
For the rest of life, the change in surface curvature of the lens to effect accommodation
is a function of the number of growth shells that consist of cortical fiber cells capable
of interfacing at sutures to enable dynamic focusing balanced against the number of
growth shells that consist of nuclear fiber cells rendered incapable of interfacing at
sutures due to the above described age-related surface modifications of fibers.
Conclusions: Fibers formed before sexual maturation are involved in the
accommodative process by either actively interfacing at lens sutures or passively
being compressed in response to the above action. Fibers past sexual maturation are
rendered incapable of participating in the accommodative process due to the necessity
of developing age-related modifications in their structure to ensure their long-term
survival. The animations highlight how previously unrecognized alterations in fiber
cell morphology can affect accommodation.
CR: J.R. Kuszak, None; M. Mazurkiewicz, None; R.K. Zoltoski, None.
Support: NEI EY00642
4027-4029
Wednesday, April 30, 11:15 AM - 1:00 PM Hall B/C Poster Session Program Number/Board # Range: 4102-4118 / A79-A95
434. Low Vision Organizing Section: VI Contributing Section: RE
4102 - A79
Central Field and PRL Characteristics in Low Vision Patients - A 10 Year
Comparison
4103 - A80
Foveal vs. Eccentric PRL Characteristics for Fixation in Low Vision Patients
D.C. Fletcher1,2, R.A. Schuchard 3. 1Ophthalmology, California Pacific Medical Center,
San Francisco, CA; 2Smith-Kettlewell Eye Research Institute, San Francisco, CA;
3
VA Rehab R&D Center, Atlanta, GA.
T.D. Martin1, M. MacKeben2, R.A. Schuchard 3, D.C. Fletcher1. 1Ophthalmology,
California Pacific Medical Center, San Francisco, CA; 2Low Vision, SmithKettlewell Eye Research Institute, San Francisco, CA; 3VA Rehab R & D Center,
Atlanta, GA.
Purpose: To compare Scanning Laser Ophthalmoscope (SLO) central field and PRL
characteristics in current low vision patients to a study reported in 1997.
Methods: 501 eyes of 273 recent patients referred for low vision rehabilitation
had visual acuity (ETDRS), macular perimetry for dense scotomas (SLO) and PRL
characteristic (SLO) testing performed in their initial evaluation. The size of scotomas,
PRL position relative to scotomas, and relative to the fovea were noted. A scotoma
within 2.5 degrees of the PRL or fovea to either superior, right, left or inferior margins
was considered a bordering scotoma. This constituted a repeat study of 1336 eyes of
825 patients reported in Ophthalmology 1997 to which comparisons are made.
Results: Demographic and diagnostic characteristics were similar, with median
ages close to 80 and more than two thirds having maculopathies in both studies.
34% (1997) and 30% (2007) of patients had < 20/400 visual acuity. 91% (1997) and 88%
(2007) of patients had dense scotomas in the central 20 degrees. 69% (1997) and 66%
(2007) had dense scotomas larger than 5 degrees diameter. PRLs/Foveas with dense
scotoma borders: None - 11% (1997) and 18% (2007); One Border - 41% (1997) and 37%
(2007); Two Borders - 19% (1997) and 22% (2007); Three Borders - 9% (1997) and 8%
(2007); Four Borders/Ring Scotoma - 19% (1997) and 15% (2007). PRLs/Foveas with
dense scotoma field borders: Superior - 46% (1997) and 48% (2007); Right - 49% (1997)
and 49% (2007); Left - 32% (1997) and 40% (2007); Inferior - 29% (1997) and 28% (2007).
With respect to foveal status, in 1997 only 18% of patients had a functioning fovea
where as in 2007 50% had a functioning fovea.
Conclusions: In 2007 the vast majority of low vision patients present with central
visual field disruption, as was the case in 1997. Characteristics in the position of the
scotoma relative to the PRL/Fovea remained remarkably consistent. There is a small
tendency to fewer patients with profoundly impaired visual acuity and fewer with
large scotomas. Currently more patients present for low vision rehab with functioning
foveas than 10 years ago. More functioning foveas has implications for rehabilitation
services and may also reflect positively on new treatments for exudative maculopathies
not available 10 years ago.
CR: D.C. Fletcher, None; R.A. Schuchard, None.
Support: Pacific Vision Foundation
Purpose:To compare Scanning Laser Ophthalmoscope (SLO) foveal fixating
characteristics with eccentric PRL fixating characteristics in low vision patients.
Methods:501 eyes of 273 patients referred for low vision rehabilitation had visual
acuity (ETDRS) and PRL characteristic (SLO) testing performed in their initial
evaluation. The PRL position relative to the fovea and fixation stability/size of the
PRL were measured utilizing a SLO testing program with a gaze-contingent stimulus
display (MacKeben et al, JOSA A 24/5, 2007).
Results:Patient age median/range was 80/6 - 99 years and 59% were female. 77% had
a maculopathy, with several other diagnoses in the remaining 23%. Visual acuity (VA)
median/range was 20/200 and 20/20 - 20/3509. 50% (250/501) of eyes demonstrated
fixation at the fovea. VA for the foveal fixation group median/range was 20/100 and
20/20 to 20/879 and for the eccentric PRL group was 20/401 and 20/46 to 20/3509. The
median (range) of the diameter of the fixation area for the foveally fixating group was
2 (1-6) degrees while the eccentric PRL group median (range) was 5 (2-12) deg. The best
possible fixation stability and VA decreased with distance from the fovea but there
were many values that were worse than this best possible value at all distances from
the fovea. There was a moderate significant relationship between VA and stability/
size of the PRL with a floor effect also (RSquare 0.43).
Conclusions:This study of patients referred for low vision rehabilitation demonstrates
that many have fixation at the fovea. An eccentric location of the PRL is associated
with lower acuity and less stable fixation but VA at the fovea can be in the profound
impairment category and the fixation area can be large and fixation can be unstable.
In rehabilitation of low vision patients, it cannot be assumed that decreased acuity
or unstable fixation indicate an eccentric PRL.
CR: T.D. Martin, None; M. MacKeben, None; R.A. Schuchard, None; D.C. Fletcher,
None.
Support: None
4104 - A81
Microperimetry Study in Low Vision Patients Submitted to IOL VIP Visual
Rehabilitative System
4105 - A82
Driving with Hemianopia: Head Scanning and Detection Performance in a
Simulator
R. Fasciani1A, L. Mosca1A, F. De Rossi1A, L. Guccione1A, G. Maione1A, E. Legrottaglie1A,
N. Nicolotti1B, E. Balestrazzi1A. AEye Clinic, BEpidemiology and Biostatistics Unit,
1
Catholic University of Sacro Cuore, Rome, Italy.
A.R. Bowers, A.J. Mandel, R.B. Goldstein, E. Peli. Schepens Eye Research Institute,
Dept Ophthalmology Harvard Med School, Boston, MA.
Purpose: To evaluate the changes of fixation pattern, retinal sensitivity using
microperimetry in low vision patients affected by macular degeneration submitted
to rehabilitative program by means of IOL VIP System (Intraocular Lens for Visually
Impaired People, Subvision, Milano, Italy).
Methods: 11 eyes of 7 patients (4M, 3F), mean age 70.1yrs ± 12.46SD (range from 55
to 81), affected by macular degeneration, were submitted to IOL VIP implantation (3
in both eyes; 5 in one eye). Mean preoperative best corrected visual acuity (BCVA)
was 0.06 ± 0.08SD. The system consists in both rehabilitative and surgical procedure
studied to improve vision capabilities. The practice with a special computer software,
performed before and after surgery to train the PRL, allows patients to use IOL
VIP implant. The surgical technique consists in a phacoemulsification of cataract
followed by implantation of two IOLs: one in the bag and one in the anterior chamber.
These two IOLs realize a Galilean telescopic system with 1.3 X magnification. Using
microperimetry (MP1, Nidek Technologies, Tokyo, Japan), the position and stability of
PRL and the retinal sensitivity property were studied. The changes of PRL’s stability
and position and improvement of BCVA were analyzed and compared at the time 0
(pre-rehabilitation), at time the 1 (after software PRL training) and at time 2 (3 months
after surgery). Statistical analysis was made using Wilcoxon Signed Ranks Test in
SPSS 12.0 Statistical Program (α < 0.05).
Results: All treated patients reached an improvement in the visual acuity (postsurgery BCVA was 0.145 ± 0.19SD), stability and better positioning of PRL (fixing
closer scotoma’s edge). The best fixation stability, location of PRL and BCVA were
achieved after the complete procedure (p=0.003); instead, the PRL training alone
allowed lower but anyway significant changes (p= 0.041). No significant changes
of the retinal sensitivity and of scotoma dimensions were seen during the entire
rehabilitative program.
Conclusions: IOL VIP System seems to be a safe and effective combined therapeutic
technique for central low vision patients. Microperimetry highlights the effect and
the progress of the rehabilitation procedure.
CR: R. Fasciani, None; L. Mosca, None; F. De Rossi, None; L. Guccione, None; G.
Maione, None; E. Legrottaglie, None; N. Nicolotti, None; E. Balestrazzi, None.
Support: None
Purpose: Drivers with hemianopia may have difficulty detecting objects on the side
of the vision loss, which could adversely affect both the safety of the driver and other
road users. We conducted a simulator-based evaluation to investigate how well drivers
with hemianopia compensated for their vision loss when performing a driving-relevant
detection task. In addition, we evaluated head-scanning behaviors and examined
whether increased head-scanning resulted in better detection at intersections.
Methods: Twelve patients with complete homonymous hemianopia but without
visual neglect (6 left and 6 right) were compared to 12 age and gender case-matched
normally-sighted drivers. Participants drove for about 60 minutes in a high-fidelity
simulator on two occasions, one week apart. The primary task was to detect and
respond (by a horn press) to the appearance of pedestrian targets in a variety of traffic
situations. “Roadway” targets (72 per session) appeared either on the left or right
of the road at small (4°) or large (14°) eccentricities and “intersection” targets (5 per
session) were placed at or near intersections. Head movements were recorded with
an optical tracking system. An algorithm was developed to identify and quantify
head scans (movements away from the straight ahead position).
Results: Roadway target detection rates of hemianopic drivers were lower on the
blind side (median 44%) than the seeing side (97%; p = 0.002), and were lower at the
larger (25%) than the smaller eccentricity on the blind side (65%; p = 0.002). On the
seeing side, detection rates were similar to those of normally-sighted drivers (100%).
Amongst the hemianopic drivers, detection rates varied widely (19 to 93%); lower
roadway detection rates were associated with older age (Spearman rho = -0.67, p =
0.02). Normally-sighted drivers detected 88% of targets on the extreme right and left
of intersections, but drivers with right hemianopia detected only 8% of targets on
the extreme right (p < 0.001) and drivers with left hemianopia detected only 39% on
the extreme left (p < 0.001). Drivers with hemianopia failed to scan to the blind side
at 10% of intersections (range 0 to 30%). Higher detection rates at intersections were
associated with lower failure-to-scan rates and greater numbers of scans to the blind
side (Spearman rho = -0.90 and 0.78, respectively; p < 0.001).
Conclusions: These results provide evidence of widely varying levels of compensation
and detection abilities amongst drivers with hemianopia and suggest that increased
head-scanning results in better detection performance at intersections.
CR: A.R. Bowers, None; A.J. Mandel, None; R.B. Goldstein, None; E. Peli, None.
Support: NIH grants EY12890 and EY14723; Center for Innovative Visual Rehabilitation,
Boston VA Medical Center (J. Rizzo)
4102-4105
4106 - A83
Effect of Hemianopia on Lateral Lane Position in a Driving Simulator
4107 - A84
Validating a New Metric for Assessing the Discriminability of Vehicular Gap
Times Using Different Amounts of Sensory Information
E. Peli, A.R. Bowers, A.J. Mandel, R.B. Goldstein. Schepens Eye Res Inst, Dept
Ophthalmology Harvard Med School, Boston, MA.
Purpose: Hemianopic visual field loss may have adverse effects on vehicle control skills.
We conducted a simulator-based evaluation to investigate the effects of hemianopia
on lateral lane position and time out-of-lane for specific road segments.
Methods: Twelve patients with complete homonymous hemianopia but without
visual neglect (6 left LH, and 6 right RH) were compared to 12 age and gender casematched normally-sighted (NS) drivers. Participants drove for about 60 minutes in a
high-fidelity simulator on two occasions, one week apart. Each session included city
driving (30mph) and rural driving (60mph) with a variety of traffic situations. The
average and standard deviation (variability) of the lateral lane offset (LLO) from the
center of the travel lane (3m wide), and percent time out of lane (PTOL) were evaluated
for straight road segments (city and rural), right and left curves (city and rural), and
right and left turns (city only).
Results: There were significant differences in LLO between RH and NS drivers for
city and rural straight segments (p = 0.028) and rural right curves (p = 0.028); their
LLO was (on average) 0.2m to the left of NS drivers. By comparison, LLO of LH drivers
was similar to that of NS drivers for straights and curves (p = 0.6), but was 0.8m to the
right of NS drivers in left turns (p = 0.05). Both RH and LH drivers had more variable
LLO than NS drivers (p = 0.02). All drivers (RH, LH, NS) tended to “cut the curve”
with the greatest left-LLO in city left curves (LH -0.50m, RH -0.67m, NS -0.63m) and
the greatest right-LLO in rural right curves (LH 0.48m, RH 0.22m, NS 0.66m). For city
left curves, left-PTOL varied widely within each vision group (from 0 to 73-80%), and
there were no between-group differences. However, for rural right curves, right-PTOL
was higher for LH than both RH and NS drivers (19, 5, 8% respectively, p = 0.04).
Larger LLOs were associated with higher PTOL for both hemianopic and NS drivers
(Spearman rho > 0.78 p < 0.003).
Conclusions: Even with a modest sample size, our results provide evidence that
drivers with hemianopia adopted a lane position with a bias away from the blind
side. These effects varied individually, with segment type, and were more apparent
for right than left hemianopes. However, with the exception of rural right curves,
hemianopes did not spend a greater percent time out of lane than the NS drivers on
the analyzed straight and curved road segments.
CR: E. Peli, None; A.R. Bowers, None; A.J. Mandel, None; R.B. Goldstein, None.
Support: NIH grants EY12890 and EY14723; Center for Innovative Visual Rehabilitation,
Boston VA Medical Center (J. Rizzo)
4108 - A85
Development of a Scale to Measure Reading Ability
S.E. Hassan1, G.D. Barnett2, R.W. Massof 2. 1School of Optometry, Indiana University,
Bloomington, IN; 2Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD.
Purpose: When crossing an unsignalized street, pedestrians must judge gaps
in vehicular traffic to allow enough time for them to reach the other side of the
street before an approaching vehicle reaches them. Due to a lack of psychometric
methods for measuring the street-crossing decision variable, little is known how
well pedestrians can judge differences in gap duration based on using visual and/or
auditory information. The aim of this study was to validate a new metric for assessing
the discriminability of different gap durations based on using different amounts of
visual and auditory information.
Methods: Using a 5 point rating scale, safety ratings for vehicular gaps of different
durations were measured along an unsignalized, two-lane street of one-way traffic.
Safety ratings were collected from 32 subjects: 12 normally sighted, 10 visually
impaired and 10 blind subjects for 7 different gap times under three sensory test
conditions: (i) visual and auditory information; (ii) visual information only; and (iii)
auditory information only. Receiver Operating Characteristic (ROC) curves were
fitted for all possible gap pairs and sensory test conditions and the discriminability
(d’) of the street-crossing safety decision variable for all gap pairs and sensory test
conditions was calculated as the area under the ROC curve.
Results: We found that our data conform to the three underlying principles of
ROC analysis. Specifically, the underlying distributions of the decision variable
are continuous, monotonic and are unbounded. Using the dissimilarity matrix of
d’ values (which were computed relative to each of the other gap times), in a one
-dimensional scaling model, we estimated the means of each distribution of the
decision variable relative to a “center of gravity” (COG). When plotting the means of
the distributions against gap time, the data are best described as an ogive function
symmetric about the COG.
Conclusions: Our analysis of the data strongly suggests that ROC analysis can be
successfully applied to assessing the contributions of auditory and visual information
to street-crossing decision making. Our finding that an ogive function best describes
the relationship between the means of the distributions of the decision variable and
gap time suggests that the decision variable is not discriminable across gap times
below and above a certain value (gap time). Thus all gap times below a certain value
will all be classified by the subject as being “unsafe” and all gap times above a certain
value will be classified as being “safe”.
CR: S.E. Hassan, None; G.D. Barnett, None; R.W. Massof, None.
Support: NIH Grant R03EY014874-03
4109 - A86
The Relation of Patient-Reported Reading Ability to Reading Capability
Measures in Low Vision
A. Cheong1, G. Legge1, S.-H. Cheung2, R. Massof 3. 1Dept of Psychology, University
of Minnesota, Minneapolis, MN; 2Dept of Psychology, University of Hong Kong,
Hong Kong, Hong Kong; 3Wilmer Eye Institutie, Johns Hopkins University,
Baltimore, MD.
R.W. Massof. Ophthalmology, Johns Hopkins Wilmer Eye Inst, Baltimore, MD.
Purpose: The Guide for Evaluation of Visual Impairment has argued the case for
developing “ability scales” that reflect the impact of visual impairment on important
everyday “abilities” including reading. We propose a reading ability scale with
anchoring values of 0 for no reading ability and 100 for normal reading ability, to
represent the reading ability of subjects with age-related macular degeneration (AMD)
and other forms of low vision.
Methods: We analyzed MNREAD data for 46 subjects with AMD and 46 young adults
with normal vision. The raw data were fitted with a nonlinear mixed effects model
to estimate the log reading speeds at 11 print sizes (0 to 1.0 logMAR). An individual’s
reading ability score (RAS) is defined to be the sum of the estimated log reading speeds
across this set of print sizes, divided by the mean summed value for the group of
young, normal adults, and multiplied by 100. RAS was evaluated by Rasch analysis
and Principal Component Analysis. We compared the RAS values of the AMD subjects
for unaided reading and for reading with a prescribed stand magnifier across the
same range of physical print size. The goal of this comparison was to evaluate the
change in overall reading function due to magnifier use.
Results: Psychometric analysis indicated that the RAS was monotonically related
to a hypothetical (latent) reading-ability variable. RAS values for unaided reading
by our AMD subjects ranged from 5 to 89 (with a median of 42.5). Their RAS values
were significantly correlated with critical print size, reading acuity, distance visual
acuity, and contrast sensitivity (p<0.05). With the use of magnifiers, the median RAS
values increased significantly from 42.6 to 72.2 (p<0.01).
Conclusion: RAS values on the new reading ability scale provide a single-valued
score that represents an individual AMD subject’s reading ability with reference
to standard normally sighted readers. The RAS is responsive to changes in reading
performance with the use of magnifiers. It may be a useful outcome measure for
evaluating the merits of rehabilitation or therapeutic interventions intended to improve
visual function.
CR: A. Cheong, None; G. Legge, None; S. Cheung, None; R. Massof, None.
Support: EY 002934
Purpose: To determine how measures of reading capability estimated from reading
performance are related to measures of reading ability estimated from patient
reports.
Methods: Reading speed in words per minute was measured in 109 low vision patients
at 14 print sizes ranging from 0.4M to 8M in 0.1 log unit steps using MNRead. The
same patients were asked to rate the difficulty of a subset of 120 reading tasks in the
Activity Inventory. Maximum reading rate, log reading threshold, and the log of the
ratio of critical print size to reading threshold were estimated from a least-squares fit
of a template function to each patient’s reading speed vs. print size data. Log reading
speeds were binned into 8 ordinal categories and Rasch analysis was performed on the
binned data, treating each print size as a separate item, to obtain estimates of reading
capability on an interval scale for each patient. Rasch analysis also was performed
on the difficulty ratings of the reading tasks to obtain an estimate of self-perceived
reading ability on an interval scale for each patient.
Results: Item measures estimated by Rasch analysis of the reading speed data were
linear with log print size. Mean square fit statistics indicated that both estimated item
measures and estimated person measures of reading capability are unidimensional
and valid. Estimated reading capability measures were strongly correlated with the
log reading threshold (r = -0.91), moderately correlated with maximum log reading
rate (r = 0.38), and weakly correlated with the log ratio of the critical print size to the
reading threshold (r = -0.21). The mean square fit statistics for both item and person
measures of self-perceived reading ability were shown to be unidimensional and
valid. Estimated measures of self-perceived reading ability were moderately correlated
with estimated measures of reading capability (r = 0.55), with a strong linear trend
in the relationship between the two variables. Self-perceived reading ability was
moderately correlated with log reading threshold (r = -0.42) and maximum reading
rate (r = 0.30), and weakly correlated with the log ratio of critical print size to reading
threshold (r = -0.21).
Conclusions: A single summary measure of reading capability estimated from
reading speed vs print size is influenced primarily by the patient’s reading acuity
and secondarily by the patient’s maximum reading rate. Self-perceived reading ability
depends on reading capability, as estimated from performance measures, but also is
influenced by other variables independent of capability.
CR: R.W. Massof, None.
4106-4109
4110 - A87
Training Reading Performance Might Improve Depression in Low Vision
Patients
4111 - A88
Hierarchical Linear Modeling of Psychological Factors That Influence Coping
With Low Vision
M.B. Coco1A, J. Pastor Jimeno1B, I. Fernández2,3, R. Coco1A, R. Cuadrado1A, J. de Lázaro1A.
A
IOBA , Low Vision, BIOBA, University of Valladolid, 1University of Valladolid,
Valladolid, Spain; 2CIBER BBN, Valladolid, Spain; 3IOBA, University of Valladolid,
Valladolid, Spain.
W. Wittich1A,2, J.B. Santo3, J. Renaud4A,5, M.-C. Wanet-Defalque 6,4A, N. Robillard4B, O.
Overbury1B,4A. ANeurology & Neurosurgery - Neuroscience, BOphthalmology,
1
McGill University, Montreal, QC, Canada; 2Lady Davis Institute for Medical
Research, Montreal, QC, Canada; 3Psychology, Concordia University, Montreal,
QC, Canada; ASchool of Optometry, BOphthalmology, 4University of Montreal,
Montreal, QC, Canada; 5Faculté de médecine et des sciences de la santé, Université
de Sherbrooke, Sherbrooke, QC, Canada; 6Institute Nazareth et Louis Braille,
Montreal, QC, Canada.
Purpose: It is accepted that in low vision patients, reading training techniques may
improve the visual performance allowing to achieve important goals for their daily
life activities. But most of these patients have also variable degrees of depression
that might improve with visual success. The goal of this work has been to verify, in
a small sample, this hypothesis.
Methods: 21 patients with central field defects were invited to follow a low vision
protocol exam including: near Visual Acuity (VA), refraction and magnification. Four
training sessions of 30 minutes were performed for reading performance, speed and
comprehension using a reading program specially designed for this work. The grade
of anxiety and depression were also measured before and after the training using
the Spielberger Scale and Yesevage Scale for the Older respectively. Finally, patients
were asked to answer a quality of life questionnaire (WHOQoL-Bref) to find out the
influence of their vision loss on their daily activities before and after the training.
Non parametric tests have been used for statistical analysis.
Results: Twenty-one patients were studied. Most of them (n=19) had ARMD. Mean
age was of 78.6 years (SD±7.7). There was a statistically significant improvement
(p=0.0018) in near VA. Initial VA was 1.117 M (metric scale) (SD±0.6029) and final VA
was 0.744M (SD±0.1653). There were statistically significant differences for reading
speed (RS) measures in visit number 4 (p=0.0001). Mean of initial RS was of 54.10 words
per minute (wpm) (SD±20.89) and mean final RS was of 98.25 wpm (SD±33.76). There
were also statistically significant differences in 9 of the 10 questions of the Yesevage
Scale for depression after the training (p=0.05).
Conclusions: Training programs get a better reading performance in some patients with
central vision loss and benefit their quality of life. But reading training programs can
be also an important tool to motivate the autonomy of the visually handicapped, which
will imply an improvement in the grade of depression of patients with central vision
loss. Further studies will be necessary to confirm these preliminary findings.
CR: M.B. Coco, None; J. Pastor Jimeno, None; I. Fernández, None; R. Coco, None; R.
Cuadrado, None; J. de Lázaro, None.
Support: Junta de Castilla y León, Biomedicina. Spain
4112 - A89
Relationship of Visual Function and Everyday Task Functional Vision in People
With RP
R.A. Schuchard, C. Barnes, C. Hall. Rehabilitation R&D CoE, VA Rehabilitation R&D
CoE, Decatur, GA.
Purpose: To determine the relationship between visual function and functional
vision in everyday tasks over repeated testing for two years in people with restricted
visual fields due to RP.
Methods: Visual functions (ETDRS acuity, SKILL chart near acuity and dark acuity,
CRT presented Grating acuity, Dynamic Visual Acuity, Pelli-Robson contrast
sensitivity, Humphrey Visual Fields, SLO Macular Perimetry, flicker sensitivity, and
motion sensitivity) were tested binocularly in 30 people with visual fields 20 degrees or
less due to RP (retinitis pigmentosa). Functional vision (MNRead reading performance,
Pepper Test reading performance, Dynamic Visual Fields, Face Recognition, Visual
Search of normal scenes and artificial scenes (where’s Waldo type), and mobility in
a controlled lab environment) was tested binocularly in the same people. Self-report
outcome measures included the VA-28, mobility assessment, and falls history.
