ARVO 2015 Annual Meeting Abstracts 541 Contact lens Thursday

Transcription

ARVO 2015 Annual Meeting Abstracts
541 Contact lens
Thursday, May 07, 2015 12:00 PM–1:45 PM
Exhibit Hall Poster Session
Program #/Board # Range: 6066–6116/C0001–C0051
Organizing Section: Cornea
Contributing Section(s): Lens
Program Number: 6066 Poster Board Number: C0001
Presentation Time: 12:00 PM–1:45 PM
Improving Underwater Vision With Amphibious Contact Lenses
Sierra M. Warren1, Ashley Valdez2, Jim Schwiegerling2.
1
Biochemistry, San Diego State University, San Diego, CA; 2Optical
Sciences, University of Arizona, Tucson, AZ.
Purpose: Improving underwater vision is greatly desired by
water sport enthusiasts and, with the newly designed underwater
amphibious contact lenses, clear vision is provided. The project’s
inspiration came by a simple and interesting adaptation in nature by
the “four-eyed” fish Anableps anableps. The eyes of the fish contain
2 corrective regions: one for vision in air and the other below water.
A human’s eye is optimally designed for in-air viewing with perfect
vision, requiring a power of 43 diopters of accommodation. Each
environment requires a different power range, permitting the viewer
to observe images focused clearly on the retina.
Methods: The corrective crystalline lenses tested are asymmetric,
unlike commonly used masks and goggles which limit the user’s field
of view. The lenses are specifically prescribed for the wearer’s visual
prescription to correct any defocus or astigmatism. They were tested
in a number of environments and conditions for visual acuity and
compared to goggles. Environments ranged from salt water to fresh
water. The visual acuity was measured by a Snellen eye chart specific
to the testing area. In addition to testing visual acuity at near and
distant points, resolution limit, pattern detection and recognition, and
color were tested.
Results: In Arizona at noon, the test results determined hyper-acuity
reaching 20/16. The amphibious contact lenses had full number
recognition to 20/25 and partial at 20/20. This concluded that the
lenses are able to correct vision impairment and aberrations. Results
were conclusive for pattern recognition for letters versus numbers
read on Snellen charts. No matter the pattern on the chart the user
was able to recgonize letters, shapes, and numbers to a visual acuity
of 20/16 average.
Conclusions: This indicates that the wearer had improved visual
acuity under water and above water with the contact lenses in
the same conditions. In addition to increased visual acuity, there
was immediate awareness of a full field of view. Varying pattern
recognition chart types were concluded with positive visual acuity
results. Overall, the lenses performed as expected. There should be
decreased acuity in dark, murky conditions and a standard 20/16
in illuminated conditions. Future work involved in this research is
to determine quantitative data for the field of view and use color
patterns, for water absorbs red lambda and the intensity of red should
decrease.
Commercial Relationships: Sierra M. Warren, None; Ashley
Valdez, None; Jim Schwiegerling, None
Support: 2015 ARVO/SACNAS Eye and Vision Research Award
Impact of Contact Lens Wear on Conjunctival Goblet Cells
Luisa H. Colorado, Yahya Alzahrani, Nicola Pritchard, Nathan
Efron. Queensland University of Technology, Institute of Health and
Biomedical Innovation, Brisbane, QLD, Australia.
Purpose: Controversy exists regarding changes in conjunctival
goblet cell densities (CGCD) after contact lens wear (CLW). To
investigate changes in CGCD and symptoms of dry eye in CLW, we
conducted a six-month longitudinal, observational, dispensing study
using laser scanning confocal microscopy (LSCM) and conjunctival
impression cytology (CIC) to measure CGCD of the nasal bulbar
conjunctiva.
Methods: A total of eighty-three (83) non-contact lens wearers
were enrolled in the study. Sixty (60) participants were fitted with
disposable hydrogel lenses with follow-up at one week and one and
six months of daily wear. Twenty-three (23) age-balanced non-contact
lens-wearing participants, assessed at the same time intervals, acted
as the control group. Participants with history of CLW for at least
6 months, pregnancy and breastfeeding, ocular trauma or surgery,
ocular surface dysfunction, classification as symptomatic for dry
©2015, Copyright by the Association for Research in Vision and Ophthalmology, Inc., all rights reserved. Go to iovs.org to access the version of record. For permission
to reproduce any abstract, contact the ARVO Office at pubs@arvo.org.
eye (DE) based on answers to DEQ-5 and a sign of DE evaluation,
current or long-term use of topical ocular medication, and ocular
or systemic disease that may affect the conjunctiva were excluded.