Results: Subjects had median visual acuity of 0.42 logMAR (range: 0.00 to 1.68) and
median contrast sensitivity of 1.00 logcontrast (range: 0.00 to 1.75). All subjects had
some visual function deficits in the central 20 degrees as well as restricted visual
fields. Median near/dark acuity was 0.42/2.00 logMAR. Median MNRead/Pepper
average maximum reading rate was 180.0/81.4 (range: 0/0 to 342/109) words per
minute. Median correct face recognition was 79 (range: 0 to 96) out of 96 faces. Median
modified dynamic gait index was 19 (range: 9 to 24). Median normalized dynamic
visual acuity was 0.16 (range: 0.09 to 0.37). Dynamic visual field times were from 0.60 to
8.2 seconds (95% of normally sighted subjects have times of 1.0 second or less). Subject’s
self-reported ratings of abilities, independence and satisfaction of the 28 everyday
functional tasks were not significantly related (contingency table analysis). Regression
analysis (linear and Ordinal logistic) found that the functional vision and self-report
outcome measures were more strongly related (if significantly related; p > 0.05) to
dynamic visual acuity and dynamic visual field times than to other visual function
measures like visual acuity, contrast sensitivity, or visual field loss. Further analysis
of the relationships between visual function and functional vision in everyday tasks
will be presented. Repeated measures for 10 subjects that had at least four testing
sessions over two years will also be presented.
Conclusions: Measures of Dynamic Visual Function may be better outcome measures
of the effect of vision loss on everyday function than standard visual function
measures.
CR: R.A. Schuchard, None; C. Barnes, None; C. Hall, None.
Support: VA Rehab R&D Service
Purpose: To investigate whether patient characteristics can explain successful coping
with low vision in individuals that qualify for and/or have accessed rehabilitation
services.
Methods: Over a 9-month period, 289 patients from 4 urban ophthalmology
departments, ranging in age from 26 to 100, completed psychological and demographic
questionnaires (in English or French). A two-level hierarchical linear model was used
to analyze the data. At level 1, within-person variability on coping scores (Brief COPE)
was predicted by variables such as depression (CES-D) and visual functioning (VF-14).
At level 2, participant characteristics (age, living distance, awareness and/or use of
rehab services, visual acuity, etc.) were entered to predict variability at level 1.
Results: At level 1, a significant interaction emerged, whereby high levels of visual
functioning predicted better coping quality; however, this relationship was only
present for individuals with low depression scores. At level 2, an interaction effect
of living distance from rehabilitation services and visual impairment level indicated
that individuals that had to travel further showed improved coping only when their
impairment was more severe. In addition, increased age indicated poorer coping
quality, while a statistical trend indicated that having accessed vision rehabilitation
services may improve coping quality.
Conclusions: It is not surprising that increased depression levels are detrimental
to visual functioning as well as coping with low vision, especially for an elderly
population. However, lowering depression will have beneficial effects on multiple
aspects of the lives of these individuals. It can be speculated that accessing rehabilitation
services, which should include psychological support for depressed individuals, can
benefit both visual functioning and perceived coping quality, especially for seniors
with severe impairment in rural areas.
CR: W. Wittich, None; J.B. Santo, None; J. Renaud, None; M. Wanet-Defalque,
None; N. Robillard, None; O. Overbury, None.
Support: Reseau Vision/FRSQ & INLB Partnership
4113 - A90
Colored Filter Lens Preferences in Low Vision Patients
S. Khan1,2, W.M. Jay3. 1Deicke Center for Visual Rehabilitation, Wheaton, IL; 2Illinois
Eye Institute, Chicago, IL; 3Loyola Medical Center, Chicago, IL.
Purpose: The prescription of colored filter lenses is a regular feature of low vision
rehabilitation. Manufacturers recommend colored filter lenses based on primary
ocular diagnosis. Nonetheless, many vision rehabilitation specialists evaluate a
wider array of colored filter lenses in a trial-and-error fashion before prescribing.
This technique can be time-consuming. The purpose of this study was to investigate
whether following the manufacturer’s recommendations would be more efficient. This
was done by determining whether a group of patients selected a colored filter lens
recommended by the manufacturer for their primary diagnosis even when offered
alternative options. The objective benefits of colored filter lenses are controversial in
the literature. For this reason, the effect of the prescribed colored filter lenses on both
qualitative and quantitative vision was also measured.
Methods: The best corrected visual acuities and contrast sensitivity of eight patients
with visual impairment were measured. The primary diagnosis of each patient was
one of three common ocular conditions: age-related macular degeneration, retinitis
pigmentosa, and diabetic retinopathy. Each patient was asked to rank their preference
for five colored filter lenses selected from the recommendations made by NoIR Medical
Technologies for the three diseases. The lenses included the U68 (light orange),
U50 (yellow), U32 (grey-grey-green), U88 (light plum) and U40 (light amber). These
colored filter lenses are available as UVShield fitovers, lenses designed to fit over the
patient’s glasses. The patients were not told which lenses had been recommended for
their primary diagnosis. Best corrected visual acuity and contrast sensitivity were
re-measured once a fitover had been chosen.
Results: All subjects identified one pair of colored filter lenses as better than the other
four choices. Four of eight chose a filter that was on the NoIR Medical Technologies
list of recommendations for that primary diagnosis. Only two of eight demonstrated
an improvement in objective measurements of vision (one in visual acuity, and the
other in contrast sensitivity).
Conclusions: Only half the patients studied chose a pair of colored filter lenses that
was on the list of the manufacturer’s recommendations for their primary diagnosis.
Subjective trial-and-error of a variety of colored filter lenses appears to be the best
approach. The vision rehabilitation specialist should refrain from prescribing lenses
based solely on the manufacturer’s recommendations.
CR: S. Khan, None; W.M. Jay, None.
Support: None
4110-4113
4114 - A91
Curved Objects May Enhance Visual Accessibility
C.S. Kallie, G.E. Legge, A.M.Y. Cheong, H. Park. Psychology, University of Minnesota,
Minneapolis, MN.
Purpose: We define visual accessibility as the use of vision to travel efficiently and
safely through an environment, to perceive the spatial layout of key features in the
environment, and to keep track of one’s location in the layout. The detectability of
objects is an important component of visual accessibility. Three important factors
interact to determine detectability of objects - illumination, surface characteristics
(such as color, contrast and reflectance), and 3D geometry (shape and size). The goal
of this study was to examine how the detection of simple convex objects (boxes and
cylinders) is influenced by color (gray and white) and lighting condition (overhead
room illumination and side illumination from artificial windows). We predicted that
white objects in front of a gray background will be more visible than gray objects unless they are illuminated from the side. Side illumination will cause cylinders to
be more visible than boxes (when boxes are positioned frontal-planar), even when
cylinders are gray and boxes are white. The curved nature of cylinders provides
additional contrast information, in the form of a luminance gradient, providing a
basis for the prediction that cylinders are more detectable than (frontal-planar) boxes
when illuminated from the side.
Methods: Eleven normally sighted college students made detection judgments yielding
d’ for the presence or absence of real target objects in a real room. The subjects had
simulated acuity reduction produced by blur glasses producing an average monocular
acuity of 20/675. The rectangular boxes and curved cylinders had heights of 2, 4 and
6 ft, and were viewed from distances of 10, 17 and 24 ft. There were two lighting
conditions: moderately uniform overhead room illumination, and an artificial window
illuminating the subject and objects from the side.
Results: Cylinders were more visible than boxes in overhead illumination and window
illumination, but the difference was greater with window illumination. In most
conditions, white objects were more visible than gray objects; however, gray cylinders
were actually more visible than white boxes in artificial window illumination.
Conclusions: Curved surfaces provide reflectance gradients that are helpful
in detectability from a wider range of viewpoints in the presence of directional
illumination than objects with flat surfaces. This interaction of 3D geometry and
illumination may significantly influence the detection of objects by individuals with
low vision.
CR: C.S. Kallie, None; G.E. Legge, None; A.M.Y. Cheong, None; H. Park, None.
Support: NIH Grant 1 R01 EY017835-01
4115 - A92
Does Visual Acuity Form a Barrier for Ophthalmologists to Refer to Low Vision
Rehabilitation Services?
M.-C. Wanet-Defalque1, W. Wittich2A,3, J. Renaud4A, S. Dubuc4A,3, N. Robillard4B,
O. Overbury2B,4A. 1Institute Nazareth et Louis Braille, Longueuil, QC, Canada;
A
Neurology & Neurosurgery - Neuroscience, BOphthalmology, 2McGill University,
Montreal, QC, Canada; 3Lady Davis Institute for Medical Research, Sir Mortimer
B.Davis Jewish General Hospital, Montreal, QC, Canada; ASchool of Optometry,
B
Ophthalmology, 4University of Montreal, Montreal, QC, Canada.
Purpose: Ophthalmologists’ referral patterns to visual rehabilitation may be influenced
by numerous factors. This study examined demographic characteristics of patients
receiving services in urban, university-affiliated ophthalmology departments. The
main issue centered on the patients’ awareness of low vision clinics and full-service
agencies providing assistive devices and training for visually impaired people. An
additional aim of this study was to determine whether ophthalmologists preferentially
refer patients for rehabilitation services, based on their visual acuity.
Methods: Out of ca. 10 000 reviewed patient charts, approximately 10% of this
population met the eligibility criteria for vision rehabilitation (VA less than 20/70 or
visual field less than 60 degrees in the better eye, respectively). To date, 326 visually
impaired people, ranging in age from 26 to 100, have been recruited. They provided
information regarding demographic variables, such as age, income, educational
level, etc.
Results: Three groups were identified based on their response to awareness and/or
usage of vision rehabilitation services: those who were not aware of these services (n
= 91, 28%), those who were aware and chose not to follow through on the referral (n =
41, 12%), and those who were referred and ultimately received services (n = 194, 60%).
Overall, 72% of eligible individuals were aware of vision rehabilitation services. Visual
impairment was divided into three categories - mild (20/70 to < 20/200), moderate
(20/200 to 20/400). The results indicate that only 57% of the patients with mild visual
loss were informed about rehabilitation services, as opposed to 73% and 87% in the
moderate and severe groups, respectively.
Conclusions: Generally, patients’ awareness of rehabilitation services was surprisingly
high. The pattern of referral, however, clearly demonstrated a bias toward referring
late in the impairment process which, in turn, may have significant implications on
patients’ potential success in rehabilitation. This is of particular importance in the
case of seniors affected by age-related visual disorders.
CR: M. Wanet-Defalque, None; W. Wittich, None; J. Renaud, None; S. Dubuc,
None; N. Robillard, None; O. Overbury, None.
Support: Funding proided by FRSQ/Reseau & INLB
4116 - A93
Patterns of Referral of AMD Patients for Low Vision Intervention in the AntiVEGF Era
4117 - A94
Prevalence and Causes of Low Vision and Blindness in an Isolated Southern
Island of Japan: The Kumejima Study
R.B. Schartz1A,2, J.T. Thompson1B, R. Sjaarda1C, J.S. Sunness1A. ARichard E. Hoover
Rehabiliation Services for Low Vision and Blindness, BRetinalSpecialists, CRetina
Specialists, 1Greater Baltimore Medical Center, Baltimore, MD; 2Johns Hopkins
University School of Medicine, Baltimore, MD.
S. Sawaguchi1, Y. Nakamura1, H. Sakai1, A. Iwase2, A. Tomidokoro3, M. Araie3.
1
Ophthalmology, Ryukyu Univ School of Medicine, Nishihara-Cho, Japan;
2
Ophthalmology, Tajimi Municipal Hospital, Tajimi, Japan; 3Ophthalmology,
University of Tokyo Graduate School of Medicine, Tokyo, Japan.
Purpose: To see how the availability of Lucentis affected the referral of patients for
low vision intervention
Methods: A retrospective review of all patients newly referred from a busy retinal
practice for low vision consultation. Data of patients referred from 7/05-6/06 (yr1,
pre-lucentis), and 7/06-6/07 (yr2, lucentis available) were compared.
Results: In yr1, 24 patients with choroidal neovascularization (CNV) were referred for
LV. In yr2, 12 patients with CNV were referred. There was a trend for those patients
referred in yr2 to have worse vision than those in yr1 (Mean best-corrected logMAR
VA yr1-0.67, yr2-0.86, p=0.06; mean Pelli-Robson contrast sensitivity (PRCS) yr1- 1.04,
yr2- 0.84, p=0.04; magnification to read 1M text ; power to read 1M words yr1 6D, yr2 9D,
p=0.07). (The visual acuities by the referring doctor measured on average 0.11 logMAR
units worse than this best-corrected measure, with 14 patients having 2 or more lines
of improvement in best-corrected VA as compared with the referring acuity.)
In yr1 and yr2, 18 patients and 11 patients with conditions other than CNV were
referred for consultation respectively. For these nonCNV patients, there was no
significant difference between groups for VA (mean best-corrected VA yr1-0.62, yr
2-0.46, p=0.33 or contrast sensitivity (mean PRCS yr1-1.00, yr2-1.10, p=0.41), though
the yr2 group tended to have slightly better vision.
Conclusions: While the use of lucentis puts visual acuity in a zone more favorable for
successful low vision intervention, patients with better acuities may not be referred
for low vision evaluation despite their visual impairments and the fact that without
low vision intervention, they are having difficulty with reading and other ADLs. The
frequent visits required for monthly injection, the tendency to wait until a course of
therapy is complete before referring patients, and a lesser appreciation for the need
for low vision intervention may be factors in explaining this.
CR: R.B. Schartz, None; J.T. Thompson, None; R. Sjaarda, None; J.S. Sunness,
None.
Support: None
Purpose: To determine the prevalence and causes of low vision (LV) and blindness
(BLD) in the adult population of an isolated southern island of Japan.
Methods: A population-based ophthalmological survey was conducted from March
2005 to August 2006 in Kumejima Island, located at 26° N, 126°’E in the East China Sea.
Of all 4632 residents with age of 40 yrs or older, 3762 (response rate, 81.2%) underwent
screening examination including measurement of the best-corrected visual acuity
(BCVA) with a Landolt ring chart at 5 m. LV and BLD were defined as BCVA in the better
eye worse than 20/60 to a lower limit of 20/400 and worse than 20/400, respectively
(World Health Organization [WHO] criteria) and worse than 20/40 but better than
20/200 and 20/200 or worse, respectively (United States [US] criteria).
Results: The overall prevalence of LV according to the WHO and US criteria was 1.09%
and 1.67%, respectively, with leading causes of cataract (0.33%), retinitis pigmentosa
(0.17%), diabetic retinopathy (0.11%). The overall prevalence of BLD according to the
WHO and US criteria was 0.39% and 0.75%, respectively. The primary causes were
retinitis pigmentosa (0.17%) and glaucoma (0.11%). Those of monocular LV were
cataract (1.10%), corneal opacity (0.19%), and retinitis pigmentosa (0.17%), while those
of monocular BLD were cataract (0.29%), trauma (0.23%), and glaucoma (0.22%).
Conclusions: The prevalence of LV and BLD in adult residents in a southern island
of Japan was 1.5 to 3 times higher than those in Tajimi City, an urban city in Japanese
Main Land (Iwase et al. Ophthalmology
CR: S. Sawaguchi, None; Y. Nakamura, None; H. Sakai, None; A. Iwase, None; A.
Tomidokoro, None; M. Araie, None.
Support: None CT: www.umin.ac.jp/ctr/index/htm, sshoichi@u-ryukyu.ac.jp
4114-4117
4118 - A95
Impaired Vision Among Elderly Living in a Nursing Home in Norway
I. Langeggen1, H.K. Falkenberg1A. ADepartment of Optometry and Visual Science,
1
Buskerud University College, Kongsberg, Norway.
Purpose: The Norwegian health care act requires all nursing homes to provide health
care, including visual care, to their residents. We wanted to evaluate the visual status
of residents at Eikertun nursing home in Norway.
Methods: Habitual distance and near logMAR visual acuity, near log contrast
sensitivity (MARS test), refractive error, and reading speed was tested in 25 residents
(aged 72-100 years) who participated with informed consent. A questionnaire was
used to assess the residents own experience of visual function at distance and near,
and visual orientation within and outside of the nursing home. All measurements
were performed by an optometrist.
Results: The visual status of the residents in Eikertun nursing home is poor. Mean
habitual visual acuities were 0,64 +/- 0,19 OD and 0,63 +/-0,27 OS which improved to
0,50 +/-0,2 OD and 0,52 +/- 0,2 OS (paired t-test; OD p<0,05, OS p<0.08)). Even after
refraction are 17 of the residents close to WHOs definition of low vision.
19 residents reported problems with reading newspapers. Habitual near visual acuities
were 0,78 +/- 0,12 OD, 0,73 +/-0,15 OS . 3 residents reported to use a magnifier to perform
near tasks. Near contrast sensitivity are also impaired (1,04 +/- 0,2 OD, 1,06 +/-0,1 OS)
compared to visually healthy adults above age 60 years (log CS 1,68). Reading speeds
were also poor and only 7 completed the test..
Neither of the residents reported difficulty in recognizing faces or orienting themselves
in familiar surroundings, however everybody was guided by staff to and from the
consulting room. All residents but two, were given new glasses and 5were referred
to an ophthalmologist and the in-house general practitioner and staff were notified
of the findings.
Conclusions: Visual status among residents in Eikertun nursing home may be
improved by new spectacles and visual aids. The finding that most of the residents
showed improved function with new glasses underscores the importance of regular
eye care services, and that it is necessary for nursing homes to find good routines for
providing this service. In addition there is a need for information about impaired vision
among nursing home staff to improve the life quality of nursing home residents.
CR: I. Langeggen, None; H.K. Falkenberg, None.
Support: SHDir Norway
4118
Wednesday, April 30, 3:00 PM - 4:45 PM Floridian Ballroom A Paper Session Program Number Range: 4510-4516
466. Optical Imaging of the Retina Organizing Section: VI Contributing Section: AP, BI, MOI
4510 - 3:00PM
Dual Wavelength Confocal Adaptive Optics Scanning Laser Ophthalmoscope
(AOSLO)
4511 - 3:15PM
Functional Imaging of Cone Photoreceptors Using Ultrahigh Resolution Optical
Coherence Tomography and Adaptive Optics
Y. Zhang, P. Tiruveedhula, A. Roorda. School of Optometry, University of California,
Berkeley, CA.
B. Cense, R.S. Jonnal, J. Brown, W. Gao, D.T. Miller. School of Optometry, Indiana
Purpose: To facilitate in-vivo study of retinal function at cellular level and improve
retinal imaging fidelity.
Methods: We designed an AOSLO with two low coherence light sources of wavelengths
680 nm and 840 nm. The two beams share the same scanning optics and adaptive optics
(AO), but are independently controlled by acousto-optical modulators (AOM). Two
photo-detectors were optimized for photon detection in two scanning channels. The
840 nm source produced real-time retinal images with enhanced brightness, contrast
and spatial resolution; while the 680 nm source presented AO corrected light stimuli
on the retina. The positions of the source, the retinal plane and the photo-detector
were aligned to be conjugate with each other in both channels. The eye’s longitudinal
and transverse chromatic aberrations between 680 nm and 840 nm were minimized
by adjusting the 680 nm source and its detector, ensuring that both beams focus
transversely and longitudinally on the same point of interest in the retina.
In high resolution functional imaging, where precise placement of visible light stimuli
on the retina is required, the position of interest can be defined in real-time using
images taken with the 840 nm source.
To achieve compound wavelength imaging, the beams from the two light sources
were modulated so that they alternately presented on the forward and return path
of each scanning cycle thereby scanning the same retinal area quasi-simultaneously
at 30 frames/second. The images formed by the two beams were separately recorded,
registered and added.
Results: The dual confocal AOSLO can deliver and maintain a stimulus on a single
cone in real time by precisely tracking the eye movements. With an imaging field
of view of 1.20, the 3-D positioning precision of the light stimulus in the retina of a
macaque eye is 0.21 X 0.21 X 27 micron3; while in the human eye, the accuracy is 1.3
X 1.3 X 60 micron3. Wavelength compounding with two low coherence light sources
was readily realized.
Conclusions: The dual source - retina - detector confocal scheme is a key for
presenting a precise light stimulus in 3-D retinal space and achieving compound
wavelength retinal imaging which can further reduce the interference artifacts in
retinal images.
CR: Y. Zhang, None; P. Tiruveedhula, None; A. Roorda, University of Houston,
University of Rochester, P.
Purpose: Visible flash stimulation of the retina has been reported to trigger fast temporal
variations in the reflectance pattern (“scintillation”) of individual cone photoreceptors,
as for example observed with an adaptive optics (AO) flood illumination camera (1).
Cone “scintillation” has been hypothesized to originate from interference between
reflecting surfaces that straddle the photoreceptor outer segment in conjunction with
optical path length (OPL) changes that occur in the outer segment. The scintillation
duration and pattern suggests an OPL change of 2 μm. To test this hypothesis, changes
in OPL were directly monitored before and after flash stimulation using an ultra-high
resolution optical coherence tomography (OCT) camera equipped with AO. Unlike
prior cameras used to report scintillation, AO-OCT permits resolving the cone outer
segments in all three dimensions with micron resolution.
Methods: The ultra-high resolution OCT system consisted of a Superlum BroadLighter
(T-840-HP, λc = 840 nm, Δλ = 115 nm), a custom achromatizing lens for compensating
the ocular chromatic aberrations across the BroadLighter spectrum, and a 2048
pixel linescan detector in a spectral-domain OCT configuration. The OCT system
acquired up to 30,000 A-scans/s. The AO consisted of a Shack-Hartmann wavefront
sensor, a 37-element AOptix deformable mirror and a 144-element BMC deformable
mirror in a woofer-tweeter configuration. Volume scans up to 3° by 3° were acquired
through a 6.6 mm pupil, with dynamic AO compensation, and of retinal tissue near
the fovea. Bleaching of cone photoreceptors was realized with a single 400 μs flash
from a xenon flash lamp.
Results: Change in the outer segment OPL, as measured with the AO-OCT camera,
was found smaller than the coherence length (~2.5 μm) of the OCT light source. The
position of reflective layers could be detected more accurately than the coherence
length, however, through statistical analysis of the acquired B-scans. Such analysis
revealed a small, but significant change in OPL.
Conclusions: Optical path length differences occurring during cone “scintillation”
were observed with ultra-high resolution OCT equipped with AO.
References: 1. R. S. Jonnal et al., Optics Express 15, 19 (2007).
CR: B. Cense, None; R.S. Jonnal, AO-OCT, P; J. Brown, None; W. Gao, None; D.T.
Miller, AO-OCT, P.
Support: NIH Grant EY018339, NIH Grant EY014743
4512 - 3:30PM
Imaging the Inner Retina Using Adaptive Optics
4513 - 3:45PM
In vivo Time-Lapse Fluorescence Imaging of Individual Retinal Ganglion Cells
in Mice
S.A. Burns, Z. Zhangyi, T.Y.P. Chui, H. Song, A.E. Elsner, V.E. Malinovsky. School of
Optometry, Indiana University, Bloomington, IN.
Purpose:To probe the structure of the inner retina using an Adaptive Optics SLO/OCT
combination system. To better characterize the microstructures of the vasculature
and nerve fiber layer.
Methods:An Adaptive Optics system using both SLO and OCT imaging modalities
with an 840 nm (center wavelength) SLD as a light source was used to image the inner
retina of four normal subjects. The wavefront of the eye was corrected using a Boston
Micromachines MEMS deformable mirror and Shack Hartmann sensor operating in
a closed loop at 8 Hz. A Badal optometer was used to correct .ammetropia, as well
as to displace the plane of focus from the photoreceptors to the inner retinal layers.
Imaging emphasized multiple 1.8 x 1.6 deg.loci, at 7 to 10 deg, in both the superior and
inferior fields. The region of interest was guided by a simultaneous, large field SLO
image, that permitted directing the high magnification imaging to selected arteries
and veins for several deg across the retina, forming a large montage to compare to
published histology at several magnifications.
Results:Image quality was excellent. Small features down to 6 microns were
reproducibly visualized over time. At arterio-venous (AV) crossings, there was an
abrupt change in the appearance of the retina. Vessels were joined by a fibrous
membrane, with fibers on the order of 3-8 microns, presumably related to the inclusion
of the vein within the adventitial sheaths of the arteries. At the AV junctions, there
was a marked decrease in the background structures, with a visible ring around the
junction. Near the vessels there were sparse circular or annular white structures,
approximately 20 microns in diameter. These lay along the surface of the nerve
fiber layer as confirmed with AOOCT. These cells were deep to the peripapillary
vasculature, which was readily imaged, and enhanced due to movement of cells
within the capillaries.
Conclusions:Small structures in the inner retina are visualized in high contrast, and
repeatably, using an AOSLO. The same instrument, by merely a change of focus, is
used to locate outer retinal structures, such as photoreceptors. This system allows the
rapid identification and localization of structures, including peripapillary capillaries,
nerve fibers bundles in the nfl, nerve fibers as they cross the vasculature, and support
structures of the vasculature. We can also repeatably image cellular structures along
the surface of the retina, although the histological correlates are not yet known.
CR: S.A. Burns, None; Z. Zhangyi, None; T.Y.P. Chui, None; H. Song, None; A.E.
Elsner, None; V.E. Malinovsky, None.
Support: NIH Grants R01EY14375, R01EY04395
M.K. Walsh, H.A. Quigley. Ophthalmology, Wilmer Eye Institute, Johns Hopkins
School of Medicine, Baltimore, MD.
Purpose: To develop a technique to produce time-lapse images of individual retinal
ganglion cells (RGCs), their dendrites and axons in vivo.
Methods: A standard confocal laser scanning microscope, transgenic mice that
express yellow fluorescent protein (YFP) in a subset of RGCs, and survival anesthesia
techniques were utilized.
Results: The same individual RGCs with their dendritic arbors and axons were
multiply imaged on separate days in vivo in both adult (Figure 1 and Figure 3 left and
middle panels) and juvenile mice. Additionally, the same RGC that was imaged in vivo
could then be located and imaged in fixed retinal whole mount preparations (Figures
2 and 3; right panels show fixed tissue, left panels are images taken in vivo).
Conclusions: We have developed a technique that permits time-lapse imaging of
RGCs and their cellular processes in mammals in vivo for the first time. This novel
technique has many potential applications.
CR: M.K. Walsh, None; H.A. Quigley, None.
Support: Harry A. Quigley Research Award from the Wilmer Eye Institute (MKW);
NIH grants EY 02120 and 01765 (HAQ); Unrestricted support from the Leonard Wagner
Trust, New York, NY (HAQ).
4510-4513
Wednesday, April 30, 3:00 PM - 4:45 PM Floridian Ballroom A Paper Session Program Number Range: 4510-4516
466. Optical Imaging of the Retina Organizing Section: VI Contributing Section: AP, BI, MOI
4514 - 4:00PM
Tracking Transfection of Macaque Retinal Ganglion Cells With AAV2 Viral
Vectors; In vivo Imaging Reveals Differences Between Two Promoters
4515 - 4:15PM
High-Resolution in vivo Retinal Imaging of Glial Cell Endfeet
W.H. Merigan1A, D. Scoles1B, J.J. Hunter1B, B. Masella1B, K.P. Greenberg2, J.G. Flannery2,
R.T. Libby1A, D.R. Williams1B. AOphthalmology, BCenter for Visual Science,
1
University of Rochester, Rochester, NY; 2Molecular and Cell Biology, University of
California, Berkeley, Berkeley, CA.
Purpose: To develop a method for viral mediated gene transfer to primate retinal
ganglion cells using in vivo imaging and histological analysis to track the selectivity
of transfection.
Methods: AAV2 viral vectors containing either chicken beta-actin or connexin (CX36)
promoters driving GFP were injected intravitreally into macaque eyes. The degree of
transfection was monitored in vivo with adaptive optics imaging and histologically
by microscopy
Results: We observed a prolonged delay of several months between intravitreal
injection of the viral particles and visible GFP expression for vectors containing the
chicken beta-actin promoter. GFP expression was first observed in foveal cones at 43
weeks, and only at 57 weeks was GFP visible in an annulus of densely labelled retinal
ganglion cells (RGCs) around the fovea. Histological analysis indicated additional
labeling in the periphery of the retina that was not visible with in vivo imaging,
especially sparse labeling of presumptive Muller cells and RGCs. On the other hand,
AAV vectors of the same serotype and titer containing the connexin promoter produced
rapid onset (2 weeks) and dense labeling of circumfoveal RGCs. This promoter did not
produce transfection of cone photoreceptors. In addition, GFP labeling of peripheral
RGCs, small numbers of Muller cells and some cells in the inner nuclear layer were
found on microscopy.
Conclusions: AAV2 viral vectors containing two different promoters both produced a
striking pattern of dense labeling of RGCs in an annulus around the fovea. However,
results with the two promoters differed in that only the beta-actin promoter produced
labeling of foveal cones, and only the connexin promoter produced a rapid appearance
of GFP in retinal neurons. Transfection of primate RGCs combined with in vivo
imaging at multiple timepoints will be useful for a variety of studies relevant to
human diseases affecting ganglion cells as well as neuroscience investigations of
visual processing.
CR: W.H. Merigan, Bausch and Lomb, F; D. Scoles, Bausch and Lomb, F; J.J. Hunter,
Bausch and Lomb, F; B. Masella, Bausch and Lomb, F; K.P. Greenberg, None; J.G.
Flannery, None; R.T. Libby, None; D.R. Williams, Bausch and Lomb, F; Bausch and
Lomb, Optos, C; Adaptive Optics, P.
Support: Bausch and Lomb, NIH EY014375, NIH EY01319, NSF Science and Technology
Center for Adaptive Optics (coop. agr. no.: AST-9876783 with UCSC), NEI Training
grant EY07125, and Research to Prevent Blindness
H. Song, X. Qi, T. Chui, S.A. Burns. Optometry School, Indiana University,
Bloomington, IN.
Purpose: To explore cellular structures in the living human retina using a high
resolution Adaptive Optics Scanning Laser Ophthalmoscope (AOSLO); to further
establish the AOSLO as a valuable high resolution, in-vivo imaging tool by imaging
different layers and cellular structures in the retina.
Methods: An 840 nm (center wavelength) SLD was used as the imaging light source. The
adaptive optics control of the system was maintained by using a Boston Micromachines
MEMS deformable mirror and Shack Hartmann sensor operating in a closed loop
at 8 Hz. The imaging beam was steered by an 8k Hz horizontal scanner and a 15 Hz
vertical scanner to sweep an imaging region of 1.8 x 1.7 degree on the retina. Real
time video images were collected while focused on retinal veins and capillaries in 4
normal subjects. Images were aligned and averaged using post-processing. The size
and morphology of observed structures related to the blood vessels was compared
to published histology.
Results: In live AOSLO video movies, the appearance of retinal vessels is dominated
by the movement due to blood flow. However, along the blood vessels, at different
depth relative to the never fiber layer, numerous stationary bright spots are also visible.
And for vessels near the inner limiting membrane, other filamentous structures can
be reliably imaged along the surface of blood vessels for all subjects. The size of the
bright spots varies from 10um to 20um, which is comparable to the size of the endfeet
of the retinal astroglia. The filamentous structures connect to the bright spots, and
do not show evidence of blood flow in the live video images, suggesting that they are
not capillaries but astroglial processes. These structures are smaller than the retinal
nerve fiber bundles, which are readily observed. Repeat imaging in one of the subjects
over 3 months indicates that the small structures are stable over time, and therefore
not related to blood constituents.
Conclusions: We believe the bright structures along the surface of retinal blood vessel
are the endfeet of astroglia because of their close similarity to histological data in
terms of their location, size and morphology.
CR: H. Song, None; X. Qi, None; T. Chui, None; S.A. Burns, None.
Support: NIH Grant EY14375, EY04395
4516 - 4:30PM
Reciprocity of Light-Induced Reduction in Retinal Pigment Epithelial
Autofluorescence
J.I.W. Morgan1, J.J. Hunter1, R. Wolfe1, B. Masella1, J.R. Sparrow2, W.H. Merigan1, D.R.
Williams1. 1Center for Visual Science, University of Rochester, Rochester, NY;
2
Department of Ophthalmology, Columbia University, New York, NY.
Purpose: We have previously shown that long exposure to 568 nm at levels below the
ANSI maximum permissible exposure (MPE) produces retinal damage preceded by a
transient reduction in the autofluorescence (AF) of retinal pigment epithelial (RPE) cells
in vivo. We sought to establish the effects of exposure power and duration in producing
this AF reduction as well as the maximum exposure that does not produce a detectable
reduction.
Methods: Macaque retinas were imaged using a fluorescence adaptive optics scanning
laser ophthalmoscope to resolve individual RPE cells in vivo. The retina was exposed to
568 nm light over a square subtending Â½Â° with energies ranging from 1 J/cm 2 to 788
J/cm 2. Exposure power and duration were independently varied to establish their effects
on AF reduction. Pre-, immediately post-, and long-term post-exposure AF images of the
RPE cells were taken over a 2Â° field. The amount of AF reduction was quantified by the
normalized ratio of AF intensity inside to outside the exposure.
Results: In vivo exposures of 5 J/cm 2 and higher caused an immediate decrease in AF.
Subsequent imaging showed either full recovery of AF (exposures of 210 J/cm 2 and
lower) or permanent RPE cell damage at the site of the exposure (exposures of 247 J/
cm 2 and higher). Reciprocity of exposure power and duration held for exposures from
45 seconds to 900 seconds for all conditions. No significant AF reduction was observed
for exposures of 1 J/cm 2.
Conclusions: That reciprocity holds implies that the total energy delivered to the retina,
rather than its distribution in time, determines the amount of AF reduction, consistent
with a photochemical origin. The cause of reduced AF could be, among other things,
A2E photoisomerization or photooxidation. If it is caused by photooxidation, reduced AF
could be associated with retinal damage. We have observed AF reduction with exposures
(5 J/cm 2) 31 times less than the ANSI MPE (155 J/cm 2, thermal limit). The implementation
of safe methods, not only to image the RPE cell mosaic in vivo, but also to deliver high
intensity light to the retina generally requires a better understanding of the cause and
effects of AF reduction.
CR: J.I.W. Morgan, Bausch and Lomb, F; Dual Wavelength Imaging, P; J.J. Hunter,
Bausch and Lomb, F; R. Wolfe, Bausch and Lomb, F; B. Masella, Bausch and Lomb, F; J.R.
Sparrow, None; W.H. Merigan, Bausch and Lomb, F; D.R. Williams, Adaptive Optics,
Dual Wavelength Imaging, P; Bausch and Lomb, F; Bausch and Lomb, Optos, C.
Support: NIH EY014375, NIH EY01319, NSF Science and Technology Center for Adaptive
Optics (cooperative agreement no.: AST-9876783 with UCSC), NEI EY07125, Bausch and
Lomb, Research to Prevent Blindness
4514-4516
Wednesday, April 30, 3:00 PM - 4:45 PM Hall B/C Poster Session Program Number/Board # Range: 4552-4568 / A33-A49
472. Optics and Dynamics of Accommodation Organizing Section: VI Contributing Section: LE
4552 - A33
Mathematical Analysis of Defocus Curves in the Assessment of
Accommodation
4553 - A34
Measured Changes in Accommodative Amplitude With Age Using the Maxwell
Ocular Wavefront Aberrometer
K.H. Edwards1, H. Proskin2. 1Global Clinical Development, Bausch & Lomb,
Rochester, NY; 2Howard Proskin Associates, Rochester, NY.
L.A. Shilliam1A, A.M. Mahmoud1B, R.G. Lembach1B, C.J. Roberts1B. AColleges of Public
Health and Medicine, BOphthalmology and Biomedical Engineering, 1The Ohio
State University, Columbus, OH.
Purpose: The effect of positive and negative lens induced blur on visual acuity has
been used to investigate the potential improvements in depth of field and/or genuine
accommodation with multifocal and potentially accommodating intraocular lenses
(IOLs).
Accommodation is only demonstrated when there is asymmetry in the speed of visual
reduction between positive and negative lens defocus, negative defocus causing less
visual loss in the presence of accommodation.
Methods: The authors investigated a curve fitting algorithm that utilizes separate
best-fit quadratic curves for positive and negative defocus values, subject only to the
constraint that the curves intersect at the zero defocus point. Once the estimated
curves have been established, the respective defocus powers necessary to maintain
a given level of acuity can be extrapolated and the difference between them used to
calculate the effective accommodation.
Results: By using data from defocus assessments of a potentially accommodating IOL,
this methodology provided good assessments of real “accommodation” and could
differentiate this from cases where good near acuity was evident despite a lack of
accommodation, suggesting an enhancement to depth of field.
Conclusions: The mathematical analysis provided objective and reliable assessments
of genuine accommodative effect.
CR: K.H. Edwards, Bausch & Lomb Inc, E; H. Proskin, Bausch & Lomb Inc, C.
Support: None
Purpose: To evaluate the Maxwell Ocular Wavefront Aberrometer as a new device
capable of measuring accommodative response.
Methods: 12 eyes of 6 subjects were prospectively recruited (age range: 26 to
51). Subjects who were pregnant or with a history of hypertension, diabetes, eye
surgery, or eye disease were excluded. The Maxwell Ocular Wavefront Aberrometer
was used to measure both eyes of each subject before and after dilation. Multiple
measurements were taken to allow subject adjustment to the procedure followed by 2
study measurements. The best measurement was chosen based on the subject’s ability
to focus on the stimulus. Accommodative response was measured as the maximum
response minus the minimum response. Linear regression analysis was performed
comparing accommodative response vs. age for both the dilated and undilated states.
Repeated measures analysis of variance comparing dilation status was also performed.
Eyes were also divided into 2 groups: greater than 40 and less than or equal to 40
years of age. Linear regression was performed for accommodative response versus
stimulus in the two groups.
Results: Linear regression of measured accommodative response vs. age showed a
significant decrease in accommodation with age for both the undilated (p<0.0001,
r2=0.8854) and dilated state (p<0.0001, r2=0.8299). Linear regression showed a
significant increase in accommodation vs. stimulus for undilated eyes under 40
(p<0.0001, r2=0.8530), dilated eyes under 40 (p<0.0001, r2=0.8798), undilated eyes over
40 (p=0.0006, r2=0.2270), and dilated eyes over 40 (p<0.0001, r2=0.3093). There was no
significant difference between response in dilated and undilated eyes (p>0.05).
Conclusions: Previous studies with more sophisticated and cumbersome laboratory
techniques have shown characteristic decreases in accommodative response as humans
age. The Maxwell Ocular Wavefront Aberrometer produces results consistent with
these studies when measuring accommodative response vs. age. The response in older
adults is shown to be significantly less than that of younger adults. This device offers
a clinically available and easy to use method for evaluating accommodative response.
Important uses may include objective evaluation of the efficacy of accommodative
restoration procedures.
CR: L.A. Shilliam, None; A.M. Mahmoud, None; R.G. Lembach, None; C.J. Roberts,
Zeimer Group, F.
Support: The National Institutes of Health under Ruth L. Kirschstein National Research
Service Award T32RR023260 from the National Center for Research Resources.
4554 - A35
Objective Measurement of Amplitude of Accommodation Using a Double Pass
Based System
4555 - A36
Desktop Publishing & Validation of a Custom Near VA Chart for Measuring
Accommodative Amplitude.
S. Luque, M. Aldaba, F. Diaz-Douton, V. Lapuente, J. Pujol. Optics & Optometry,
Universitat Politecnica de Catalunya, Terrassa, Spain.
L. Marran1, L. Liu2, G. Lau 3. 1Vision Science Consulting, Fullerton, CA; 2School of
Optometry UAB, Birmingham, AL; 3Clinical Specialist, Visiogen, Inc., Irvine, CA.
Purpose: The aim of our study was to objectively measure the amplitude of accommodation
using a double pass commercial device (OQASTM, Visiometrics, SL). The response was
tested by stimulating accommodation as in Sheard and Donder’s methods and the result
compared to subjective techniques.
Methods: The measurement of the amplitude of accommodation was carried out using a
modified double pass system. A periscope was incorporated to the commercial device to
get a stronger stimulation of the accommodation. The stimulation was obtained by adding
negative lenses up to 4 diopters or bringing the object nearer to the patient and defocus
was measured at 780 nm with OQASTM. In all the cases the subject’s sphere and cylinder
were corrected. When negative lenses are added the subject accommodates to cancel the
generated defocus. Therefore, while accommodation acts the measure remaining defocus
corresponds to the accommodative lag. When the object is presented at different positions
instead of using lenses, the measured defocus is the accommodation produced. A group of
14 people, 10 normal and 4 pseudophakic, were measured using both negative lenses and
proximal object methods. The age ranged from 25 to 60 (mean age 35) and the spherical
refraction from -3.5 to 2 D (mean value -1.25 D). The measurements were correlated using
the same ways of stimulation while subjective techniques were applied.
Results: We did not find statistically significant differences between the two ways of
stimulation when measured objectively. This might confirm that the differences found
between Donder and Sheard method when measure subjectively are due to the change
of the image size on the retina while the stimulation of accommodation is in both cases
similar. The observed differences between object position and defocus measured may be
explained by chromatic differences between target illumination and the wavelength used
by the instrument. Statistically significant differences (0.75 D ± 0,3; p<0.05) were found
between subjective and objective methods which are ascribed to pseudo-accommodation
since pseudophakic eyes also showed similar differences.
Conclusions: We have shown the possibility of using a modified double pass commercial
device to measure the amplitude of accommodation. The technique presented the
advantage of avoiding pupil effect found in subjective methods which enhances the
amplitude of accommodation results because of pseudo accommodation. Furthermore,
the pupil size is not critical and pseudo accommodation can be also objectively estlimated
and included to compute an expected subjective range.
CR: S. Luque, UPC, P; Visiometrics, SL, E; M. Aldaba, None; F. Diaz-Douton, Visiometrics,
SL, E; V. Lapuente, Visiometrics, SL, E; J. Pujol, Visiometrics, SL, I; UPC, P.
Support: MEC (Spain) DPI2005-08999-C02-01
Purpose: Customized visual acuity (VA) assessment can greatly facilitate basic and
clinical vision research. Two obstacles have to be overcome in making a customized VA
chart: to produce it up to specification and to validate it against an accepted standard.
We used desktop publishing to produce near VA charts for repeated measures of
subjective accommodative amplitude in patients implanted with the Synchrony
®AIOL lens (Visiogen Inc. Irvine, CA). There were six charts ranging from 20/20 to
20/63 in 0.1 log unit steps. Each chart had multiple lines of the same acuity level to
prevent memorization (e.g. the 20/20 chart presented several unique lines of 20/20
optotypes in different order and no other optotype size). Each chart had a random
noise background- to maintain a constant spatial frequency profile of the peripheral
accommodative stimulus, a possible improvement over standard VA charts with
multiple acuity levels, where neighboring spatial frequencies are dependent on the
acuity line being viewed. We validated our custom charts against a commercially
available (standard) chart.
Methods: A 1200 dpi canvas was used to take advantage of the high pixel resolution
of modern desktop printers. Pixel accurate bitmaps of Sloan optotypes 20x20 to 90x90
in size were derived from a set of vector graphs and printed on a laser printer. The
physical sizes of the printed optotypes were measured under 15x magnification. Pixels
sizes that closely matched the required sizes of 20/20 to 20/63 optotypes (in 0.1 log
unit steps) at a 40 cm viewing distance were selected. Bitmaps of selected optotypes
were pasted into a canvas with customized format and background. The functional
equivalence of the customized near charts to a standard chart were compared on 10
normal phakic subjects under the age of 40.
Results: At all acuity levels, the physical sizes of the printed custom optotypes deviated
no more than 0.034 log units from that of the standard, satisfying the 0.05 log unit ISO
criterion and demonstrating physical equivalence. Also, at all acuity levels, log unit
differences in the mean target distance for which reliable recognition of letters first
occurred for the custom optotypes compared to the standard were found to be below
the 0.05 log unit ISO criterion, demonstrating functional equivalence. Conclusion:
It is possible, with careful planning and design, to produce customized near VA
assessment instruments that are physically accurate and functionally equivalent to
an accepted standard.
CR: L. Marran, Visiogen, Inc., C; L. Liu, Visiogen, Inc., C; G. Lau, Visiogen, Inc., E.
Support: Visiogen, Inc.
4552-4555
4556 - A37
The Influence of Short Term Near-Spectacle-Correction on Accommodation,
Refractive State, and Eye Alignment in Adults
4557 - A38
Proximal Accommodation During Measurement of Refraction
L. Chen, S. Somani. Advanced Medical Optics, Inc., Santa Clara, CA.
I. Vedamurthy1, W. Harrison1, M. Liu1, I. Cox2, C.M. Schor1. 1School of Optometry,
University of California at Berkeley, Berkeley, CA; 2Scientific Clinical & Medical
Affairs, Bausch & Lomb, Rochester, NY.
Purpose: A pilot study evaluated the effect of short-term first-near-spectacle correction
on the accommodative-stimulus response (ASR) function, accommodative amplitude
(AA), AC/A and CA/C ratios in two adult age groups and determined if changes
in these functions recovered after discontinuing the use of near spectacles for two
months.
Methods: Twenty-four normal subjects in two age groups (21-30 years [n =12] and
38-43 years [n = 12]) completed the study. There were 5 emmetropes, 6 myopes and 1
hyperope in both groups. A Badal optometer and Wheatstone-mirror haploscope were
used to measure the ASR function, AA, response AC/A and stimulus CA/C ratios
before and two months after wearing single-vision reading spectacles for near tasks,
and a third time, two months after discontinuing the use of reading spectacles.
Results: AC/A and CA/C ratios and the linear slope of the ASR function did not change
significantly after wearing near spectacles (p > 0.05). AA, defined as the difference
between the near-point of accommodation (NPA) and the far point (distance refractive
state), did not change significantly with treatment (p > 0.05). However, there was a
hyperopic shift of the ASR function that significantly reduced the NPA (p<0.05), and
lowered the y-intercept of the ASR (far-point refraction). There was no significant
difference between changes observed for myopes and emmetropes. These changes
did not recover after 2 months of discontinuing the use of near spectacles.
Conclusions: The NPA may normally be enhanced by a tonic bias of accommodation
that elevates the entire ASR function and produces a myopic refraction bias. When this
bias relaxes after wearing near spectacles, there is a hyperopic shift of the refractive
state, and a reduction of the NPA, specified from optical infinity, but the AA specified
from the far-point refraction is unaffected. In practical terms, our results suggest
that the prescription of near corrections for incipient presbyopia should be based on
patient symptoms and not solely on patient age.
CR: I. Vedamurthy, None; W. Harrison, None; M. Liu, None; I. Cox, Bausch & Lomb,
E; C.M. Schor, None.
Support: Bausch & Lomb
Purpose: Clinical wavefront sensors and automatic refractors normally use a fogging
fixation target to relax the patient’s accommodation during measurement. However,
this kind of fixation target does not always work well because some eyes may overaccommodate when viewing a static fixation target. This study examined whether
the proximal cue given by a moving fixation target could help relax the patient’s
accommodation during refraction measurement.
Methods: Eight eyes from 4 subjects ranging in age from 21 to 29 were chosen for
this study so that the experiment would be conducted on eyes with a tendency to
accommodate while looking into the instrument. Each subject was aligned to a
wavefront sensor while viewing the fixation target in white light, which was displayed
on a color micro-display screen conjugate with the retinal plane of the eye. The
fixation targets comprised five different movies made from sequences of images and
played at 15 frames per second. Each movie featured a prominent object such as a
baseball, a picture of a globe, etc. placed at the center of the screen, which subtended
a six-degree visual angle. The micro-display was configured at optical infinity. As the
movie progressed the object became progressively smaller. The demagnification rate
was chosen to create a realistic perception of the object moving away from the viewer.
The movies were paused at times to present a static target. Five different movies were
played randomly on the micro-display. No pharmacological agent was used to dilate
the patient’s pupil. Refractive error and higher order aberrations up to the 6th order
in each eye were measured using a Shack-Hartmann aberrometer. Six measurements
of each eye were performed with a static fixation target and 6 measurements of each
eye were performed with a moving fixation target.
Results: When the 8 eyes of the 4 subjects viewed a moving target, the standard
deviation of the refractions in the multiple measurements was significantly smaller
than when the eyes viewed a static target. The average standard deviation across 8
eyes was reduced by 57% when viewing the moving target. The mean sphere power
of 6 of the 8 measured eyes moved towards positive when viewing a moving fixation
target, which indicates improved relaxation of accommodation.
Conclusions: The proximal cues presented by the dynamic target helped to relax
and stabilize the accommodation state of the eyes of this cohort. The perception of
the target moving away from the observer appears to influence the neural system
to command the ciliary and zonular muscles to relax accommodation to the farthest
viewing point of the eye.
CR: L. Chen, Advanced Medical Optics, Inc., E; S. Somani, Advanced Medical
Optics, Inc., E.
Support: None
4558 - A39
Effects of Phenylephrine 5% on Accommodative Response and Ocular
Wavefront Aberrations Variations
4559 - A40
Changes on the Estimation of the Objective Amplitude of Accommodation for
Different Pupil Sizes
J.-J. Gicquel1, J.-L. Nguyen Khoa2, F. Harms3, N. Lopez-Gil4, R. Legras5, D. Lebuisson2,
J.-F. Le Gargasson6. 1Ophthalmology, Jean Bernard University Hospital, Poitiers,
France; 2Ophthalmology, Hopital Foch, Suresne, France; 3Imagine Eyes, Orsay,
France; 4Physics, Laboratorio de Óptica, Universidad de Murcia, Murcia, Spain;
5
Laboratoire Aime Cotton, Universite d’Orsay, Orsay, France; 6Laboratoire de
Biophysique, Université Paris VII, Paris, France.
V. Fernandez-Sanchez1, R. Montés-Micó2, A. Cerviño2, N. López-Gil1. 1Ciencias de
la Visión, Universidad de Murcia, Murcia, Spain; 2Departamento de Óptica,
Universidad de Valencia, Valencia, Spain.
Purpose: To study the effects of phenylephrine 5% topical administration on
accommodative response and optical aberrations variation in young healthy
subjects.
Methods: The research followed the tenets of the Declaration of Helsinki . 28 eyes
from 14 volunteers with spherical equivalent defocus error between -2D and +1D,
no eye disease history and between 20 to 25 years of age, underwent wavefront
measurements with an Imagine Eyes® IRX3 Shack-Hartmann wavefront aberrometer
which included a movable accommodative target. Wavefront data was acquired while
applying 6 different increasing accommodative stimuli, from 0 D to 5 D by steps of 1
D, before and after pupil dilation with Phenylephrine 5%.
Results: The dilation using Phenylephrine 5% was found to larger lag errors in the
accommodative response of about half of the subjects. The total RMS amount of
aberrations above defocus remained stable during accommodation with and without
dilation. Spherical aberration was positive in average in the non accommodated
eye and changed toward negative values with increasing accommodation (p<0.05).
Cylinder axis came closer to 90° as accommodation increased (p<0.05). Although
vertical coma did not significantly vary with accommodation, horizontal coma
increased significantly with accommodation (p<0.05). These changes in aberrations
with increasing accommodation were similar on average in both pupil conditions.
Conclusions: Phenylephrine 5% modifies the accommodative focus response of a
significant proportion of young adult eyes. Wavefront aberrations above defocus
undergo similar variations in both natural and dilated pupil conditions. However
the total RMS error of aberrations above defocus remains relatively constant when
the eye accommodates.
CR: J. Gicquel, None; J. Nguyen Khoa, None; F. Harms, F.Harms is employed by
Imagine Eyes Inc who is the manufacturer of the IRX3 Wavefront Aberrometer used
in this study, I; N. Lopez-Gil, None; R. Legras, None; D. Lebuisson, None; J. Le
Gargasson, None.
Support: None
Purpose: Objective measurement of the amplitude of accommodation (AA) can be
calculated monoculary using certain metrics from aberrometric outcomes obtained
during accommodation stimulation. However, those metrics depend in general on
pupil diameter, which not only varies during accommodation but also with light
room conditions. In this study we analyze whether the objective measurements of AA
undergo a modification when the pupil size of the unaccommodated eye varies.
Methods: We measured ocular aberrations in 20 normal eyes (12 subjects) with ages
ranging from 20 to 42 years using an aberrometer while their accommodation was
stimulated with a target. Target’s vergence varied in a range larger than subject’s
range of vision (steps of 0.5 D). AA was calculated as the mean of three repeated AA
measurements obtained from wavefront outcomes on each subject under two starting
points (unaccommodative state) conditions: (1) dim room light (about 2 cd/m2) and
(2) photopic room light (about 50 cd/m2).
Results: Mean pupil diameter were 6.1 mm and 4.6 mm for condition (1) and (2),
respectively. Although it was found intrasubject AA variations up to more than 1 D
between pupil conditions, the mean intersubject changes for conditions (2) and (1) was
0.13±0.87D. This represents about 5% of reduction (not statistically significant p=0.6)
in the AA of accommodation for condition (2) in relation to (1). A high correlation
(R= 0.93) was found between the AA obtained at both conditions. The changes in
AA found between both conditions were smaller than the mean standard deviation
obtained whiting the 3 AA (0.54 D).
Conclusions: The size of the pupil of the unaccommodated eye (which depends on
the room illumination) does not seem to play a relevant role in the measurement of
the AA. These results agree with the fact that the most important change during
accommodation for the AA is not the change of pupil size but optical aberrations,
especially defocus and spherical aberration.
CR: V. Fernandez-Sanchez, None; R. Montés-Micó, None; A. Cerviño, None; N.
López-Gil, None.
Support: Comunidad Autónoma de Murcia, Fundacion SENECA
4556-4559
4560 - A41
Influence of Accommodative Amplitude and Age on Objective Measurements of
Lag in Children and Adults
4561 - A42
Edinger-Westphal Stimulated Accommodation in Rhesus Monkeys Using a
Pulse-Step Stimulation Model
H.A. Anderson1A, K.K. Stuebing1B, A. Glasser1A, R.E. Manny1A. ACollege of Optometry,
B
Department of Psychology, 1University of Houston-Downtown, Houston, TX.
M. Baumeister1,2A, M. Wendt2A, C. Shooner2B, A. Glasser2A. 1Department of
Ophthalmology, Johann Wolfgang Goethe University, Frankfurt am Main,
Germany; ACollege of Optometry, BDepartment of Biomedical Engineering,
2
University of Houston, Houston, TX.
Purpose: Previously reported data from this lab demonstrates that objectively
measured, trial lens stimulated amplitudes of accommodation are largest in young
children (mean predicted ampl=7.33D) and remain relatively stable from age 3 until
the 20s when amplitude begins to decline rapidly with age. The purpose of this study
is to investigate the influence of age and amplitude upon lag of accommodation.
Methods: Accommodative responses were measured in 101 subjects (3-40 yrs) with
at least 10 subjects in each 5yr age bin. Subjects monocularly viewed a high contrast
target with small print and pictures positioned at 33.3 cm on the near rod of the Grand
Seiko autorefractor. Refractions were measured as the subject kept the target clear.
Accommodative lag was defined as the difference between demand and response.
Four additional demands were tested by introducing minus lenses of increasing power
in the spectacle plane of the viewing eye. Accommodative demands and responses
were adjusted to the corneal plane to account for lens effectivity.
Results: At the 3D demand, the most accurate accommodative response was observed
in subjects 26-30 yrs (mean lag 0.49±0.26D) and the least accurate responses observed
in the youngest subjects (0.94±0.29D). As the stimulus demand approached the
maximum response amplitude for the 26-30yr group (mean predicted ampl=5.83D),
lag increased and the most accurate responses shifted to the 16-20 yr group (0.96±0.51
for 6.52D demand). When response amplitude was essentially constant (3-20 yrs), lag
of accommodation was always greatest in the youngest subjects for all demands and
decreased systematically with increasing age. When accommodative response was
not limited by the response amplitude, the largest mean difference between the most
accurate response and the highest lag was 1.06D and occurred for the 4.80D stimulus
(mean lag 1.74±0.77D ages 3-5, versus 0.68±0.38D ages 26-30).
Conclusions: Accommodative lag systematically decreased from the youngest subjects
until the 20s for all five stimulus demands tested and suggests that the accuracy of
the accommodative system varies throughout childhood independent of the stable
accommodative amplitude that is present throughout these years.
CR: H.A. Anderson, None; K.K. Stuebing, None; A. Glasser, None; R.E. Manny,
None.
Support: NEI T35 EY007024
4562 - A43
Accommodation Dynamics With Adaptive-Optics- Corrected Ocular
Aberrations
Purpose: In recently developed models of human accommodation it has been suggested
that amplitude and dynamics of human accommodation are controlled by pulse-step
signals, modification of which could allow for neural compensation of age-related
changes to the accommodative plant. The aim of this study was to examine the effect
of a pulse-step stimulation paradigm on Edinger-Westphal stimulated, open-loop
accommodation in anesthetized rhesus monkeys.
Methods: One eye each of three rhesus monkeys (age 10 to 12 years) was studied.
Accommodation was elicited by stimulation of the Edinger-Westphal nucleus. Stimulus
amplitudes were chosen to produce accommodative response amplitudes of 1 D, 3 D
and 7 D. Four different stimulus shapes were used: either i) a single 4-second step,
or 4-second steps preceded by a pulse with an amplitude in µA of 150% of the step
amplitude and a duration of ii) 50 ms, iii) 100 ms and iv) 200 ms, respectively. The
amplitude of each stimulus pulse in µA was 150% of the amplitude of the following step.
Changes in lens thickness were recorded by dynamic ultrasound biometry at 100 Hz.
Dynamic A-scan lens thickness measurements were converted into accommodation
and the velocity and acceleration of the responses were determined using a two-point
difference algorithm.
Results: For each of the four stimulus shapes, there was a linear relationship of peak
velocity and peak acceleration of the accommodative response to the accommodative
amplitude. The slopes of the peak velocity versus amplitude regression lines increased
linearly with the duration of the pulse (y=0.0115x+1.8922, r²=0.99, p=0.005). The slopes
of the peak acceleration versus amplitude regressions were not influenced by the
pulse duration.
Conclusions: The results suggest that the relationship between peak velocity and
amplitude of Edinger-Westphal -stimulated accommodation in anesthetized rhesus
monkeys can be influenced in a systematic way using combined pulse-step stimuli.
CR: M. Baumeister, None; M. Wendt, None; C. Shooner, None; A. Glasser, None.
Support: NEI Grant #1 RO1 EY014651, DFG Grant BA 3443/1-1
4563 - A44
The Curvature Relations Between the Lens Surfaces and Measurements of Total
Rafractive Power, Radii of Principle Meridians on Ocular Anterior Segment
During Accommodation
E. Gambra, L. Sawides, S. Marcos. Instituto de Optica, Consejo Superior de
Investigaciones Cientificas, Madrid, Spain.
Purpose: Ocular aberrations are thought to play a role in accommodation (i.e.
larger lag in myopes associated to increased ocular aberrations or as cues to focus
direction). We studied the role of ocular aberrations on accommodation dynamics
(lag, fluctuations, aberration change and focus target tracking) by measuring optical
aberrations dynamically, with and without adaptive-optics (AO) correction.
Methods: Experiments were made with a fully-automatic custom AO system provided
with a Hartman-Shack wavefront sensor, an electromagnetic deformable mirror
(MIRAO, Imagine-Eyes), a motorized Badal system, a minidisplay for stimulus
presentation and pupil imaging channel. Aberrations were measured dynamically
(6.5 Hz) with natural and AO-corrected aberrations of the relaxed state. The pupil
dynamics was recorded simultaneously. Four conditions were tested: (1) Increased
accommodation demand (0-6 D) following a stair-case function (3 sec/step) (2) Off-On
(4 D) accommodation stimulus (3 cycles, 3 sec/condition) (3) Increased accommodation
demand (0-6 D) at 1.28 D/sec; (4) Decreased accommodation demand (6-0 D). Lag
was defined as residual defocus (including spherical aberration). Fluctuations were
estimated as the RMS standard deviationduring a 3 sec measurement. Five subjects
were tested (age: 26.6±4,0; refractive error: -0.2±0,5 D; accommodative range > 6 D
from IR dynamic retinoscopy).
Results: 1) In 4 eyes, the accommodative lag increased significantly (p<0.0002) with
AO correction (by 1.1±0.3 D on average). Lag decreased (by 0.2 D) with AO-correction
in the more aberrated eye. 2) Fluctuations of accommodation peaked at intermediate
demands both for natural (14.6±7.5% on average) and AO-correction (27.7±4.1% on
average). AO-correction decreased the fluctuation range in all eyes and conditions
(0.016±0.048 μm on average). 3) Spherical aberration decreased more consistently under
AO correction than in the natural condition (by 0.031±0.030 μm and 0.015±0.025 μm,
respectively on average, in the 0-6 D range). Coma showed systematic changes (both
for natural and AO-corrected conditions) within a subject, but the trends varied across
subjects. 4) All subjects followed the moving target without a significant delay and
showed a slight accommodative inertia when the target stopped moving.
Conclusions: Aberration dynamics are altered by correction of high order aberrations.
Fluctuations of accommodation are reduced when aberrations are corrected. Our lag
results indicate that while high amounts of aberrations may compromise accurate
fixation, a small amount of aberrations may provide accommodative cues
CR: E. Gambra, None; L. Sawides, None; S. Marcos, None.
Support: CSIC-I3P2006 Predoctoral fellowship to EG; MEyC FPI fellowship to LS.
MEyC FIS2005-04382 and EURYI Award to SM
Y. Chang1, H.-M. Wu2, Y.-F. Lin1. 1Inst of Biomedical Engineering, National YangMing University, Taipei, Taiwan; 2Radiology, Taipei Veterans General Hospital,
Taipei, Taiwan.
Purpose: To understand the relations between the radial change of the lens surfaces
during accommodation observed in 3D by using MRI technique.
Methods: MR imaging system equipped with ocular coil was used to acquire ocular
images in 6 healthy subjects with average age of 23.2 +/- 1.1 years. In our previous report
lens tilt and decentration as well as shape change on the ocular anterior segment by
accommodative stimuli of 60 (F), 40 (M) and 20 (N) cm were demonstrated. One month
later, retest was carried out in 5 of the 6 subjects as longitudinal study. Relations in
radial changes on both lens surfaces, sectional radii of the principle meridians and
total ocular refractive power were measured.
Results: Differences in total ocular refractive power change for F→M, M→N and
F→N are 0.79, 3.69, 4.48 D and 0.62, 2.75, 3.33 D in test and retest, respectively. Radial
relations between lens anterior surface (y) and posterior surface (x) can be fitted
by a simple equation y = -5.27-13271.12 *Exp(-x) with R(sqr) = 0.7995 and significant
difference of p = 0.027 in statistical means. In most of cases, statistical tests indicate no
significant difference (p < 0.05) is revealed in radial change between accommodative
demands for horizontal and vertical meridians, or between the two meridians at the
same demands in test and retest.
Conclusions: The 3D MRI technique allows the relations between the components
of ocular anterior segment to be simultaneously observed during accommodation.
In addition to commonly being noted changes in radius and refractive power, the
relations between the two lens surfaces during accommodation is linked and can be
fitted by a simple equation with high correlation coefficient.
CR: Y. Chang, None; H. Wu, None; Y. Lin, None.
Support: NSC90-2213-E-010-019 of the National Science Council, Taiwan, Republic
of China.
4560-4563
4564 - A45
Flattening of the Non-Human Primate Crystalline Lens Surfaces During
Simulated Accommodation
4565 - A46
Visual Suppression During Ocular Accommodation Is Velocity Dependent
D. Borja1,2, S. Uhlhorn1, K. Ehrmann 3,4, A. De Castro5, E. Arrieta-Quintero1, A.
Amelinckx1, D. Nankivil1,2, A. Ho3,4, F. Manns1,2, J.-M. Parel1,3. 1Ophthalmic Biophysics
Center, Bascom Palmer Eye Institute, Univ of Miami Miller School of Medicine,
Miami, FL; 2Department of Biomedical Engineering, Biomedical Optics and Laser
Laboratory, University of Miami, Coral Gables, FL; 3Vision Cooperative Research
Centre, Sydney, Australia; 4Institute for Eye Research, Sydney, Australia; 5Consejo
Superior de Investigaciones Científicas, Instituto de Optica, ‘‘Daza de Valde´s’’,
Madrid, Spain.
Purpose: To measure the changes in lens surface curvature during simulated
accommodation.
Methods: Accommodation simulation experiments were performed on 4 cynomolgus (2-6
years old) monkey and 2 baboon (3 years old) crystalline lenses within 3 hrs postmortem.
Tissue sections (lens, capsule, zonules, ciliary body, and sclera) were mounted in a 2nd
generation lens stretching system (EVAS II, Ehrmann et al, SPIE Proceedings Vol 5314)
and radially stretched in a stepwise fashion from the accommodated (zero load) to the
unaccommodated state. Lens cross-sectional profile was imaged at every step increment
with a custom designed OCT system. Image processing was performed to determine
lens thickness, anterior and posterior radii of curvature and asphericities from the OCT
images taken at every step increment.
Results: Radial stretching of the sclera by 3mm decreased lens thickness by 1.0±0.2mm and
1.2±0.2mm in the cynomolgus and the baboon lenses respectively. Lens diameter increased
by 1.0±0.4mm and 1.2±0.2mm in the cynomolgus and the baboon lenses respectively. Over
the central 6mm zone, the anterior radius of curvature increased on average by 7.4±0.3mm
and 6.5±1.4mm in the cynomolgus and baboon lenses respectively. The posterior radius
of curvature increased by 1.9±0.3mm and 1.4±0.1mm in the cynomolgus and baboon
lenses respectively.
Conclusions: Radial stretching forces produce a flattening of both anterior and posterior
surface curvatures in pre-presbyopic monkey lenses, as predicted by the Helmholtz
theory of accommodation.
Support: NIH Grants: 2R01EY14225, 5F31EY15395, P30EY14801 (Center Grant); NSF
Graduate Student Fellowship; I3P-CSIC Predoctoral Fellowship (De Castro); the Florida
Lions Eye Bank; an unrestricted grant from Research to Prevent Blindness; The Australian
Government CRC Scheme via Vision CRC, Sydney, Australia; the Henri and Flore Lesieur
Foundation.
CR: D. Borja, None; S. Uhlhorn, None; K. Ehrmann, None; A. De Castro, None; E.
Arrieta-Quintero, None; A. Amelinckx, None; D. Nankivil, None; A. Ho, None; F.
Manns, None; J. Parel, None.
Support: 2R01EY14225, 5F31EY15395 (Borja), P30EY14801 (Center Grant); Florida Lions
Eye Bank; RPB; Vision Cooperative Research; Henri and Flore Lesieur Foundation
N.C. Strang, S. Mucke, V. Manahilov, D. Seidel, L.S. Gray. Vision Science, Glasgow
Caledonian University, Glasgow, United Kingdom.
Purpose: Previously we have shown the presence of non-optical visual suppression
for high spatial frequencies during large (>2D) accommodation step responses. This
supports the suggestion that large accommodation step responses are pre-programmed
and do not require the negative feedback information which operates during steadystate and small step responses. As slow ramp changes in accommodation response
are also thought to be dependent upon negative feedback we would predict that
visual suppression would be absent for slower velocity large step responses. In this
study, we assess the extent of visual suppression present during accommodation
responses of varying velocity.
Methods: 5 young emmetropic subjects participated with informed consent in the
study. Contrast thresholds were measured using a 2-alternative forced-choice staircase
procedure during static and dynamic accommodation responses. Sinusoidal (1, 4, and 9
cpd) gratings were presented on a monitor at 1m for a duration of 26ms. In the dynamic
condition a 2 dioptre (1-3D) far to near accommodation stimulus was presented at
velocities of 0.5, 2, 3 and 10D/s while contrast threshold measurements were obtained
at pre-determined time points after stimulus onset. Contrast thresholds were also
obtained during steady state accommodation responses to 5 stimulus distances
ranging from 1m-33cm. Dynamic accommodation responses to the accommodation
stimulus were recorded by a modified infrared, open field autorefractor (Shin-Nippon
SRW-5000).
Results: Significant elevation (mean difference = 0.33 ± 0.12 log units, p<0.05) in
contrast thresholds for 9cpd were found during the fastest accommodation responses
(10D/s and 3D/s) in comparison to the static condition. This contrast threshold elevation
was found only at time points during the accommodation response. No elevation of
contrast thresholds was found for the slowest accommodation response velocities
(0.5 and 2 D/s) There were no significant elevations of contrast threshold for 1 and 4
cpd at any accommodation response velocities.
Conclusions: Non-optical visual suppression is present during fast accommodation
responses but is not found for slow responses. The results support the suggestion
that for large amplitude accommodation step responses there is an initial fast preprogrammed component followed by a small slow component which relies upon
continuous negative feedback about the degree of blur in the retinal image.
CR: N.C. Strang, None; S. Mucke, None; V. Manahilov, None; D. Seidel, None; L.S.
Gray, None.
Support: None
4566 - A47
The Relationship Between Accommodation Microfluctuations and Dynamic
Accommodation Step Responses
4567 - A48
Behavioral Accommodation Measured in Strabismic Monkeys With Infrared
Photorefraction
L.S. Gray, M. Day, N.C. Strang, D. Seidel. Vision Sciences, Glasgow Caledonian
University, Glasgow, United Kingdom.
H.M. Bossong1, M.H. Swann1, A. Glasser2, V.E. Das3,1. 1Sensory-Motor Systems, Yerkes
National Primate Research Center, Atlanta, GA; 2College of Optometry, University
of Houston, Houston, TX; 3Dept of Neurology, Emory University, Atlanta, GA.
Purpose: To investigate the influence of microfluctuations of accommodation upon
the characteristics of the dynamic accommodation step response.
Methods: 20 subjects (10 emmetropes and 10 myopes) participated with informed
consent in the experiment. The mean age of the subjects was 23.2±2.6 years and the
mean spherical refractive error ranged from -4.00DS to +0.50DS. Cylindrical correction
was ≤0.75DC and VA was ≤0.0 logMAR or better in all subjects. Subjects viewed
sinusoidal gratings (0.5, 4 and 16 c/deg) in a Badal optical system at vergence levels
of 1D and 4D achieved using a beamsplitter. Dynamic accommodation recordings
were made with a modified Shin-Nippon SRW-5000 infrared autorefractor. Subjects
made 10 accommodation step responses in each direction and mean step response
characteristics were calculated. Accommodation microfluctuations were obtained
from 2 minute recordings of the static accommodation response to the 1D target and
an average rms calculated.
Results: In all subjects, the rms of the accommodation microfluctuations was smallest
for the 4 c/deg grating and was significantly larger for both the 0.5 c/deg (p<0.01) and
the 16 c/deg (p<0.01) gratings. The rms was significantly greater (p<0.01) in the myopic
group at all spatial frequencies. The rms was significantly positively correlated with
the accommodation step response latency (r=0.38, p<0.01). The rms was significantly
negatively correlated with accommodation step response amplitude (r=-0.43, p<0.01)
and also significantly negatively correlated with accommodation step response
duration (r=-0.40. p<0.01).
Conclusions: Increases in the magnitude of the accommodation microfluctuations
are correlated with reductions in the quality of accommodation step responses. The
relationship between microfluctuations and step response dynamics is consistent
with the negative feedback model of accommodation response control. These findings
suggest that the accommodation microfluctuations are intrinsically related to the dead
space component in accommodation response control.
CR: L.S. Gray, None; M. Day, None; N.C. Strang, None; D. Seidel, None.
Support: None
Purpose: 1) To establish remote infrared photorefraction as a method for measuring
accommodation in awake behaving strabismic monkeys. 2) To examine issues
of photorefractor calibration specific to strabismic monkeys such as day to day
variability in calibration coefficients and calibration errors due to misalignment of
the photorefractor and the center of the pupil.
Methods: Data were collected from one normal and two strabismic juvenile rhesus
monkeys in 15 sessions. A remote infrared photorefractor, mounted on a camera placed
at a distance of 40cm, was aligned with the center of the pupil of an eye which was
occluded using an infrared-pass visible block filter. Photorefraction calibration was
performed by placing ophthalmic lenses (-2D to 5.5D) in front of the occluded eye
while the fellow eye fixated a 2°X2° Maltese cross at 60cm. To analyze calibration errors
due to misalignment between the photorefractor Purkinje image and the center of the
pupil, calibrations were performed as the animal fixated the target that was placed
at an eccentricity of 10° or 20° along the horizontal or vertical meridian. Analysis of
the video images was performed offline in MATLAB to convert slopes of the pupil
luminance profile to dioptric values.
Results: Calibration curves were generated from the ophthalmic lenses of known
power. Linear range of calibration usually extended from -1D to +4D. Calibration
coefficients obtained on 5 experimental days for each monkey showed small standard
deviations (straight-ahead target; slopes: N1-0.91+0.18; S1-0.67+0.14; S2-0.90+0.27)
increasing confidence in the repeatability of accommodation measurements.
Calibration coefficients obtained during 10° eccentric fixation, i.e., misalignment of
10° between photorefractor Purkinje image and center of pupil, was not significantly
different from the 0° (straight-ahead) fixation condition (10° slopes: N1-1.02+0.10;
S1-0.63+0.13; S2-0.77+0.27). Calibration coefficients obtained during 20° eccentric
fixation were also similar to the other conditions tested, but the standard deviation
of the slopes tended to be larger.
Conclusions: The infrared photorefraction technique can be reliably used to measure
accommodation in awake behaving normal and strabismic monkeys. Photorefractor
calibration is generally unaffected for small misalignment between the photorefractor
camera and the pupil center increasing the practicality of its use in strabismic
monkeys.
CR: H.M. Bossong, None; M.H. Swann, None; A. Glasser, None; V.E. Das, None.
Support: NIH Grant EY015312; Yerkes Base Grant RR00165
4564-4567
4568 - A49
The Effect of Blur Adaptation on the Dynamic Accommodation Responses of
Emmetropes and Myopes
E. Mallen, M. Cufflin. Division of Optometry, University of Bradford, Bradford,
United Kingdom.
Purpose: Adaptation to defocus is known to influence the subjective sensitivity to
blur in both emmetropes and myopes. Blur is a major contributing factor in the closedloop dynamic accommodation response. Previous investigations have examined the
static accommodation response following blur adaptation. Therefore, we investigated
whether a period of blur adaptation influences the dynamic accommodation response
to step and sinusoidal changes in target vergence.
Methods: Eighteen subjects (6 emmetropes, 6 early onset myopes and 6 late onset
myopes) underwent 30 minutes of adaptation to plano (control), +1 D or +3 D myopic
defocus whilst viewing a television picture. Following this adaptation period,
accommodation responses to a 2 D step change and 2 D sinusoidal change (0.2 Hz)
in target vergence were recorded continuously using a Shin Nippon SRW-5000 at a
sampling frequency of 22 Hz.
Results: Adaptation to defocus failed to influence accommodation reaction times, but
did influence response times to an inward step change in target vergence. Adaptation
to both +1 and +3 D induced significant increases in accommodation response time.
Overall mean response times increased from 0.66 ± 0.16 s at 0 D adaptation to 0.86
± 0.21 and 0.80 ± 0.16 s for +1 and +3 D adaptation respectively. Post hoc analysis
indicated that blur adaptation significantly increased the accommodation response
time in both the +1 DS and +3 DS adaptation conditions, although the difference
between these two adapting levels was not significant (Bonferroni; 0 DS vs +1 DS
p = 0.002, 0 DS vs +3 DS p = 0.012, +1 DS vs +3 DS p = 0.850). Blur adaptation also
significantly increased the peak-to-peak phase lag for accommodation responses to
a sinusoidally oscillating target. Overall mean phase lags increased from 27.94 ± 9.14
deg for 0 D adaptation up to 40.25 ± 16.42 deg and 46.87 ± 16.99 deg for +1 and +3 D
adaptation respectively. These changes in accommodative function were equivalent
across all refractive groups. Blur adaptation failed to have a significant effect on
accommodation microfluctuations.
Conclusions: Adaptation to a degraded stimulus causes an increased level of
accommodation for dynamic targets moving towards an observer and increases
response times and phase lags. An equivalent effect was found in both emmetropes
and myopes. It is suggested that the contrast constancy theory may explain these
changes in dynamic behaviour.
CR: E. Mallen, None; M. Cufflin, None.
Support: None
4568
Thursday, May 1, 8:30 AM - 10:15 AM Hall B/C Poster Session Program Number/Board # Range: 5269-5282 / A552-A565
520. Multifocal, Aspheric and Accommodating IOLs Organizing Section: VI
5269 - A552
Evaluation of Aspheric Intraocular Lenses Using Images of the CCD Camera of
the Model Eye With Variable Spherical Aberration
K. Ohnuma1, K. Negishi2, T. Yamaguchi2, T. Noda 3. 1Medical System Course, Chiba
University, Chiba-shi, Japan; 2Ophthalmology, Keio University School of Medicine,
Tokyo, Japan; 3Ophthalmology, National Hospital Organization Tokyo Medical
Center, Tokyo, Japan.
Purpose: To produce a model eye with variable spherical aberration to estimate the
effect of the aspheric surface on retinal images.
Methods: Using the model eye comprised of a camera lens and the CCD camera,
an IOL was put in a water cell, and the retinal images of the aspheric IOLs (FY60AD
[Hoya] and SN60WF [Alcon]) and spherical IOLs (YA 60BBR [Hoya] and SN60AT
[Alcon]) with a 5-mm aperture were captured with the CCD camera. The image
contrast of the optotypes at 0.5, and 1, 2, 3, 4, and 5 meters were compared. To add
corneal spherical aberration to the model eye, a phase plate of spherical aberration
was put between the camera lens with no spherical aberration. Three phase plates
with spherical aberrations of 0.16, 0.2, and 0.27 micrometer (6-mm diameter) were
tested to determine the effect of the spherical aberration. The green filter for color
separation was used to remove the affect of chromatic aberration. The FY60AD and
SN60WF were designed to compensate for 0.16 and 0.2 micrometer of corneal spherical
aberration respectively.
Results: The images of the two aspheric IOLs had high contrast when compensating for
0.16 micrometer of spherical aberration. With more than 0.27 micrometer of synthetic
spherical aberration, the contrast of the retinal images of the spherical IOLs decreased;
however, the depth of field was wider.
Conclusions: The effect of aspherical IOLs to compensate for corneal spherical
aberration could be visualized and evaluated objectively using the new eye model
camera.
CR: K. Ohnuma, None; K. Negishi, None; T. Yamaguchi, None; T. Noda, None.
Support: None
5270 - A553
Customized Aspherical Intraocular Lenses Calculated With Real Ray Tracing
J. Einighammer, T. Oltrup, T. Bende, B. Jean. Div Exp Ophth Sur, Centre for
Ophthalmology, Tuebingen, Germany.
Purpose: To calculate spherical, aspherical, toric and toric aspherical intraocular
lenses (IOLs) for pseudophakic eyes and simulate the potential benefit regarding the
wavefront error (WFE) by real ray tracing (RRT).
Methods: 45 pseudophakic eyes were evaluated. The anterior corneal surface was
measured with an OphthaTOP (OphthaSWISS AG) topography system; the posterior
surface was approximated from the anterior (both spline interpolated). The anterior
chamber depth was estimated. Axial length was measured with an IOLMaster
(Carl Zeiss Meditec AG). The geometry of customized spherical, aspherical, toric
and toric aspherical IOLs was calculated in an optimization process with RRT to
provide minimal root mean square (RMS) WFE. This was done for a “model eye”
constructed from the average patient data using an aspherical cornea with no higher
order aberrations (HOAs) besides spherical aberration (SA) as well as for each patient
including individual corneal topography (“real eyes”). Residual WFE was approximated
by Zernike polynomials according to the OSA standard and compared for the different
types of IOLs. All calculations refer to 6mm pupil diameter.
Results: Residual WFE for the model eye with spherical / aspherical / toric / toric
aspherical IOL: lower order aberration (LOA) RMS 0.81 / 0.81 / 0.00 / 0.00 µm, HOA
RMS 0.23 / 0.04 / 0.23 / 0.01 µm, SA RMS 0.23 / 0.04 / 0.23 / 0.00 µm. For the real
eyes (mean±SD): LOA RMS 0.83±0.86 / 0.83±0.86 / 0.08±0.16 / 0.07±0.13 µm, HOA
RMS 0.47±0.24 / 0.44±0.25 / 0.47±0.24 / 0.43±0.25 µm, SA RMS 0.17±0.10 / 0.09±0.10 /
0.17±0.10 / 0.07±0.07 µm. The toric aspherical IOL reduces the SA in both, model eye
and real eyes. In the model eye, HOAs are therefore reduced to almost zero; in real
eyes the reduction of HOAs is 8.5% compared to the toric IOL.
Conclusions: RRT has been used to calculate the exact geometry of customized
aspherical IOLs for providing the smallest possible WFE. For a model eye with no
HOAs besides SA it is possible to completely eliminate HOAs. For real eyes the SA is
significantly reduced - and therefore also the HOAs. However, the potential benefit
is somewhat limited, as the reduction of HOAs was below 10%. This prediction of
our theoretical calculations corresponds to several clinical investigations providing
wavefront measurements of pseudophakic eyes with spherical and aspherical IOLs.
CR: J. Einighammer, None; T. Oltrup, None; T. Bende, None; B. Jean, None.
Support: None
5271 - A554
On and Off-axis Optical Performance of Diffractive and Zonal Refractive
Intraocular Lenses
5272 - A555
Through-Focus Measurement of the Optical Transfer Functions of Diffractive
and Zonal Refractive Intraocular Lenses
J. Choi1A, J. Schwiegerling1B. ACollege of Optical Sciences, BOphthalmology & Vision
Science, 1University of Arizona, Tucson, AZ.
J. Schwiegerling1A, J. Choi1B. AOphthalmology, BOptical Sciences, 1University of
Arizona, Tucson, AZ.
Purpose: To compare the magnitude of stray light effects caused by various multifocal
intraocular lenses.
Methods: An artificial eye has been fabricated that has the average spherical and
chromatic aberration found in the human eye. This model eye contains a salinefilled wet cell into which various IOLs can be mounted. We captured images of a
negative USAF resolution target and 18 degree off-axis pinhole meant to simulate a
car headlight. We explored the performance of the Alcon ReSTOR, Tecnis ZM900 and
Acri.LISA diffractive multifocals, the AMO ReZoom zonal refractive multifocal and
the Eyeonics Crystalens accommodating IOL. To simulate dark conditions, the study
was done with maximum pupil allowed by the physical size of each IOLs.
Results: For the off-axis pinhole image, the ZM900 and the ReZoom showed more
flares around the image of the pinhole that were twice and 3 times, respectively, the
size of stray light features found with the ReSTOR and ReSTOR aspheric IOLs. Onaxis USAF target showed more stray light artifacts for the full-aperture diffractive
and zonal refractive IOLs compared to the apodized refractive lens.
Conclusions: Compared to other multifocal designs, aspheric apodized diffractive
IOL reduces stray light artifacts for both on- and off-axis lighting under large pupil
conditions.
Purpose: To measure the optical performance of various multifocal intraocular lenses
(IOLs) for different object vergences.
Methods: We fabricated an artificial eye with clinical levels of spherical and chromatic
aberration. The model contains a saline-filled wet cell into which various IOLs can be
mounted. A narrow slit was imaged through the eye model and captured with a CCD
array. The resultant line spread function was Fourier transformed to calculate the
Modulation Transfer Function (MTF). A Badal lens is used to create different object
vergences. In this manner, we can examine through-focus optical performance of
various IOLs. Three diffractive multifocal IOLs (Alcon ReSTOR aspheric, AMO Tecnis
ZM900, Acri.Tec Acri.LISA), as well as the AMO ReZoom zonal refractive multifocal
were measured. To simulate different lighting conditions, the study was done with
3 and 6 mm pupil sizes. Object vergences from 0 to -5 diopters were explored in 0.25
diopter steps. The MTF was evaluated at 15 cyc/deg for each of these positions.
Results: For the three diffractive lenses, the performance is similar for the 3 mm
pupil. For small pupils, the modulation is nearly evenly split between the distance
and near vision, with the Acri.LISA biased slightly to distance vision. The ReZoom
lens has higher modulation for distance vision, but negligible performance for near
vision the 3mm pupil. For 6 mm pupils, both the ReZoom and ZM900 have equally
split performance between distance and near vision. The Acri.LISA performance
remains slightly biased to distance vision and the ReSTOR aspheric dramtically
enhances distance performance.
Conclusions: The MTFs of these lenes illustrate different design philosophies for
multifocal lenses. The ReZoom provides almost no benefit to near vision for bright
lighting conditions due to a limited number of refractive rings falling over the pupil.
For larger pupil sizes, the performance with the ReZoom is split between distance
and near vision. Both the ZM900 and the Acri.LISA are full aperture diffractive
lenses meaning the near and distance performance remains constant for different
pupil sizes. The ZM900 equally splits the performance between distance and near
vision, while the Acri.LISA is slightly biased to distance vision. The ReSTOR aspheric
is an apodized diffractive transitioning from a pure diffractive under small pupils
to a diffractive/refractive structure for large pupils. The effect of the apodization is
to equally split performance between distance and near vision for small pupils and
dramatically enhance distance performance for large pupils.
CR: J. Schwiegerling, Alcon Laboratories, F; J. Choi, Alcon Laboratories, F.
Support: Research to Prevent Blindness
CR: J. Choi, Alcon Laboratories, F; J. Schwiegerling, Alcon Laboratories, F.
Support: Research To Prevent Blindness
5269-5272
5273 - A556
Optical Quality Performance Inside the Human Eye of Monofocal and
Multifocal Intraocular Lenses
5274 - A557
Test Images Acquired Through Three Multifocal Intraocular Lenses at Various
Object Distances
J.L. Alio1A, D. Ortiz1B, L. Bataille1B, G. Bernabeu1A. ARefractive Surgery, BR&D, 1Inst
Oftalmologico Alicante, Alicante, Spain.
D. Compertore1, L. Costanza2, I. Cox1. 1Optical Metrology, Bausch & Lomb, Rochester,
NY; 2Institute of Optics, University of Rochester, Rochester, NY.
Purpose: To study the optical performance of different intraocular lenses (IOLs) inside
the human eye in order to ascertain the influence of multifocality’s technology and
its relation with the pupil size.
Methods: The study included 30 eyes (10 eyes for each type: monofocal Acrysof,
multifocal diffractive ReSTOR and multifocal refractive Rezoom). The intraocular
optical quality was characterized for 3 and 5 mm pupils by means of the difference
between total and corneal aberrations measured three months after surgery. When
making the subtraction, both maps were referred to the pupil center and the conditions
of illumination are the same for both measures. Our software allows to introduce the
off-set between maps in order to introduce a realignment algorithm in the calculations
of the difference. The main outcomes measures were intraocular aberrations (RMS
value), Modulation Transfer Function (MTF) values, Point Spread Function (PSF)
and Strehl ratio.
Results: The refractive multifocal Rezoom showed higher intraocular aberrations than
the diffractive ReSTOR and standard monofocal (p = 0.022) (Figure 1. Comparative
maps of the intraocular wavefront of the 3 IOLs for 3 mm (Top) and 5 mm (Center)
pupil diameters. Bottom: E-Snellen simulation considering the total ocular aberrations
for 5 mm pupil diameter). The difference in spherical aberration between ReSTOR
and Rezoom were statistically significant for 5 mm (p = 0.003) and for 3 mm pupil
(p = 0.001). There were no statistically significant differences for coma aberration
between IOLs (p = 0.185) for 3 mm, and, for 5 mm pupil, the ReSTOR showed the
lower values (p = 0.012).
Conclusions: Multifocal refractive intraocular lens showed higher intraocular
aberrations. The increase of optical aberrations when the pupil is enlarged from 3 to
5 mm was compensated by the hybrid design of the refractive-diffractive IOL.
Purpose: The aim of this study is to: (1) present for evaluation retinal images taken
through three commercially available intraocular lenses (IOL’s), and (2) experimentally
measure the add power of each IOL.
Methods: The AcrySof™ ReSTOR™, ReZoom™ and Tecnis™ multifocal IOL’s were
tested on an optical imaging bench with a new 43D model eye. Images of a USAF
1951 target were taken through each IOL at object distances ranging from infinity
to 286 mm. For each lens, the CCD camera was first focused at infinity. The object
was then moved closer to the lens until the best near focus was achieved. Finally the
add-power for each lens was estimated.
Results: The published add power of the AcrySof™ ReSTOR™, ReZoom™ and Tecnis™
multifocal IOL’s is 4.0D, 3.5D and 4.0D, respectively. As tested through the new 43D
model eye the measured add power of the AcrySof™ ReSTOR™, ReZoom™ and
Tecnis™ multifocal IOL’s is 2.5D, 2.25D and 2.5D, respectively. All lenses show the
typical primary focused image at infinity and the secondary image with a near
object, without any physical refocusing of the CCD camera. The difference between
the published add- powers and the measured add-powers is due to interaction of the
IOL power with the corneal power.
Conclusion: Accounting for the interaction with the cornea, all three IOL’s test as
having their prescribed add-power. The USAF target images gathered during this
test provides a library of images which can be used to make subjective decisions as to
which lens provides better retinal image quality for distance and near vision.
CR: D. Compertore, Bausch and Lomb, E; L. Costanza, Bausch and Lomb, C; I. Cox,
Bausch and Lomb, E.
Support: None
CR: J.L. Alio, None; D. Ortiz, None; L. Bataille, None; G. Bernabeu, None.
Support: None
5275 - A558
Predicted Optical Performance of Pseudophakic Eyes Corrected for Spherical
and Chromatic Aberrations Through an Intraocular Lens
5276 - A559
Comparison of Wavefront Aberrations in Eyes With Implantation of an
Aspheric IOL or a Spherical IOL
H.A. Weeber1, P. Artal2, P. Piers1. 1Research & Development, AMO Groningen,
Groningen, The Netherlands; 2Laboratorio de Optica, Universidad de Murcia,
Murcia, Spain.
I.G. Cox1A, K.H. Edwards1B, R. Sun1B. ALens Eye Research, BClinical Affairs, 1Bausch &
Lomb, Rochester, NY.
Purpose: To use clinically verified eye models to explore depth of focus (DOF), sensitivity
to intraocular lens (IOL) tilt and decentration in pseudophakic eyes corrected for spherical
and chromatic aberrations.
Methods: White light pseudophakic eye models were constructed from the measurements
of 46 cataract patients. Models were verified using the average measured contrast sensitivity
function (CSF) and wavefront aberration of pseudophakic patients implanted with two
types of IOL. Separately, longitudinal spherical aberration (LSA)- and longitudinal
chromatic aberration (LCA)- correcting IOLs of different powers were optimized in
an eye model with the LSA and LCA of the average aphakic eye. The IOLs, which had
aspheric anterior surfaces and diffractive posterior surfaces, were fitted in the 46 eye
models. DOF, and sensitivity to IOL decentration and IOL tilt were evaluated based on
modulation transfer function (MTF). The results were compared with standard spherical
and aspherical IOL results.
Results: When comparing spherical and aspherical lenses, the improvement in the
physiological eye models correlated well with the improvement in clinical outcomes.
When only LSA was corrected (aspheric IOLs) the improvement was ~20% over
pseudophakic eyes without correction (spherical IOLs). When both LSA and LCA were
corrected, improvement over pseudophakic eyes with no correction was ~50%. The DOF
of IOLs that corrected for LSA and LCA was similar to the DOF of spherical and aspherical
IOLs (Figure). Lenses that corrected for LSA and LCA could be, on average, decentered
by as much as 0.8 mm before their polychromatic MTF at 8 cpd was less than that of the
aspheric or spherical control lenses. The lenses are relatively insensitive to lens tilt.
Conclusions: Realistic eye models that include higher order aberrations and chromatic
aberration are important in determining the impact of new IOL designs. The results of
this study indicate that the improvement obtained with IOLs that aim for the complete
correction of LSA and LCA is clinically significant without sacrificing DOF.
Purpose: The objective of this study was to compare wavefront aberration measured
in eyes with spherical or aspheric IOLs.
Methods: This was a prospective, randomized and multi-center study. A total of 54
subjects received either an aspheric IOL (SofPort AO) or a spherical IOL (AcrySof
SA60AT) during cataract surgery from 5 study sites. Wavefront aberration was
measured at 3 and 6 months after surgery using the Bausch & Lomb Zywave (I/II)
waveFront aberrometer. Prior to data analysis, pupil sizes were standardized at 3mm,
4mm and 5mm. The results were compared statistically between the spherical lens
eyes and aspheric lens eyes.
Results: At 3 months postoperatively, mean spherical aberration was 0.02um; 0.07um;
0.18um at 3mm, 4mm and 5mm pupils respectively in the aspheric lens eyes. In the
spherical lens eyes, mean spherical aberration was 0.04um; 0.12um; 0.30um at 3mm,
4mm and 5mm pupils respectively. The differences between the aspheric lens eyes
and spherical lens eyes were statistically significant at all the pupil sizes (p<0.001). At
6 months postoperatively, mean Spherical Aberration was 0.02um; 0.06um; 0.12um at
3mm, 4mm and 5 mm pupils individually in aspheric lens eyes comparing to 0.04um;
0.11um; 0.28um at 3mm, 4mm and 5mm pupils individually in spherical lens eyes.
Again, the differences were statistically significant at all pupil sizes (p<0.001).
Conclusions: The results of this study have confirmed that spherical aberration was
significantly reduced in eyes with an aspheric IOL implantation compared to eyes
that received a spherical IOL.
CR: I.G. Cox, Bausch & Lomb, E; K.H. Edwards, Bausch & Lomb, E; R. Sun, Bausch
& Lomb, E.
Support: None
CR: H.A. Weeber, AMO, E; P. Artal, AMO, C; P. Piers, AMO, E.
Support: None
5273-5276
5277 - A560
Two-Year Performance of the Tetraflex KH3500 ‘Accommodative’ Intraocular
Lens
5278 - A561
Development of a Ciliary Muscle Driven Accommodative IOL
J.S. Wolffsohn1, L.N. Davies1, N. Gupta1, S.A. Naroo1, G.A. Gibson1, S. Shah2,1.
1
Optometry, Aston University, Birmingham, United Kingdom; 2Midland Eye
Institute, Birmingham, United Kingdom.
Purpose: To determine the two year performance of eyes implanted with the Tetraflex
(Lenstec, Kellen KH-3500) ‘accommodative’ intraocular lens (IOL).
Methods: Thirty-seven patients who had been implanted with the Tetraflex
‘accommodating’ IOL at least two years previously, 19 binocularly, were assessed.
Outcome measures were refraction, visual acuity, contrast sensitivity, subjective and
objective amplitude-of-accommodation, aberrometry and capsule opacification.
Results: The average time since implantation of the Tetraflex lens was 2.64 ± 0.32 years.
Best-corrected distance acuity was +0.04 ± 0.24 logMAR, contrast sensitivity +1.35 ±
0.21 log units and best distance-corrected near acuity was 0.61 ± 0.17 logMAR. The
subjective amplitude-of-accommodation was 1.53 ± 0.64 D, subjective range-of-clearfocus 0.77 ± 0.29 D and objective amplitude-of-accommodation was 0.21 ± 0.19 D. The
magnitude of higher order aberrations was 0.96 ± 1.26 microns through 4 mm pupils.
Twenty-three eyes (48%) had already received or were waiting for a YAG capsulotomy.
Binocular implantation resulted in improved contrast sensitivity and best distancecorrected near visual acuity than the monocularly viewing better eye (p<0.001). The
improvement in binocular over monocular subjective amplitude-of-accommodation
was predictable from the monocular measurement (p<0.001).
Conclusions: The Tetraflex ‘accommodating’ IOL maintains a small objective
accommodating effect and reasonable subjective focusing range over two years
post-implantation, although posterior capsular opacification was common.
CR: J.S. Wolffsohn, Lenstec, F; Lenstec, C; L.N. Davies, Lenstec, F; N. Gupta, None;
S.A. Naroo, Lenstec, F; G.A. Gibson, None; S. Shah, Lenstec, F; Lenstec, C.
Support: None
G.L. Van der Heijde1, E.A. Hermans1, T.T. Terwee2, S.A. Koopmans3, M. Dubbelman1,
R.M. Heethaar1. 1Dept. Physics and Medical Technology (FMT), VU University
Medical Center, Amsterdam, The Netherlands; 2AMO Groningen BV, Goningen,
The Netherlands; 3Ophthalmology, University Medical Center Goningen,
Goningen, The Netherlands.
Purpose: To design a ciliary muscle driven accommodative IOL that has a
predictable and large range of variable power. The optical quality at different states
of accommodation should be comparable to that achieved with a monofocal IOL.
Methods: A concept IOL (“Turtle lens”) has been designed with a new focus
mechanism that could operate within the dynamics of the ciliary muscle. The new
focus mechanism contains two freeform lenses that move perpendicular to the optical
axis. The Turtle lens has a base power of 21 D and accommodative amplitude of 8 D.
The concept design was optically and mechanically optimized for a typical 60-yearold human eye. Silicon prototypes were made to test mechanical performance in pig
and human donor eyes using a laboratory lens stretching device that mimics the
ciliary muscle action. Changes in focal length during stretching were measured by
laser-based ray tracing and a camera system.
Results: During stretch experiments the focal length of the Turtle lens changed
according to the design for 8 D of accommodation. Theoretical ray tracing showed that
the modulation transfer function (MTF) of the Turtle lens in different accommodative
states did not deviate considerably from the MTF of a monofocal IOL. However, the
optical quality of initial prototypes was affected due to deformation of the silicon
lenses during the stretch experiments.
Conclusions: In stretch experiments of pig and human cadaver eyes, the results of base
power and accommodation were in accordance with the functional design. Therefore,
the new focus principle can be used in the development of an IOL that restores
accommodation. Both the mechanical and optical design need further optimization
to improve optical quality and functionality.
CR: G.L. Van der Heijde, None; E.A. Hermans, None; T.T. Terwee, Employee, E; S.A.
Koopmans, None; M. Dubbelman, None; R.M. Heethaar, None.
Support: Supported by the SenterNovem grant IS043081 and Advanced Medical
Optics (AMO Groningen B.V.)
5279 - A562
Reading Speed With Synchrony Dual Optic Accommodating IOL. One and Two
Year Results
5280 - A563
Visual Outcomes and Patient Satisfaction of Cataract and Refractive
Lensectomy Patients Receiving Bilateral ReZoom Multifocal Implants
L.G. Vargas1, G. Lau1, S. Kasthurirangan1, R. Alarcon2, V.M. Bohorquez2. 1Visiogen,
Irvine, CA; 2Department of Ophthalmology, Cataract and Refractive Surgery,
Servioftalmos, Bogota, Colombia.
R.E. Evans, F.A. Bucci, Jr.. Bucci Laser Vision Institute, Wilkes Barre, PA.
Purpose: Accommodating intraocular lenses are a promising technology for the
correction of pseudophakic presbyopia. In order to succeed, these lenses should
provide functional near vision sustainable over time. To assess this, we evaluated
reading speed at 1 year and 2 years in patients implanted bilaterally with the Synchrony
dual optic IOL.
Methods: Prospective, non comparative series of cases. A high contrast reading speed
chart in Spanish was developed based on the MNRead chart. Font, size and style
were maintained, and the same structure of sentences with 60 characters divided
into 3 text lines and 10 standard (3rd grade level) words per sentence were used. All
measurements were obtained at 40 cm. Distance corrected near visual acuity (DCNVA)
and reading speeds without near add were evaluated in nineteen bilateral Synchrony
patients at 10.12 months (1 year) and 22.13 months (2 years) average follow-up visit.
Reading speeds were measured at 1.0 to best achievable logRAD acuity to calculate
threshold reading acuity, critical print size (CPS), reading speed at 0.4 logRAD and
maximum reading speed.
Results: Four patients could not read 150 words/ minute (wpm) at any font size either
at the 1 year or 2 year intervals and were excluded from statistical analysis. A 2-way
ANOVA showed a significant effect of print size (p<0.05) and year of testing (2 year
better than 1 year; p < 0.05), while the interaction effect was not significant (p = 0.14).
DCNVA was linearly correlated with threshold reading acuity at both 1 year (r2: 0.70,
p < 0.05) and 2 years (r2: 0.60, p < 0.05). DCNVA was not different between 1 and 2
years (0.09 vs. 0.05 logMAR; paired t-test, p = 0.35). Reading acuity was significantly
better at 2 years (0.07 logRAD) than at 1 year (0.11 logRAD) (paired t-test, p < 0.05).
There was no statistical difference in reading speed at 0.4 logRAD (newspaper print
size) between 1 year (mean ± SD: 180.5 ± 61wpm) and 2 years (mean ± SD: 184.2 ± 42
wpm). Overall, functional near vision measures were stable from 1 to 2 years.
Conclusions: This study demonstrates the long term performance of the Synchrony
accommodating IOL in providing excellent distance corrected near vision and reading
ability.
CR: L.G. Vargas, Visiogen Inc, E; G. Lau, Visiogen Inc, E; S. Kasthurirangan, Visiogen
Inc, E; R. Alarcon, Visiogen Inc, R; V.M. Bohorquez, Visiogen Inc, R.
Support: None
Purpose: To evaluate the visual outcomes and patient satisfaction of cataract (KPE) and
refractive lensectomy (RL) pts. receiving bilateral ReZoom (RZ) IOLs when excluding
patients with mesopic pupils < 4.0mm and who expressed an extreme need to achieve
fine detailed near vision.
Methods: A retrospective, single center review of 71 pts. (142 eyes) who received
bilateral RZ IOLs was completed. 49 females (69%) and 22 males (31%) underwent
78 KPEs (55%) and 64 RLs (45%). The mean age was 57 yrs. (27 to 87). Visual and
refractive outcomes were assessed including UCVA, BCVA, unilateral near and
intermediate VAsc, bilateral near and intermediate VAsc, spherical equivalent (SE),
and astigmatism. Patients were asked if they would repeat the same course of surgery,
and rates of spectacle independence were assessed. Surgery was performed on the
dominant eye first with a target refraction of plano to -0.12. If after 2-3 wks. pts. were
satisfied with their near vision, the same (pl to -0.12) refractive outcome was targeted
in the nondominant eye. If the pt. sought stronger near vision, -0.50 was targeted in
the nondominant eye. Patients with mesopic pupils < 4.0mm and those having an
extreme need for fine detailed near vision were excluded.
Results: 142 eyes had a mean preop VAsc of 20/285 (20/20 to 20/4000). Mean preop
BCVA was 20/27 (20/15 to 20/400) and the mean preop SE was -1.06 (-15.87 to +6.62).
Preop refractive cylinder was 0.91D. The mean postop VAsc was 20/24, (KPE: 20/25- /
RL: 20/22) after all Yags (45%) and refractive surgeries for residual refractive error (33%
),12 LASIK, 2 PRK and 23 microRK/AK were completed. The mean SE and refractive
astigmatism postop were -0.22D and 0.37D respectively. The mean bilateral near
vision (best focal point) was J1.32 (J1.79 unilateral). The mean bilateral intermediate
vision (arm’s length) was J1.88 (J2.79 unilateral). At near bilaterally, 80% (RL) and 75%
(KPE) were J1, 95% (RL) and 87% (KPE) were > J2, and 99% (RL) and 97% (KPE) were
> J3. At intermediate bilaterally, 80% (RL) and 75% (KPE) were > J2, and 95% (RL) and
86% (KPE) were > J3. Mean follow up was 43 wks (11-96). Eighty-four percent of pts.
claimed they never use glasses, and 67 patients (94.4%) said they would have this same
surgery again. No pts. received or discussed having an explantation.
Conclusions: High levels of pt. satisfaction were achieved with bilateral RZ resulting
from 1) proper pt. selection, 2) aggressive correction of residual refractive error, and
3) an effective combination of functional uncorrected near and intermediate vision
(RL: 80% J1 at near & 80% > J2 at intermediate / KPE: 75% J1 at near & 75% > J2 at
intermediate).
CR: R.E. Evans, None; F.A. Bucci, None.
Support: None
5277-5280
5281 - A564
Laboratory Evaluation of Nighttime Halos for Multifocal IOLs
5282 - A565
Reasons for Patient Dissatisfaction After Multifocal Intraocular Lens
Implantation
M.J. Simpson, D.R. Carson, F. Zhou, X. Hong, X. Zhang, M. Karakelle. Surgical IOL
Research, Alcon, Fort Worth, TX.
Purpose: To evaluate the nighttime halos of multifocal intraocular lenses (IOLs) in
the laboratory.
Methods: Nighttime halos are caused by defocused light that is directed to the second
image of a multifocal IOL. The characteristics of the defocused light energy were
evaluated in the laboratory using a model eye for several multifocal IOL designs. A
5 mm illuminated lens diameter was used to simulate typical conditions of nighttime
vision in a pseudophakic eye. Direct measurement of the line spread function (LSF),
which is the intensity across the image of a bright slit object, was found to provide an
objective method for evaluating the defocused light energy. Quantitative measurements
of the defocused halo intensity and size were made from LSF plots recorded using
monochromatic light for several different lens designs. The LSF is the integral across
the point spread function (PSF), which is the image of a point source. The LSF has the
property of amplifying the intensity of the defocused halo of the PSF, which makes the
measurement robust when evaluating the extremely faint halo of the ReSTOR Aspheric
IOL. Images of the PSF were also recorded, using a pinhole to simulate a distant light
source at night, with the same system settings for the different lenses so that a direct
visual comparison can be made of the nighttime optical properties.
Results: LSF measurements and pinhole images demonstrated that the ReSTOR
Aspheric apodized diffractive multifocal intraocular lens, which directs most of
the incident light to the distance focus under large pupil conditions at night, has a
minimal defocused image component. These results were compared to those from a
full-aperture equal-energy constant step height diffractive IOL (AMO Tecnis), and a
5-zone refractive IOL (AMO ReZoom). The laboratory results agree with clinical data,
where the incidence of nighttime visual disturbances is low for ReSTOR IOLs.
Conclusions: Measurement of the LSF in a laboratory model eye can be used to
quantitatively measure the nighttime halos for multifocal IOLs, and laboratory
images of a pinhole source can be used for comparative evaluations of different
IOL designs.
CR: M.J. Simpson, Alcon, E; D.R. Carson, Alcon, E; F. Zhou, Alcon, E; X. Hong,
Alcon, E; X. Zhang, Alcon, E; M. Karakelle, Alcon, E.
Support: None
M.A. Woodward, J.B. Randleman, R.D. Stulting. Ophthalmology, Emory University
Eye Center, Atlanta, GA.
Purpose: To analyze outcomes and reasons for dissatisfaction in eyes after
phacoemulsification with multifocal intraocular lens implantation.
Methods: Retrospective review of 52 eyes from 38 patients dissatisfied with visual
outcomes after multifocal lens implantation. Outcomes analyzed included type of
visual complaint, nature of treatment modality for each complaint, and presence or
absence of clinical improvement.
Results: Patients complaints could be characterized as blurred vision resulting
from ametropia, post-operative complications [cystoid macular edema, dry eye, lens
decentration, posterior capsular opacification (PCO)], photic phenomena [glare, halos,
dysphotopsias], or a combination of both. Blurred vision occurred in 47 (91%) eyes
resulting from ametropia in 21 (45%)eyes, post-operative complications such as dry
eye and cystoid macular edema in 8 eyes, lens decentration in 6 (13%) eyes, and early
PCO in 23 (49%) eyes. Photic phenomenon occurred in 16 (30%) eyes resulting from
intrinsic lens properties in 5 (31%) eyes, lens decentration in 5 (31%) eyes, retained
lens fragment in 1 (6%) eye, and PCO in 8 (50%) eyes. In 15 (27%) eyes, the etiology
of blurred vision and photic phenomenon was multifactorial. Blurry vision was
manifest as decreased near vision in 20 (38%) eyes, decreased distance vision in 11
(21%) eyes, and both in 16 (31%) eyes. Dissatisfied patients were identified by clinical
findings and treated accordingly. 23 (44%) of these patients experienced clinical
improvement with various treatment modalities including refractive surgery for 3
(13%) eyes, complication management for dry eye and for inflammation for 2 (9%) eyes,
brimonidine administration for photic phenomena in 2 (9%) eyes, YAG capsulotomy
for 15 (65%) eyes, and lens repositioning or lens exchange in 2 (9%) eyes. An additional
17 (33%) eyes were pending treatment results. 17 (74%) eyes required only 1 modality
of treatment, while 6 (26%) eyes required more than 1 treatment modality.
Conclusions: Patient dissatisfaction presents as blurry vision, photic phenomenon,
and frequently as a combination of both. Most patients can be successfully managed
and experience clinical improvement with one or more treatment modalities.
CR: M.A. Woodward, None; J.B. Randleman, None; R.D. Stulting, None.
Support: NIH Grant EYO6360
5261-5282
Thursday, May 1, 10:45 AM - 12:30 PM Palm A Paper Session Program Number Range: 5390-5396
526. Imaging Retinal Disease Organizing Section: VI Contributing Section: RE
5390 - 10:45AM
In vivo Imaging of Structural Changes in Foveal Sparing in Advanced Atrophic
AMD With Simultaneous cSLO and SD-OCT
5391 - 11:00AM
Structural Correlation Using Adaptive Optics Scanning Laser Ophthalmoscopy
in X-Linked Retinoschisis
S. Schmitz-Valckenberg1A, M. Fleckenstein2, H.-M. Helb1A, P. Charbal Issa1A, H. Scholl1A,
F.G. Holz1B. ADepartment of Ophthalmology, BOphthalmology, 1University of Bonn,
Bonn, Germany; 2Department of Ophthalmology, University of Bonn, Bonnn,
Germany.
J.L. Duncan1, Y. Zhang2, S.M. Sundquist1, A. Solovyev1, S. Chang1, N. Smaoui 3, A.
Roorda2. 1Ophthalmology, University of California, San Francisco, San Francisco,
CA; 2School of Optometry, University of California, Berkeley, Berkeley, CA;
3
National Eye Institute, Bethesda, MD.
Purpose: The fovea in patients with geographic atrophy (GA) secondary to AMD may be
spared until late in the course of the disease. Previously, we have characterized variations
in fundus autofluorescence (FAF) associated with GA. In this study, we investigated
morphological alterations of the fovea at various anatomical layers in presence of foveal
sparing using high resolution in-vivo imaging.
Methods: Simultaneous spectral domain optical coherence tomography (SD-OCT, 870 nm,
40.000 A-scans/sec) and confocal scanning laser ophthalmoscopy (cSLO; FAF, redfree,
and nearinfrared imaging mode) were performed in 11 GA patients (mean age 79 years,
range 68-100) with foveal sparing using a combined instrument (Spectralis HRA+OCT,
Heidelberg Engineering, Heidelberg, Germany). All patients had central fixation and
visual acuity of 20/40 or better. Anatomical layers were evaluated, and retinal thickness
in the central fovea and at the outer macula were measured and compared to agematched controls.
Results: Instead of the symmetric annulus of decreased intensities in normal subjects, FAF
imaging showed an irregular reduced signal at the residual foveal island in all patients.
SD-OCT scans revealed an overall increased retinal thickness with disappearance of the
foveal pit. An increased, irregular and broad band of reflectivity at the retinal pigment
epithelium and outer neurosensory retina was observed. Inner retinal layers appeared
to be distorted with tipping over towards perifoveal atrophy where marked retinal
thinning and absence of characteristic morphology of outer retinal layers were seen. The
mean retinal thickness in the central fovea was 229 µm compared to 189 µm in normals
(p = 0.003, Wilcoxon Signed Rank Test). No statistical difference of the thickness in the
retinal areas peripheral to the GA was noted (251 versus 262 µm; p = 0.6).
Conclusions: Combined cSLO and OCT high-resolution imaging allowed for visualization
of previously unknown and distinct structural foveal alterations despite well-preserved
central visual function. Thickening in absence of leakage and cystoid spaces may reflect
a preapoptotic stage of foveal neuronal cellular elements indicating incipient atrophy.
Longitudinal observations correlating function and morphology will be helpful to better
understand the dynamic process of developing foveal atrophy in patients with GA, as
well as monitoring future interventions aiming at slowing GA enlargement.
CR: S. Schmitz-Valckenberg, None; M. Fleckenstein, None; H. Helb, None; P. Charbal
Issa, None; H. Scholl, None; F.G. Holz, Heidelberg Engineering, Zeiss Meditec, F;
Heidelberg Engineering, Zeiss Meditec, C.
Support: DFG Ho 1926/1-3, Ho 1926/3-1 (SPP 1088)
Purpose: To study macular structure in a patient with X-linked retinoschisis (XLRS)
with high-resolution imaging.
Methods: Best-corrected visual acuity (VA), fundus examination, automated perimetry
and fundus-guided microperimetry, optical coherence tomography (OCT), fluorescein
angiography (FA) and full-field electroretinography (ERG) were obtained. Molecular
analysis of the RS1 gene was performed. Adaptive Optics Scanning Laser Ophthalmoscopy
(AOSLO) was used to generate high resolution montages of the macula.
Results: A 29 year old man with VA of 20/50 OD and 20/63 OS demonstrated foveal schisis
without leakage on FA and vitreous veils but no peripheral schisis cavities. Automated
and fundus-guided perimetry showed relative scotomas within 5 degrees of fixation.
OCT showed a large central cyst with schisis in the outer and inner plexiform layers.
The mixed scotopic ERG b-wave was reduced to a greater extent than the a-wave, with
a b/a ratio of 0.8. A hemizygous C duplication was present at nucleotide 579 in exon 6
(c.579dupC) in the RS1 gene. This mutation changed isoleucine to histidine at residue
194 (p.Ile194Hisfs) and is predicted to create a frameshift in the retinoschisin protein
adding 75 amino acids. The right eye was chosen for AOSLO imaging. Cones and foveal
schisis were readily observed across the 7 degree AOSLO image. The preferred retinal
locus was displaced 2.5 degrees temporal, at the edge of a large central cyst involving the
anatomic fovea. Within the cyst, cone spacing was increased (i.e., reduced cone density),
corresponding to a dense scotoma on fundus-guided microperimetry. Outside of the
large central cyst, cone spacing was similar to normal but visibility of the contiguous
mosaic was disrupted by the edges of the schisis cavities.
Conclusions: AOSLO imaging demonstrated foveal schisis and cone structure in a
patient with XLRS. Cone spacing was increased within a large cyst at the anatomic
fovea, but nearly normal beginning at 2.5 degrees eccentricity. This study presents the
first microscopic images of cones in a patient with a known mutation in the RS1 gene.
Such images should provide a sensitive measure of the effect of this mutation on cone
viability during the course of disease progression.
CR: J.L. Duncan, None; Y. Zhang, None; S.M. Sundquist, None; A. Solovyev, None; S.
Chang, None; N. Smaoui, None; A. Roorda, Optos PLC, C; University of Houston;
University of Rochester, P.
Support: NIH Grants EY00415, EY014375, Research to Prevent Blindness, Foundation
Fighting Blindness, The Bernard A. Newcomb Macular Degeneration Fund, That Man
May See, Inc.
5392 - 11:15AM
In vivo 3D Imaging of Age Related Macular Degeneration Using Optical
Coherence Tomography at 1050 Nm
5393 - 11:30AM
Imaging Polarimetry in Macular Disease
D.L. Burnes1, D.M. de Bruin1, J. Loewenstein2, Y. Chen1, S. Chang2, T. Chen2, D.D.
Esmaili2, J.F. de Boer1. 1Wellman Center for Photomedicine, Massachusetts General
Hospital, Harvard Medical School, Boston, MA; 2Massachusetts Eye and Ear
Infirmary, Harvard Medical School, Boston, MA.
Purpose: To assess the application of ophthalmic optical frequency domain imaging (OFDI) at
1050 nm, in combination with post-image processing methods, for the detection of type I choroidal
neovascularization (CNV) in patients with age related macular degeneration.
Methods: An OFDI system consisting of a swept laser with a bandwidth of 64nm centered
at 1050nm was developed. Patients were imaged before treatment with ranibizumab, and
subsequently imaged following 4-8 treatments. The 3D image sets were processed with an
anisotropic diffusion filter to reduce noise and enhance edge contrast. The subretinal fluid,
intra-retinal edema and CNV volumes were segmented using connected threshold and levelset semi-automated algorithms. Enface images from the OFDI cross sections were co-registered
with color fundus photography (CFP) and fluorescein angiography (FA), in addition to compiling
CNV thickness maps.
Results: In post treatment scans, the subretinal fluid and retinal edema volumes were dramatically
reduced if not completely absent, as well as a reduction in the CNV volume (see table). The CNV
thickness maps correlate to the areas corresponding to confirmed and suspected CNV on FA.
Conclusions: The detailed images of the retina and choroid allow for obtaining volumetric
measurements of abnormal structures characterizing AMD using post-image processing methods.
This technology may contribute to early non-invasive diagnosis of AMD, and potentially serve
as a valuable post-treatment monitoring tool.
Patient
Treatment
Patient 1
Patient 2
Patient 3
pre
post
pre
post
pre
post
Segmentation Volumes (mm3)
CNV
Subretinal fluid
0.231
0.965
0.125
0.00323
0.221
0.0641
0.0653
0
0.476
0
0.304
0
Intra-retinal edema
0
0
0.140
0
1.82
0
CR: D.L. Burnes, None; D.M. de Bruin, None; J. Loewenstein, None; Y. Chen, None; S. Chang,
None; T. Chen, None; D.D. Esmaili, None; J.F. de Boer, None.
M. Miura1, A.E. Elsner2, B.L. Petrig2, D.A. VanNasdale2, B.P. Haggerty2, T. Iwasaki 3.
1
Deptartment Ophthalmology, Tokyo Medical University, Kasumigaura Hospital,
Inashiki, Japan; 2School of Optometry, Indiana University, Bloomington, IN;
3
Deptartment Ophthalmology, Tokyo Medical University, Kasumigaura Hospital,
Inashiki, Japan.
Purpose: To evaluate the different features of the macular disease with polarimetry
images.
Methods: We prospectively examined cases with central serous chorioretinopathy,
epiretinal membrane, early cases of age related macular degeneration, Vogt-KoyanagiHarada disease, and malignant melanoma. Polarimetry images were digitized using
a GDx-N (Laser diagnostic technologies), with scanning polarized light at 780 nm.
We computed 18 different image types According to polarizeation content, to probe
different features of macular diseases. The image types were as follows: 1.Depolarized
light image, 2. Maximum of the crossed detector, 3. Birefringence image, 4. Ratio of
the crossed detector, 5. Minimum of the parallel detector, 6. Maximum of the parallel
detector, 7.Modulation of the parallel detector, 8. Ratio of the parallel detector, 9.
Mean Parallel Polarized, 10. Mean Modulation of the Crossed, 11. Average reflectance
image, 12. Ratio Depolarized [ 2 x min( crossed ) ] / [ Mean_Parallel_Polarized +
mean(crossed )], 13. Mean of the Crossed Polarizer, 14. Mean of the Parallel Polarizer,
15. mean( parallel ) - modulation( parallel ), 16. mean( crossed ) + mean( parallel ) mod( parallel ), 17. Phase retardation map 1(Crossed Detector Phase Plot), 18.Phase
retardation map (Parallel Detector Phase Plot)
Our new metric, the ratio depolarized light image, is designed to emphasize light
scatter due to structural changes, because it divides out the index of refraction changes
that cause more light return at a given location regardless of polarization content.
This is of particular interest in diseases with lesions deep to the retina that may be
masked by the overlying bright retinal layers.
Results: In both the depolarized light images and the ratio depolarized images, deeper
retinal lesions were particularly well-visualized. These results demonstrated the
interaction of light and tissue in patients with a new image type, the ratio depolarized
images, as well as in diseases with potential changes deep to the retina and not
studied previously with this type of technique: Vogt-Koyanagi-Harada and malignant
melanoma.
Conclusions: Polarization sensitive imaging is an effective tool as a non-invasive
assessment of macular disease.
CR: M. Miura, None; A.E. Elsner, None; B.L. Petrig, None; D.A. VanNasdale,
None; B.P. Haggerty, None; T. Iwasaki, None.
Support: NEI EY007624
5390-5393
Thursday, May 1, 10:45 AM - 12:30 PM Palm A Paper Session Program Number Range: 5390-5396
526. Imaging Retinal Disease Organizing Section: VI Contributing Section: RE
5394 - 11:45AM
Automatic Drusen Segmentation and Characterization in Spectral Domain
Optical Coherence Tomography (SDOCT) Images of AMD Eyes
5395 - 12:00PM
Detection of Retinal Disease by Cross-Correlation of Different Imaging Modes
C.A. Toth1A,1B, S. Farsiu1A, S.J. Chiu1B, A.A. Khanifar1A, J.A. Izatt1B,1A. AOphthalmology,
B
Biomedical Engineering, 1Duke University, Durham, NC.
Purpose: To search for imaging biomarkers of age-related macular degeneration (AMD)
progression. Accurate detection of drusen volume and characteristics is important as
drusen size and type predicts progression. In previous small-scale SDOCT studies, drusen
segmentation and characterization were done manually. In a large-scale multi-year study,
with hundreds of patients each with hundreds of scans, a manual approach is impractical.
Automatic image analysis is critical to expedite drusen analysis.
Methods: Eyes with Age-Related Eye Disease Study Level 3 AMD were imaged, with
SDOCT (Bioptigen, Inc. Durham, NC) to create 3D representations of the retina and drusen.
Initial automated segmentations of retinal nerve fiber layer followed by retinal pigment
epithelium (RPE) layer were further improved by using an iterative deformable snake,
which was later corrected for outliers. By fitting locally convex curves to this possibly
unhealthy RPE curve, the healthy shape of the RPE layer was estimated. Area between
estimated unhealthy and healthy RPE outlines was marked as drusen location. Individual
drusen characteristics (e.g. shape, internal reflectivity) previously only evaluated visually,
were mathematically defined and evaluated. All methods were implemented in a graphical
user interface software package based on MATLAB platform. Total drusen volume and
characteristics were measured for the central subfield by the automatic system and then
refined with grader-adjusted analysis (GAA).
Results: Using this software, resulting volume and characteristics of drusen produced nonoverlapping subcategories for eyes with Level 3 AMD. Although most drusen were detected
by the software resulting in GAA of less than 25% of volume (compared to interobserver
difference after GAA of ~7%); there was a consistent increase in drusen volume with GAA,
due to the ad-hoc definitions of the level of the outline defining the base of drusen areas.
Automated drusen volume measurement (6 sec per frame), even with GAA, was many times
faster than manual grading. Confluent drusen were frequently found by software and verified
on GAA in eyes with soft indistinct drusen.
Conclusions: The developed software accurately segments and categorizes drusen in
the SDOCT images of AMD eyes. Errors can be manually corrected using a user-friendly
software interface and the program is constantly refined to correct for the repeating errors.
This semi-supervised approach significantly reduces the time and resources needed to
conduct a large-scale AMD study.
CR: C.A. Toth, Bioptigen Inc., Sirion, Alcon Laboratories, Genentech, F; Alcon Laboratories,
P; S. Farsiu, Bioptigen Inc., F; S.J. Chiu, None; A.A. Khanifar, None; J.A. Izatt, Bioptigen
Inc., F; Bioptigen Inc., I; Bioptigen Inc., E; Bioptigen Inc., P.
Support: This research was funded by NIH R21EY017393 (JAI pi), SBIR grant 2R43EY018021-01
with subcontract from Bioptigen, and the North Carolina Biotechnology Center Collaborative
Funding Grant.
B.L. Petrig, A.E. Elsner, D.A. VanNasdale, B.P. Haggerty, Y. Zhao, S.A. Burns. School of
Optometry, Indiana University, Bloomington, IN.
Purpose: To test the hypothesis that in normal eyes, the well-ordered retinal layers
are relatively transparent and the light return is mainly specular, while in retinal
disease, the tissues become disordered and pathology leads to increased scattered
light. This implies that images of the deeper layers are less well correlated with those
of superficial layers in diseases such as age-related macular degeneration (AMD)
compared to normal eyes. We compared images obtained with different imaging
modes, e.g. specular light vs. multiply scattered light, which emphasize superficial
vs. deep retinal layers using cross-correlation techniques.
Methods: Sixteen patients, classified by clinical criteria to have early AMD, mean age
69 years, and 28 controls, mean age 68 years, were imaged using confocal scanning
laser ophthalmoscopy with near infrared illumination. The grayscale values of directly
backscattered light images and multiply scattered light images were compared by a
zero-lag cross-correlation algorithm. When derived from the same raw image data,
both computed image types are inherently aligned, and the zero-lag cross-correlation
coefficient was used. With two sequential data sets, images were first aligned using
one or more landmarks. The cross-correlation function was plotted in 3-D to assess
alignment accuracy and strength of correlation using peak value and peak width. The
distribution, mean and sources of variability of the cross-correlation were examined,
with the means compared by ANOVA.
Results: Multiply scattered light images appeared strikingly different from directly
backscattered light images for patients with AMD, but sometimes confined to focal
changes. The zero-lag cross-correlation coefficients of 14 deg regions overlapped
for AMD patients and controls, 0.54 to -0.02 and 0.72 to 0.12, respectively. The mean
coefficient was smaller, but not significantly so, for AMD vs. controls (0.35±0.13 vs.
0.43±0.18, p<0.15). The multiply scattered light images frequently enhanced drusen and
pigmentary changes in controls, potentially decreasing correlation coefficients.
Conclusions: Multiply scattered light images were never well-correlated with directly
backscattered light images in our older subjects. Drusen and pigmentary changes
may lead to poor correlation between directly backscattered and multiply scattered
light images.
CR: B.L. Petrig, None; A.E. Elsner, None; D.A. VanNasdale, None; B.P. Haggerty,
None; Y. Zhao, None; S.A. Burns, None.
Support: EY007624 (AEE), EB002346 (AEE), EY017886 (DAV)
5396 - 12:15PM
Spectral Domain Optical Coherence Tomography (SDOCT) Imaging in the
Spectrum of Pediatric Ocular Albinism
G.T. Chong1A, S. Farsiu1A, A.J. Korieshi1A, S.F. Freedman1A, C.A. Toth1B. AOphthalmology,
B
Ophthalmology, Biomedical Engineering, 1Duke University, Durham, NC.
Purpose: To evaluate the spectrum of foveal architecture using high-speed, highresolution SDOCT in pediatric ocular albinism. Because pediatric patient movement,
either due to nystagmus or shortened attention span, limits time domain OCT imaging,
SDOCT was used in this study.
Methods: SDOCT imaging was performed on both eyes of children in three groups:
OA) with foveal hypoplasia and nystagmus on clinical exam but lacking some classic
features of ocular albinism (5 subjects), OCA) with classic oculocutaneous albinism
(1 subject) and NL) age and ethnicity matched normals (4 subjects). Ten by ten mm
volumetric scans (containing 100 B-scans of 1000 A-scans each) were captured using
standard and handheld SDOCT systems (Bioptigen Inc., Research Triangle Park,
NC). The raw B-scan data were analyzed with ImageJ software (NIH; Bethesda,MD).
The B-scan data were registered, cropped, and the outlier scans removed prior to
data summation to yield a composite high-quality image of each subject’s fovea.
Images were scored for presence or absence and configuration of each retinal layer
across the fovea.
Results: Clinical exams of subjects showed: OA-- foveal hypoplasia, 20/40-20/60
acuity, nystagmus, light irides, and mild skin pigment; OCA-- foveal hypoplasia,
20/200 acuity, pale skin, and iris transillumination defects; NL-- 20/20 acuity and
no nystagmus. Due to multiple rapid scan acquisition, we were able to capture highquality images of all subjects, even those with notable nystagmus. Imaging revealed
a variable range of abnormalities in foveal architecture of all eyes with OCA and OA
when compared to NL. These included minor changes in the photoreceptor layer, high
reflectivity across the fovea suggesting persisting nerve fiber layer, and presence of
multiple inner retinal layers normally absent at the center of the fovea.
Conclusions: Rapid scanning capability of SDOCT allows more precise imaging even
when faced with nystagmus. Persisting inner retinal layers on SDOCT imaging of
OA and OCA defines the foveal hypoplasia seen clinically and could be the etiology
of reduced acuity. Our SDOCT findings suggest that ocular albinism may represent
a spectrum of foveal architectural changes. This imaging modality may be useful in
evaluating OA suspects at a young age.
CR: G.T. Chong, None; S. Farsiu, Bioptigen Inc., F; A.J. Korieshi, None; S.F. Freedman,
Pfizer, C; C.A. Toth, Bioptigen Inc., F; Sirion, F; Alcon Laboratories, F; Genentech, F;
Alcon Laboratories, P.
Support: None
5394-5396
Thursday, May 1, 10:45 AM - 12:30 PM Hall B/C Poster Session Program Number/Board # Range: 5638-5650 / A539-A551
541. Refractive Surgery Outcomes Organizing Section: VI
5638 - A539
Multizone Model for Postsurgical Corneas. Analysis of Standard and Custom
LASIK Outcomes
5639 - A540
Comparison of Corneal and Total Ocular High-Order Optical Aberrations
Before and After Myopic Laser in situ Keratomileusis
L.M. Gonzalez1, J.L. Hernandez-Matamoros1, R. Navarro2. 1Clinica Oftalmologica
RealVision, Madrid, Spain; 2ICMA, Consejo Superior de Investigaciones
Científicas-Universidad de Zaragoza, Zaragoza, Spain.
D. Gatinel, P. Adam, S. Chaabouni, J. Munck, M. Thévenot, T. Hoang-Xuan, H. Bains,
CEROC (Center of Expertise and Research in Opticsfor Clinicians). Ophthalmology,
Rothschild Foundation - AP-HP Bichat Claude Bernard, Paris, France.
Purpose: To develop a model of post-surgical corneas and its application to analyze
the outcomes of standard and custom myopic LASIK treatments.
Methods: The optical zone (OZ), transition zone (TZ) and periphery are segmented
automatically by a clustering algorithm. For each point, we compute three physical
magnitudes: Gauss curvature, root-mean-square (RMS) fit error, and distance to the
vertex, which are then used as local descriptors in the segmentation. Both pre-surgical
and post-LASIK corneal topographies were compared using monozone and multizone
models. Three groups of patients (31 eyes) were studied according to the treatments
applied: Allegretto (custom), Zyoptix (custom) and PlanoScan (standard).
Results: The multizone model improved the goodness of fit from 2.4 ± 0.7 to 1.2 ± 0.4
μm (post-LASIK). The segmentation permitted us to estimate the diameter, shape and
decentration of the different zones. The estimated central ablation (OZ) area was always
lower than nominal value (average diameter 6.6 ± 0.3 mm versus 5.5 ± 0.4 mm) and
showed elliptical shape (average e = 0.27). In the OZ, curvature radii increased after
surgery, and conic constants (-0.41) became positive (+0.29). No significant differences
were found between Zyoptix and PlanoScan: Corneal HOA increased by a factor of
2; for Allegretto HOA increased by 3.
Conclusions: The analysis of the three different LASIK treatments showed no
improvement of custom over standard treatments. The mutizone model shows a higher
fidelity representation of the corneal topography and permits a deeper understanding
of the post-surgical cornea.
CR: L.M. Gonzalez, None; J.L. Hernandez-Matamoros, None; R. Navarro, None.
Support: None
Purpose: To evaluate the changes in total and corneal aberrations and the
compensation of aberrations within the human eye after conventional myopic laser
in situ keratomileusis (LASIK).
Methods: Total and corneal aberrations were measured preoperatively and 3
months postoperatively for 57 eyes. The NIDEK EC-5000 excimer laser was used for
all treatments. Total and corneal aberrations root-mean-square (RMS) values were
calculated out to the 6th Zernike orders for a 6.0-mm pupil diameter. The percentage
of increase after surgery was defined by the ratio between the RMS values preand postoperatively for each of the corneal and total eye aberration groups. The
compensation between corneal and internal aberrations for a given aberration group
was defined by the ratio:(corneal aberration group RMS- total eye aberration group
RMS)/ corneal aberration group RMS). A p-value less than 0.05 was considered
statistically significant.
Results: Postoperatively, higher order aberrations showed a statistically significant
increase after myopic LASIK by a factor of 1.77±1.26 (total) and 2.47±2.25 (corneal) (p
<0.05). Coma aberration increased by 2.43±2.61 (total) and 2.56±2.66 (corneal) . Spherical
aberration increased by a factor 1.46±1.83 (total) and 2.64±2.24 (cornea). The values
of the ratio of compensation did not show statistically significant differences before
and after LASIK for individual aberrations (p>0.05).
Conclusions: Although myopic LASIK induced significant corneal aberrations, the
level of partial compensation of corneal aberrations by internal structures remained
unchanged. These results may suggest that a previously described emmetropization
that is effective not only with developmental factors but also with acquired variations
in corneal shape.
CR: D. Gatinel, None; P. Adam, None; S. Chaabouni, None; J. Munck, None; M.
Thévenot, None; T. Hoang-Xuan, None; H. Bains, None.
Support: None
5640 - A541
Early Refractive Outcomes of Wave-Front Guided Sub-Bowman’s
Keratomileusis (SBK) With 110µm and 90µm Femtosecond Flaps
5641 - A542
Visual and Clinical Outcomes of Wavefront Guided Myopic Lasik With Iris
Registration
K.A. Kerns1, B.H. Jeng1, R.R. Kruger1, A.S. Roth1, W.J. Dupps, Jr.1,2. 1Cole Eye Institute,
Cleveland, OH; 2Department of Biomedical Engineering, Lerner Research Institute,
Cleveland Clinic, Cleveland, OH.
O. Muftuoglu, P. Prasher, M. DiPascuale, V.V. Mootha, S. Verity, W.L. Bowman, D.H.
Cavanagh, J.P. McCulley. Ophthalmology, UT Southwestern Medical School, Dallas, TX.
Purpose: To compare the refractive outcomes of thin-flap LASIK with 90µm and
110µm femtosecond flaps to determine if surgeons need to account for their choice of
flap thickness in the treatment offset.
Methods: We performed a retrospective, IRB-approved chart review of 178 consecutive
patients who had CustomCornea LASIK for myopia (Alcon LADARVision 6000) with
femtosecond flaps (Intralase fs 60) performed by two surgeons (RK and WD). Eyes with
3-5 month follow-up were divided into 2 groups: 88 eyes with 90µm flaps and 90 eyes
with 110µm flaps. Preoperative and surgical variables in each group were compared
using student t-test with a p value < .05 indicating significance.
Results: Preoperative central corneal thickness (CCT) differed between in the 90µm
(543±22µm) and 110µm groups (557±33µm, p=0.002), while attempted correction,
simulated keratometry and patient age did not (p>0.09). Surgeon offsets differed
between the 90µm (+0.34±0.28D) and 110µm groups (+0.12±0.30D, p<0.001). Regression
analysis demonstrated no correlation between postoperative spherical equivalent
(SE) refractive error and CCT. Visual acuity outcomes were no different in the 2
groups. Actual postoperative SE was no different between the 90µm (-0.09±0.39D)
and 110µm (-0.10±0.36D) groups (p=0.9) but differed slightly after adjustment for the
offset (p=0.1). Intended and measured flap thickness (by intraoperative subtractive
pachymetry) were poor predictors of adjusted SE refractive error in single predictor
and multivariate analyses, and surgeon offset only explained a small portion of the
variance in refractive outcome (R 2=4.8%, p=0.003).
Conclusions: The choice of a 90µm vs.110µm femtosecond flap had no measurable
effect on early refractive outomces in custom myopia treatments.Though surgeons
tended to treat thinner corneas with 90µm flaps and apply slightly larger positive
SE offsets in this group, intended flap thickness nevere demonstrated significance
as a predictor of refractive outcome. Offset adjustments on the basis of intended flap
thickness in the 90-110µm range do not appear to be necessary.
CR: K.A. Kerns, None; B.H. Jeng, None; R.R. Kruger, Alcon & IntraLase consultant
and travel funds, F; A.S. Roth, None; W.J. Dupps, None.
Support: Research to Prevent Blindness, NIH grant 1KL2RR024990 (BHJ and WJD)
Purpose: To evaluate the visual and clinical outcomes of wavefront-guided laser in
situ keratomileusis (LASIK) with iris registration platform (VISX CustomVue, VISX
Inc., Santa Clara, CA) in myopic correction.
Methods: Forty-two eyes of 23 patients were enrolled in a prospective multisurgeon
clinical outcome study. Uncorrected visual acuity (UCVA), best spectacle-corrected
visual acuity (BSCVA), and manifest refraction were measured at 1 day, 1 week, 1
month, and 3 months postoperatively. Contrast sensitivity with and without glare
was measured at 1 month and 3 months, and higher-order aberrations (HOAs) were
measured at 3 months postoperatively.
Results: Mean preoperative spherical equivalent (SE) was reduced from -3.28 ± 2.2 D
(range: -0.75 to -9.5 D) to a SE of -0.11 ± 0.28 D (range: 0 to -1.25) at 1 month and -0.12
± 0.22 D (range: +0.25 to -0.75 D) at 3 months (P < 0.001). Ninety-five percent of eyes
at 1 month and 92.9% of eyes at 3 months were within ± 0.5 D of emmetropia. At 1
and 3 months, UCVA was 20/20 or better in 76.2.3% and 80.9%, respectively. No eye
lost more than 1 line of BSCVA. Compared to preoperative levels, the mean contrast
sensitivity with and without glare increased in all spatial frequencies at 3 months
postoperatively. The mean total higher-order aberrations increased from 0.45 ± 0.14
µm preoperatively to 0.52 ± 0.27 µm at 3 months postoperatively without statistical
significance (P = 0.144).
Conclusions: A wavefront-guided LASIK platform with iris registration is safe,
effective, and delivers excellent visual results for the correction of low to moderate
myopia.
CR: O. Muftuoglu, None; P. Prasher, None; M. DiPascuale, None; V.V. Mootha,
None; S. Verity, None; W.L. Bowman, None; D.H. Cavanagh, None; J.P. McCulley,
None.
Support: Research to prevent blindness
5638-5641
5642 - A543
Contralateral Comparison of WASCA versus Iris Recognition Guided WASCA
Using MEL80 Excimer Laser System
5643 - A544
Impact on Vision of the Lasik Surgery Depending on the Patients’ Optical
Quality
F. Wu, Y. Yang. Ophthalmology, the second Hospital Affiliated to Zhejiang
University, Hangzhou, China.
J. Pujol1A, A. Padilla1A, M. Vilaseca1A, J.C. Ondategui1B, M. Arjona1A, F. Sanabria1A, J.L.
Guell2, D. Elies2. ACD6-Optica i Optometria, BCUV-Optica i Optometria, 1Universitat
Politecnica Catalunya, Terrassa, Spain; 2Cornea-Refractive Surgery Unit, IMO,
Barcelona, Spain.
Purpose:To verify whether there is any difference in visual outcome after performing
WASCA (wavefront supported corneal ablation) and iris recognition guided WASCA
(IR-WASCA) of the same patient 3 month after surgery.
Methods: This was a prospective randomized study of 104 myopic eyes (52 patients)
that had LASIK using the MEL80 excimer laser system. IR-WASCA was used in
the first eye of the patient (study group) and the other eye of the same patient was
operated with WASCA surgery (control group). Mean refractive error was similar
between left and right eyes of the same patient. Higher order aberration(HOAs),
Contrast sensitivity function(CSF), UCVA and BCVA were recorded preoperative
and 1-month, 3-month postoperative. Corneal topographic maps were performed
preoperative and 3-month postoperative.
Results: The mean cyclorotation of IR-WASCA group was -2.0+/-4.2 degree(rang
-11.2~7.9 degree). At 3 month after surgery, UCVA was 20/20 or better in 96.2% of
IR-WASCA group and 90.3% of WASCA group. A significant difference in CSF was
found between the two groups at 2.5, 1.6, 1.0 degree.
Conclusions:IR-WASCA provides a better quality of vision as they detect and
compensate cyclorotation to give a more precise ablation profile.
CR: F. Wu, None; Y. Yang, None.
Support: None
5644 - A545
Contrast Sensitivity and Wavefront Analysis After Custom LASIK vs. Custom
PRK
J. Barreto, Jr., M.V. Netto, A. Reis, M. Ruiz Alves, S.J. Bechara. University of Sao Paulo,
Sao Paulo, Brazil.
Purpose: To compare contrast sensitivity and wavefront analysis after wavefrontguided LASIK (WFG-LASIK) in one eye and wavefront-guided PRK (WFG-PRK) in
the fellow eye for myopia and myopic astigmatism correction.
Methods: A prospective study of 70 eyes (35 patients) submitted to simultaneous
WFG-LASIK and WFG-PRK (contra-lateral eye). High and low contrast visual acuity,
wavefront analysis (high-order aberrations, Strehl ratio, modulation transfer function)
and contrast sensitivity were performed preoperatively and at one, three and six
months postoperatively. Spatial contrast sensitivity was performed for 20 eyes.
Results: In the WFG-LASIK group, 60% eyes had UCVA > or = 20/16 and 94.3% >
or = 20/20, and in the WFG-PRK group, 54% and 94.3%, respectively. The mean pretreatment total high-order aberrations (total HOA) was 0.334+/-0.07μm in the WFGLASIK group and 0.359+/-0.11μm in the WFG-PRK group (P= .594). At six months,
the mean total HOA was +0.455+/-0.13D and -0.441+/-0.15D, respectively (P= .688).
Contrast sensitivity has improved similarly for both groups.
Conclusions: RMS values of total HOA and other terms showed no statistically
significant difference between custom LASIK and custom PRK. Contrast sensitivity
has improved after wavefront-guided ablations without significant difference between
LASIK and PRK. Both techniques were effective in correcting low myopia and myopic
astigmatism with good high and low contrast visual acuity.
CR: J. Barreto, None; M.V. Netto, None; A. Reis, None; M. Ruiz Alves, None; S.J.
Bechara, None.
Support: None
Purpose: To evaluate and compare the relative impact on the vision quality caused by
LASIK surgery, in patients with different optical quality at the pre-surgical stage.
Methods: In this study we evaluate the changes in the eye’s optical quality after
LASIK surgery, taking into account the results reported for several groups of patients
with different optical qualities at the pre-surgical stage. We analyze relative the
improvement or worsening in the visual quality that take place in those different
groups considered.The eye’s optical quality is measured by means of the double-pass
system OQAS (Optical Quality Analysis System, Visiometrics), which provides the
OQAS VALUE (OV), parameter that accounts for the visual quality of the patients.
Specifically, its standard values range from 0 to 2 approximately. Values higher
than 1 are related to an acceptable visual quality.25 LASIK myopic patients were
included in this study. Their eye’s optical quality was analyzed by means of the
OQAS VALUE and the Visual Acuity (BSCVA, best spectacle corrected visual acuity,
and UCVA, uncorrected visual acuity), at the pre-surgical stage and one month after
the intervention. Only patients with a preoperative BSCVA of 20/25 or better were
included in the comparison.
The following groups of patients’ eyes with different optical quality ranges (presurgical) were considered: 5 eyes corresponding to patients with OV<0.6, 11 with
0.6<OV<0.9, 16 with 0.9<OV<1.2 and 11 with OV higher than 1.2.
Results: The results obtained show that patients with a poor optical quality before the
surgery have a relative improvement of their visual quality after the LASIK surgery
with respect to their initial quality. Specifically, an averaged improvement in the
OQAS VALUE of 29% (patients with OV<0.6) and 17% (patients with 0.6<OV<0.9) is
observed. However, in the other two groups a very different behavior is shown after
the surgery; in patients with 0.9<OV<1.2, a mean worsening of 5% in the optical quality
is found. In patients with OV higher than 1.2, the patients show a worsening in the
visual quality of approximately 37%.
Conclusions: The higher the optical quality is at the pre-surgical stage, the larger
is the worsening shown in terms of optical quality in LASIK patients. This effect
could explain the patient complains after LASIK, mainly if they have a good vision
before the surgery.
CR: J. Pujol, None; A. Padilla, None; M. Vilaseca, None; J.C. Ondategui, None; M.
Arjona, None; F. Sanabria, None; J.L. Guell, None; D. Elies, None.
Support: Grant DPI2005-08999-C02-01 Ministerio de Educación y Ciencia - SPAIN
5645 - A546
Maximum Disparity After Lasik
J.J. Castro, J.R. Jiménez, E. Hita, R.G. Anera. Optics, University of Granada, Granada,
Spain.
Purpose: To evaluate stereoscopic vision after LASIK and the role of post-surgical
interocular differences in higher-order eye aberrations, corneal asphericity, and
initial anisometropia.
Methods: We measured maximum disparity with a mirror stereoscope pre-(bestcorrected) and after LASIK for 30 patients. Their mean pre-operative spherical
refractive error was -4.7±2.0 D, ranging from -1.0 to -8.0 D. Data on aberrometry were
taken with a WASCA aberrometer. Corneal shape data were provided by a corneal
topographer. For each patient, the anisometropia was computed as the difference
between the spherical equivalent of each eye.
Results: The results showed that stereoscopic vision is less effective after LASIK, since
for 93% of the patients, maximum disparity diminished. This lower maximum disparity
implies a reduction in the physical region where stereoscopic perception occurs
and thus in the quality of stereopsis. We also found that the larger the interoculardifferences in post-surgical corneal asphericity the less effective the stereopsis (r=0.82,
p<0.01); on the other hand, the greater the differences in the higher-order aberrations,
the worse the quality of stereoscopic vision (r=0.85, p<0.01). Analyzing pre-LASIK
anisometropia we found that maximum disparity diminishes for increasing values
of initial anisometropia (r=0.87, p<0.01).
Conclusions: Our results indicate that stereopsis deteriorates after LASIK. Ablation
algorithms should minimize interocular-differences (aberrations and corneal
aasphericity) to avoid a decrease in binocular visual performance.
CR: J.J. Castro, None; J.R. Jiménez, None; E. Hita, None; R.G. Anera, None.
Support: Ministerio de Educación y Ciencia (Spain) grant FIS2006-01369 and Junta
de Andalucía (Spain) grant P06-FQM-01359
5642-5645
5646 - A547
Long-Term Results of the Artisan Phakic IOL for the Correction of Severe and
Extreme Hyperopia in the United States: A Prospective Multi-Center Study
R.U. Desai, A. Jain, E.E. Manche, Artisan Hyperopia Lens Study Group.
Ophthalmology, Stanford School of Medicine, Stanford, CA.
Purpose: Our study describes the results of a Phase III United States FDA investigation
on the Artisan phakic intraocular lens (PIOL) for the correction of hyperopia up to +12.0
D. The endpoints focused on refraction efficacy, predictability, stability, and safety.
Methods: The Artisan hyperopic PIOL is fabricated from ultraviolet-absorbing
polymethylmethacrylate. It was implanted in 95 eyes of 60 subjects at 13 participating
trial sites located throughout the United States. Inclusion criteria included endothelial
cell counts (ECC) of at least 2000 cells/mm 2 and anterior chamber depth (ACD) of at
least 3.2 mm. The goal of all surgeries was emmetropia. 46 eyes were followed for
3 years.
Results: Implant diopter strength averaged 7.55 ± 2.04 D (range +4.0 to +12.0 D). Preoperative ACD averaged 3.40 ± 0.17 mm. The pre-operative mean spherical equivalent
(MSE) averaged +5.47 ± 1.45 D, while the third post-operative year MSE averaged
-0.56 ± 0.65 D. By this third post-operative year, 65.5% of eyes were within ± 0.5 D and
98.2% were within ± 1.0 D of the intended correction. Pre-operative best corrected
visual acuity (BCVA) was 20/20 or better for 75.8% of eyes and 20/40 or better for all
of eyes, while at the third post-operative year, 21.4% of eyes achieved uncorrected
visual acuity (UCVA) of 20/20 or better, and 85.5% of eyes achieved 20/40 or better.
By the third post-operative year, 72.7% of eyes achieved a BCVA of 20/20 or better
with all eyes achieving a BCVA of 20/40 or better. ECC decreased by 4.3% over three
years from 2588 to 2400 cell/mm 2 (p < 0.01).
Conclusions: The Artisan PIOL provides effective and predictable correction of
hyperopia up to +12.0 D.
5647 - A548
Alterations in Higher-Order Aberrations Following Cataract Surgery
G. Mishor1, G.F. Schmid2, T. Lifshitz3, J. Levy3, S. Rosen4, J.M. Wild1. 1Cardiff
School of Optometry and Vision Sciences, Cardiff University, Cardiff, United
Kingdom; 2Pennsylvania College of Optometry, Philadelphia, PA; 3Department
of Ophthalmology, Soroka Medical Center, Ben-Gurion University of the Negev,
Beer-Sheva, Israel; 4Center for Multidisciplinary Research in Aging, Ben-Gurion
University of the Negev, Beer-Sheva, Israel.
Purpose: To determine the changes in higher-order aberrations (HOA) following
cataract surgery.
Methods: The cohort comprised 39 eyes from 39 patients (mean age 73.1, SD 7.7) who
had undergone cataract extraction by phacoemulsification and intra-ocular lens
implantation. Eight HOAs (Total, TiltS1, High, TComa, TTrefoil, T4foil, TSph and
HiAstg) were measured using the NIDEK Optical Path Difference Scanning System
ARK-10000 aberrometer prior to surgery (Mean 3.5 weeks, SD 2.0), approximately 10
weeks post operatively (Mean 10.7 weeks, SD 7.6) (PO1) and approximately 18 months
post-operatively (Mean 18.6 months, SD 3.5) (PO2). The root mean square (RMS) values
for each HOA were separately compared over the three time periods.
Results: Following cataract extraction and IOL implantation, the group mean RMS
values for most HOAs progressively decreased in magnitude at PO1 and at PO2.
However, the reductions in magnitude only reached statistical significance at PO1 for
Total (p<0.001), Tilt (p=0.002), and High (p=0.039) and additionally at PO2 for T3foil
(p=0.007), and TSph (p=0.004). The differences in magnitude between PO1 and PO2
did not reach statistical significance.
Conclusions: As would be expected, cataract extraction and IOL implantation resulted
in an improvement in most aberrations at PO1 and this improvement was maintained at
PO2. However, Tcoma and Hi-Astig remained unchanged and would therefore appear
to be largely independent of the crystalline lens. This latter finding has implications
for the design of future IOLs.
CR: G. Mishor, None; G.F. Schmid, None; T. Lifshitz, None; J. Levy, None; S. Rosen,
None; J.M. Wild, None.
Support: None
CR: R.U. Desai, None; A. Jain, None; E.E. Manche, is a stock holder of Calhoun
Vision, I; received some travel support from VISX, AMO, and Intralase, R.
Support: Ophtec
5648 - A549
The Effect of Nd:YAG Laser Posterior Capsulotomy on Ocular Wavefront
Aberrations
5649 - A550
Another Tool in Intraocular Lens Calculation
S. Salas, D. Flikier. Oftalmologia, Instituto de Cirugia Ocular, San Jose, Costa Rica.
J. Levy, I. Klemperer, Z. Ashkenazy, N. Belfair, A. Kratz, T. Lifshitz. Ophthalmology,
Soroka University Medical Center, Beer-Sheva, Israel.
Purpose: To assess the effect of Nd:YAG laser posterior capsulotomy on ocular
wavefront aberrations.
Methods: The wavefront aberrations of the entire optical path of 24 pseudophakic
eyes of 20 patients before and 1 month after Nd:YAG laser posterior capsulotomy were
measured using the Nidek-OPD scan aberrometer. Total, tilt, high order aberrations,
total coma, total trefoil, total tetrafoil, total spherical and total high astigmatism
aberrations were analyzed statistically. Secondary measures included changes in
visual acuity and refraction.
Results: Before Nd:YAG laser posterior capsulotomy , the total higher-order aberrations
root-mean-square (RMS) wavefront aberration was 4.39 ± 2.79 µm. All Zernike modes
were elevated, with total trefoil being a major contributor 1.19 ± 1.2 µm. One month
after the procedure significant decreases in total, tilt, high order aberrations, total
trefoil, total tetrafoil, total spherical and total high astigmatism aberrations were
noted (P < 0.05). No significant changes in total coma aberrations were found (P
> 0.05). Additionally, significant improvement in visual acuity without significant
change in refraction was observed.
Conclusions: Nd:YAG laser posterior capsulotomy causes significant decrease in ocular
wavefront aberrations which can explain a better optical quality after the procedure.
Further research to examine the impact of wavefront aberrations in visual function
after Nd:YAG laser posterior capsulotomy is needed.
CR: J. Levy, None; I. Klemperer, None; Z. Ashkenazy, None; N. Belfair, None; A.
Kratz, None; T. Lifshitz, None.
Support: None
Purpose: To compare the results of intraocular lens (IOL) calculations for cataract surgery
using a formula based in eye ray tracing and the SRK-T formula. Both results are compared
to see which spherical equivalent (SE) approaches the most to the desired refraction (in
this case emmetropia).
Using this formula based in eye ray tracing we calculate IOL by direct measurments,
instead of linear regressions like the SRK-T formula, having another option for IOL
calculation.
Methods: We made a retrospective, single surgeon post surgical analysis on 53 patients
(176 eyes, all of them between 21.5 mm. and 28 mm. of axial length), they were analyzed
using different parameters: mean anterior corneal radius, asphericity, mean posterior
corneal radius, corneal thickness (all of them obtained by Scheimpflug image analysis);
axial length, anterior chamber depth, lens thickness (obtained by A-scan immersion
technique); and other data as actual SE, post operatory desired SE (obtained subjectively
and objectively).
After that we calculated an IOL by SRK-T formula and we calculated the IOL with the
formula based in eye ray tracing. It consists in an objective measurement method that
determines intraocular spacing by means of corrected Scheimpflug images, giving
relationships for key anterior segment parameters incorporating aspheric surfaces.
These parameters are analyzed, using an established formula and based on the principle
of a meridional ray impinging on a surface that follows a straight line using the radial
height at the origin, angle in radians between the ray, optical axis and the distance, with
a technique developed for use with a common spreadsheet computer program.
Then it was compared the post surgical SE using SRK-T recommended IOL, and the
theoretical post surgical SE using the IOL formula based on eye ray tracing, to see which
one approaches the most to the desired SE.
Results: The IOL calculations, on eyes between 21.5 mm. and 28 mm. mean 23.76 mm. (SD
+/- 1.53 mm.), based on SRK-T showed a mean SE 0.05 (SD +/- 1.48) meanwhile the ones
based on the eye ray tracing showed a mean SE 0.12 (SD +/- 0.92), then we compared both
results to see which one approaches the most to emmetropia and there was no statistically
significant difference (P 0.7600) between the group calculated by SRK-T and the group
calculated by the eye ray tracing based formula, for a desired SE.
Conclusions: The formula based on eye ray tracing showed to be as reliable as the
conventionally used SRK-T for IOL calculation, in eyes whose axial length was between
21.5 mm. and 28 mm. adding a new tool when it comes to IOL calculation for cataract
surgery patients.
CR: S. Salas, None; D. Flikier, None.
Support: None
5646-5649
5650 - A551
A Comparative Study of Visual Perceptions and Pain Scores in Vitreo-Retinal
and Cataract Surgery Under Local Anesthesia
U.K. Bhatt1, M. Gregory2, S. Benskin 3, S. Jain1, S. Banerjee1. 1Ophthalmology, University
Hospital of Leicester, Leicester, United Kingdom; 2Ophthalmology, Gartnavel
General Hospital, Glasgow, United Kingdom; 3Ophthalmology, Queen Elizabeth
Hospital, St Michael, Barbados.
Purpose: To compare subjective visual perceptions and pain during vitreo-retinal
(VR) and cataract surgery under local anesthesia (LA).
Methods: Sixty-eight patients undergoing VR surgery under LA in a teaching hospital
VR unit were included (Group A). Age and sex matched controls were selected from
patients undergoing cataract surgery under LA (Group B). Visual perceptions and pain
scores (during anesthesia and the VR procedure separately) were compared in the two
groups. Statistical analysis was performed using Microsoft Excel® software.
Results: Patients’ experiences of seeing colour and light and also pain scores were
significantly different between the two groups (p<0.001 for colour and light sensations,
Fisher’s exact test (FE-test); p<0.001 for pain sensation, t-test) but perception of
movement was not significantly different (p=0.36, FE-test).(See table)
Among the patients in the vitreoretinal group, pain scores were higher with duration
of surgery (p=0.005, t test), history of previous ocular surgery under LA (p=0.03, FEtest) and the type (eg. scleral buckling) of surgery (p<0.004, Chi-square test). There
was no correlation between the intra-operative pain scores and visual perceptions
(p>0.05, Spearman’s correlation).
Conclusions: Subjective visual perceptions and also pain scores during vitreo-retinal
surgery under LA are different from those in cataract surgery. With a increasing
proportion of the VR procedures done under LA, this information can be useful in
better pre-operative counselling of such patients.
Summary of comparison of visual perceptions and pain in vitreoretinal and cataract
surgery groups
Different Modalities
VR Surgery
Cataract Surgery P value
Colors
75% (51/68)
35.29% (24/68)
0.0001 (F. E. Test)
Lights
88.23% (60/68) 60.29% (41/68)
0.0001 (F. E. Test)
Movements
45.59% (31/68) 41.18% (28/68)
0.36 (F. E. Test)
Mean anesthetic pain (Scores) 2.54
2.57
0.4677 (t-test)
Mean surgery pain (Scores)
2.59
1.42
0.00002 (t-test)
CR: U.K. Bhatt, None; M. Gregory, None; S. Benskin, None; S. Jain, None; S.
Banerjee, None.
Support: None
5650
Thursday, May 1, 1:00 PM - 2:45 PM Room 315 Paper Session Program Number Range: 5843-5849
553. Spatial and Temporal Vision Organizing Section: VI
5843 - 1:00PM
The Effects of Fixation Instability on Peripheral Visual Acuity
A.F. Macedo1,2, M.D. Crossland1, G.S. Rubin1,3. 1Department of Vision Rehabilitation,
UCL Institute of Ophthalmology, London, United Kingdom; 2Dep. Physics,
University of Minho, Braga, Portugal; 3NIHR Faculty, London, United Kingdom.
Purpose: People with central scotomas must use peripheral areas of the retina in order
to look at an object. Eye movement control is impaired during this eccentric viewing,
causing fixation instability. It is unclear whether counteracting this fixation instability
improves vision in the peripheral retina. The purpose of this study was to measure
peripheral visual acuity (PVA), with and without crowding, whilst modulating fixation
instability by using gaze-linked stimuli.
Methods: Six observers with normal or corrected-to-normal vision participated in
the study. Peripheral visual acuity was measured with a Landolt “C” target with and
without crowding bars. The target was presented in four retinal positions at 5º and at
10º eccentricity. Gaze position was monitored throughout using an infrared eyetracker
(SMI Eyelink I). The target was presented for up to 500 msec, either with no movement
relative to gaze position (zero instability), with reduced movement relative to eye
movements (damped instability) or with increased movement relative to gaze position
(increased instability). Data were analysed using linear mixed models.
Results: Without crowding PVA was slightly better with increased instability
compared with damped instability (mean improvement = 0.04 logMAR; p < 0.05) but
did not differ significantly from zero instability (mean difference = 0.01 logMAR;
p > 0.05). PVA was equal for damped and zero instability conditions (p < 0.05). In
contrast to the previous result, under crowded conditions PVA decreased markedly
with increased instability compared with the other two conditions (mean reduction
0.13 logMAR, p < 0.001).
Conclusions: Increased fixation instability improves peripheral visual acuity for
uncrowded tasks yet reduces visual performance in the presence of crowding.
For people with unstable fixation, peripheral visual acuity measured with single
(uncrowded) targets is not likely to be a good predictor of performance in real visual
tasks. These results provide further evidence for the importance of fixation stability
on reading ability.
CR: A.F. Macedo, None; M.D. Crossland, None; G.S. Rubin, None.
Support: FCT PORTUGAL - POCTI & FSE - Grant SRFD/BD/27975/2006
5845 - 1:30PM
The Course of Development of Global Hyperacuity Over Lifespan
Y.-Z. Wang1,2, S.E. Morale1, R. Cousins1, E.E. Birch1,2. 1Retina Foundation of Southwest,
Dallas, TX; 2Ophthalmology, UT Southwestern Med. Center, Dallas, TX.
Purpose: Global visual integration is fundamental to shape and face recognition.
While the maturation of local visual function, such as resolution acuity, has been
well documented, less is known about the change of global visual function with age.
In this study, we determined the course of development for a global hyperacuity, the
threshold for detecting the radial modulation of circular shape, over lifespan.
Methods: Three hundred normal subjects, age from 0.17 to 78 years old, participated
the study (n=76, 57, 43, 25, 54, and 45 for age groups <=1yr, 2.5 to 5.9 yrs, 6 to 10 yrs, 10.1
to 20.9 yrs, 21 to 50 yrs and >50 yrs old, respectively). The detection threshold for radial
deformation was determined using a 2AFC, preferential-looking protocol (for <= 1 yr
old) or a 2AFC staircase paradigm, with maximum likelihood threshold estimation.
Resolution acuity was also measured. The developmental course was described by a
curve of 3 segments: the 1st is an exponential function (y=a+a1*(exp[-b1(x-c1)]-1)); the
2nd is a horizontal line (y=a); and the 3rd is a linear function (y=a+b3(x-c2)), where c1 is
the age dividing the 1st and 2nd segments, and c2 dividing the 2nd and 3rd segments.
This curve was used to fit the data of logMAR thresholds for global hyperacuity and
for resolution acuity as a function of age.
Results: Curve fitting reveals that global hyperacuity was 0.30 logMAR at 0.17 yrs of
age, and improved rapidly to -0.56 logMAR at 5.4 yrs of age (0.17 logMAR per year
improvement). Its continuing maturation became slower, reaching to -0.70 logMAR
(the 95% up-limit of adults’ threshold) at 7.5 yrs of age, and to the mean adult level
(-0.86 logMAR, a) at 20 yrs of age (c1). Global hyperacuity started to deteriorate from 60
yrs of age (c 2) at the rate of 0.04 logMAR per decade (10*b3). In comparison, resolution
acuity reached to 0.0 logMAR (20/20) at 5.2 yrs of age, and reached the adult level of
-0.1 logMAR (a) at 11.5 yrs of age (c1). Resolution acuity started to decrease from 55
yrs of age (c2) at the rate of 0.06 logMAR per decade (10*b3).
Conclusions: Similar to vernier alignment acuity, global hyperacuity improves
rapidly during infancy and early childhood but takes longer to reach the adult level
than resolution acuity. The delayed maturation of global hyperacuity suggests that
further development to refine neural circuitry at the cortex level takes place in the
second decade of life.
CR: Y. Wang, None; S.E. Morale, None; R. Cousins, None; E.E. Birch, None.
Support: EY05236
5844 - 1:15PM
Quantifying and Comparing the Effects of Variations in Retinal Illuminance
on Contrast Sensitivity Perimetry (CSP) and Frequency Doubling Technology
Perimetry (FDT2/Matrix)
M.W. Dul1, A. Hot1, W.H. Swanson2. 1Clinical Sciences, SUNY College of Optometry,
New York, NY; 2Optometry, Indiana University, Bloomington, IN.
Purpose: Frequency Doubling Technology (FDT) uses rapid temporal modulation,
for which psychophysical performance can be more susceptible than conventional
perimetry to changes in retinal illumination due to pupil size and lenticular density.
Contrast sensitivity perimetry (CSP) has been implemented with slow temporal
presentation in order to minimize such effects. This study was conducted to quantify
and compare the effects of variations in retinal illuminance on (CSP) and FDT2
(Matrix) perimetry.
Methods: A Zeiss-Humphrey/Welch Allyn Matrix FDT2 perimeter was
used with the threshold N-30 strategy. CSP was performed using a customized station.
FDT2 presented 0.5 cycle/degree spatial frequency gratings in a 5 degree square
window, CSP presented 0.4 cycle/degree Gabor patches in a two-dimensional spatial
Gaussian envelope ~4 degrees in diameter. FDT2 used rapid temporal presentation
(counter-phase flicker at 18 Hz), while CSP used sustained temporal presentation
(Gaussian temporal envelope, ~200 msec). One eye each of 21 younger subjects (23 ±
2 yrs) and ten older subjects (49 ± 8 yrs) were tested with dilated pupils, then retested
with neutral density filters of 0.6, 1.2, and 1.6 log unit in front of the subject’s eye.
For each subject and neutral density filter, mean sensitivity (MS) was computed as
the average sensitivity across all locations. MS versus retinal illuminance data were
fit with a standard adaptation model: MS = A*(log(I/(I+K)), where I is mean retinal
illuminance and A,K are free parameters.
Results: For FDT2, as mean luminance decreased by 1.6 log unit MS decreased by an
average (in log units) of 0.64 for the younger group and 0.78 for the older group. For
CSP, there was less of a decrease: 0.08 (younger) and 0.17 (older). Both datasets were
fit well with the standard adaptation model, which predicted that normal betweensubject differences in pupil diameter could contribute 0.29 log unit (5.8 dB) to the
normal range for the FDT2 and only 0.02 log unit for CSP.
Conclusions: Consistent with a body of psychophysical evidence on the interaction
of temporal frequency and retinal illuminance, we found that reduction in mean
retinal illuminance had more dramatic effects for FDT2 perimetry versus CSP. Factors
contributing to variations in retinal illuminance, such as normal between-subject
variability in pupil size and lenticular density will contribute to normal betweensubject variability in FDT but not CSP.
CR: M.W. Dul, None; A. Hot, None; W.H. Swanson, None.
Support: Glaucoma Institute, SUNY State College of Optometry
5846 - 1:45PM
The Effect of Age on the Area of Complete Spatial Summation for Chromatic
and Achromatic Stimuli
T. Redmond1,2, M.B. Zlatkova1, D.F. Garway-Heath2, R.S. Anderson1,2. 1Vision Science
Research Group, University of Ulster, Coleraine, United Kingdom; 2Moorfields Eye
Hospital, London, United Kingdom.
Purpose: Previous studies have reported an age-related increase in the area of complete
spatial summation (Ricco’s Area) under scotopic conditions (Schefrin et al, 1998; based
on a sample of 50 healthy observers), interpreted as increased convergence from
photoreceptors in compensation for an age-related loss of retinal neurons. We wished
to investigate if the same holds true under photopic conditions for both achromatic
stimuli and chromatic stimuli targeting the S-cone pathway. In addition we wanted
to determine how any change might relate to ganglion cell loss as determined by
measures of peripheral grating resolution.
Methods: Spatial summation curves were measured at 10 deg eccentricity for 57
subjects between the ages 20-69 years using both white-on-white increment stimuli
and blue stimuli superimposed on an intense yellow adapting background (Stiles
two-color threshold method). Ricco’s area was determined using piecewise regression
analysis. Achromatic resolution acuity (grating orientation discrimination) was also
measured at the same peripheral locations as an indicator of retinal ganglion cell
sampling density loss with age in the same subjects.
Results: Results indicate that, while there is a notable increase in threshold for both
achromatic and S-cone stimuli with age, there is no significant change in Ricco’s area
for either stimulus type (one way ANOVA: p>0.3 (achromatic), p>0.5 (chromatic)).
The average size of Ricco’s area for achromatic stimuli in the youngest and oldest age
decades was 0.079deg2 and 0.071deg2 respectively and for chromatic stimuli, the mean
size of Ricco’s area was 0.39deg2 for the youngest decade and 0.49deg2 for the oldest
decade. A significant decrease in resolution acuity, and hence ganglion cell sampling
density, was found as a function of age (one-way ANOVA: p<0.01). Resolution acuity
remained constant until approximately 40 years of age and declined at an average
rate of -0.6dB per decade thereafter.
Conclusions: While retinal ganglion cell density declines with age, this is not
accompanied by a change in the area of complete spatial summation for either
achromatic or s-cone stimuli. These results do not support the hypothesis of a change
in the area of complete spatial summation as a compensation mechanism for the loss
of retinal ganglion cells under photopic conditions.
CR: T. Redmond, None; M.B. Zlatkova, None; D.F. Garway-Heath, Heidelberg
Engineering, F; Carl Zeiss Meditec, F; Optovue, F; Carl Zeiss Meditec, C; Carl Zeiss
Meditec, R; R.S. Anderson, None.
Support: None
5843-5846
Thursday, May 1, 1:00 PM - 2:45 PM Room 315 Paper Session Program Number Range: 5843-5849
553. Spatial and Temporal Vision Organizing Section: VI
5847 - 2:00PM
How Pieces of a Polygon Are Put Together?
5848 - 2:15PM
Hierarchical and Parallel Visual Processing in Parkinson Disease:
Magnocellular Impairment and Motion Integration Deficits Are Independent
L. Liu. School of Optometry, UAB, Birmingham, AL.
Purpose: For patients with advanced retinitis pigmentosa, glaucoma or a retinal
prosthesis, only a small piece of the environment can be visually perceived at any
time. An understanding of how pieces of a visual scene are put together to form a
global percept is important for low vision evaluation and rehabilitation. A polygon
of random vertices is a simple abstraction of an unfamiliar visual object. It can be
displayed by vertices, sides or pieces of different sizes. Normal human subjects’ ability
to use pieces of a polygon to perform symmetry judgment was evaluated.
Methods: Random polygon outlines were generated. Each polygon had 10 vertices,
was 300x300 pixels in size (8.5 deg visual angle at 60 cm), and had a line width of 3
pixels. The polygons had different degrees of axial symmetry and random symmetry
axis. A polygon was displayed in several ways, vertices one-by-one, sides one-byone, and 4, 9, 16, 25 or 36 pieces one-by-one. Each part was presented 100 msec. Parts
could be displayed in sequential or random order. Symmetry axis could be hidden or
shown to the subject before each trial. In an experimental session, polygons of good
symmetry were mixed with asymmetric polygons. The subject’s task was to determine
if a polygon was symmetric or not. Eye movements were not restricted.
Results: Normal subjects could judgment symmetry of a polygon from its pieces, even
when the polygon was cut into 25 or 36 pieces. A 50 to100-trial practice might be needed
to reach an 80-90% correct rate. Presenting the pieces in random order and hiding
symmetry axis had little impact on performance. Random jittering of piece positions
up to 16 pixels had only moderate effect on symmetry judgment. Symmetry judgment
was accurate if sides of a polygon were presented in sequential order, even without
knowledge of symmetry axis, but was impossible if sides were presented in random
order, with or without symmetry axis. A 4-pixel random jittering of side positions
had little effect, but a larger jittering impaired performance. Symmetry judgment
was accurate if isolated vertices of a polygon were presented in sequential order and
with knowledge of the symmetry axis, but was not possible without knowledge of
the axis or when vertices were presented in random order.
Conclusions: Perceiving global characteristics of a polygon from pieces cannot be
explained simply by retinotopic or spatiotopic painting of the retina or visual memory.
At least for the task of symmetry judgment, human subjects use features that are
more complex than vertices or lines, typically corners made of two or more lines
or three or more vertices, either presented simultaneously or sequentially. Visual
field sizes large enough to contain such features are crucial for low vision patients
to perceive large objects.
CR: L. Liu, None.
Support: NEI Grant R03 EY014904
M. Castelo-Branco, M. Mendes, F. Silva, G. Januário, J. Massano, C. Januário, A. Freire.
Visual Neuroscience Laboratory, IBILI-Fac of Med of Univ of Coimbra, Coimbra,
Portugal.
Purpose: Motion processing involves multiple hierarchical steps, from the
magnocellular pathway, sensitive to high temporal frequency modulations, to
subsequent motion integration within magno recipient regions in the visual cortical
dorsal stream. We have asked the question whether motion integration deficits in
Parkinson Disease (PD) can be explained by visual deficits in earlier processing nodes.
An alternative hypothesis is that convergence of magno inputs may be sufficient to
compensate for peripheral loss of these inputs.
Methods: Deficits in the afferent magnocellular pathway, measured with a contrast
sensitivity task that uses a sinusoidal grating stimulus at high temporal (25 Hz) and low
spatial frequencies (0.25 cycles per degree) were compared with speed discrimination
of local dots moving in random directions, speed and direction discrimination of
moving surfaces, direction discrimination and motion integration as measured by
2D coherence thresholds.
Results: We have found that low-level magnocellular impairment in PD does
not explain deficits in subsequent steps in motion processing. In fact, high-level
performance was abnormal only for tasks requiring perception of coherently moving
tasks, with partial compensation being observed for other tasks requiring processing
of motion attributes.
Conclusions: We conclude that dorsal stream deficits in PD have a high-level visual
cortical basis are not explained by low level magnocellular damage. These findings
further challenge visual magnocellular theories in dyslexia that postulate that
magnocellular dysfunction is causally related to motion integration deficits.
CR: M. Castelo-Branco, None; M. Mendes, None; F. Silva, None; G. Januário, None; J.
Massano, None; C. Januário, None; A. Freire, None.
Support: POCI_SAU-NEU_60281_2004
5849 - 2:30PM
Behavioral and Multi-Photon Analysis of Plaid Stimulus Integration in the
Zebrafish Visual Tectum
O. Biehlmaier1, S.C.F. Neuhauss1, F. Helmchen2, B. Kampa2. 1Neurobiology - Institute of
Zoology, University of Zurich, Switzerland; 2Brain Research Institute, University of
Zurich, Switzerland.
Purpose: To determine the direction of object motion, multiple local motions must
be combined and computed in the brain. When superimposed, two moving gratings
appear to form a single ‘plaid’ pattern. The two grating components generate individual
responses in local motion detectors. In higher brain areas this information can be put
together by pattern-selective cells that respond to the movement of the plaid pattern
rather than the individual gratings. Here, we analyze the integration of plaid stimuli
in the visual system of zebrafish larva.
Methods: We examined zebrafish larva by measuring tectal activity as well as their
behavioral response to different visual stimulation patterns. Larva were immobilized;
then we presented grating patterns for 1s moving in 45° angles to the upper right
(45°-right), upper left corner (45°-left) of the stimulation screen, or an overlay of
these stimuli, resulting in a plaid stimulus moving upwards. Tectal activity to these
stimuli was recorded by 2-photon microscopy after bolus-injection of OGB-1/AM.
We used the same stimuli for the behavioral experiments but presented the stimuli
on a horizontally mounted LCD-screen for 25s. The optomotor response (OMR) of
the larva to the respective stimuli was assessed in a 20cm petri dish, separated into
3 sectors referring to the 3 apparent stimulus directions (left, mid, right).
Results: So far, we identified several direction-sensitive cells in the visual tectum of 5
dpf larva. Stimuli moving in the preferred direction evoked large calcium transients
(~30% ΔF/F) measured by selecting regions of interests surrounding the somata.
In our OMR-setup we found that the larva performed the behavior in the expected
directions. If exposed to the 45°-right stimulation, 55.7% of the larva followed the
stripes and accumulated in the right sector of our setup (Other sectors: left 4.9%;
mid 11.5%). If stimulated with the 45°-left stimulation, 47.5% of the larva were found
in the left sector. The plaid stimulus was detected as a straight movement and thus
29.5% of the larva were found in the mid sector (left: 4.9%; right: 9.8%). Further twophoton recordings will aim on the spatial organization of direction and orientation
sensitive cells in the tectum. In addition, we seek to identify pattern-selective cells
and their spatial organization.
Conclusions: So far, these data are consistent with the hypothesis that zebrafish
larva can see moving plaid patterns and follow the movement of the pattern rather
than its components.
CR: O. Biehlmaier, None; S.C.F. Neuhauss, None; F. Helmchen, None; B. Kampa,
None.
Support: Velux Foundation; Swiss National Science Foundation (SNSF)
5847-5849

Sunday, April 27, 2:30 PM - 4:15 PM Hall B/C

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