After one week all participants were assigned into two further
categories related to dry eye; symptomatic (n=25) and asymptomatic
(n=35) based on answers to the contact lens dry eye questionnaire-8
(CLDEQ-8). At each visit participant measurements included DEQ-5
for controls and CLDEQ-8 for CL wearers, non-invasive tear film
break-up time, ocular surface assessment and phenol red thread
(PRT) test. Nasal bulbar conjunctiva was imaged using LSCM
(HRTIII with Corneal Rostock Module). CIC was obtained a few
minutes later from the same area evaluated with LSCM. The CGCD
was calculated as the number of cells per mm2 of tissue.
Results: CGCD in the CLW group decreased significantly over six
months as assessed with both LSCM and CIC (p<0.001) CGCD
decreased by 23% and 27% from baseline in the symptomatic group
as assessed using CIC and LSCM, respectively, and by 19% in the
asymptomatic group using both techniques. The control group did not
change significantly from baseline at 1 and 6 months (P=0.054).
Conclusions: CGCD is reduced after short-term contact lens wear in
both symptomatic and asymptomatic wearers.
Commercial Relationships: Luisa H. Colorado, None; Yahya
Alzahrani, None; Nicola Pritchard, None; Nathan Efron, None
Quantitative analysis of microvascular network of the lid wiper
area in contact lens wearers
Jianhua Wang1, Hong Jiang1, Xinjie Mao2, 1, Wentao Yan2.
1
Ophthalmology, Bascom Palmer Eye Inst Lib, Miami, FL;
2
Ophthalmology and Optometry, School of Ophthalmology and
Optometry, Wenzhou Medical University, Wenzhou, China.
Purpose: To demonstrate the feasibility of quantitative analysis of
microvascular network of the lid wiper area of the human eye imaged
with our functional slit-lamp biomicroscopy (FSLB).
Methods: FSLB was adapted from a traditional slit-lamp microscope
by attaching a digital camera to image the conjunctiva to take images
of the lid wiper area, which were compared to the images of the
tarsus. Nine human subjects including 3 habitual contact lens wearers
were imaged twice at one visit. Only the left eye was imaged. Custom
software for automated segmenting the microvascular network has
been developed and described in our previous publication (Jiang
et al. Microvascular Research, 2014;92:62-71). The same software
was used to segment the microvascular network of the lid wiper and
tarsus. We used the fractal analysis toolbox from Benoit™ (TruSoft
Benoit Pro 2.0, TruSoft Inc., St. Petersburg, FL) to analyze the fractal
dimension of the microvascular network. Multifractal analysis (D0)
was performed to quantify the fractality (density and complexity)
of the vascular network of the lid wiper area (Fig. 1) and the tarsal
conjunctiva (Fig. 2). The coefficient of repeatability (CoR) of the
tests was analyzed.
Results: D0 of the lid wiper area was 1.556 ± 0.209 (mean ± SD)
for the first session and 1.572 ± 0.213 for the second session. The
CoR of these measurements was 7.7%. D0 was 1.358 (SD: 0.213) in
contact lens wearers and 1.667 (SD: 0.116) in healthy subjects (P =
0.057). D0 of the tarsus was 1.706 ± 0.053 for the first time and 1.709
± 0.053 for the second time. The CoR of these measurements was
3.5%. D0 was 1.703 (SD: 0.005) in contact lens wearers and 1.719
(SD: 0.064) in healthy subjects (P = 0.246). The difference of the
microvascular network was significant (P = 0.046) between the lid
wiper and tarsus.
Conclusions: This is the first time to demonstrate the feasibility of
quantitatively analyzing the microvascular network of the lid wiper
area and the tarsal area using FSLB. Further studies will need to be
done on a large sample of subjects and patients with diseases and
conditions. The approach could be applied to study dry eye, contact
lens wear and other ocular surface diseases involving the damage and
inflammation of the lid wiper and tarsal conjunctiva.
Commercial Relationships: Jianhua Wang, NIH (F); Hong Jiang,
NIH (F); Xinjie Mao, None; Wentao Yan, None
Support: Supported by research grants in part from the NIH
EY021012, EY021336, NIH Center Grant P30 EY014801, Research
to Prevent Blindness (RPB), Department of Defense (DODGrant#W81XWH-09-1-0675).
Comparisons between Age, Gender, Lens Type and Lid Wiper
Epitheliopathy with Soft Contact Lens Comfort
Marc-Matthias Schulze1, Sruthi Srinivasan1, Sheila B. HicksonCurran2, Youssef Toubouti2, Stephanie Cox3, Aftab Mirza4, Jason J.
Nichols3, Phillip B. Morgan4, Lyndon W. Jones1. 1Centre for Contact
Lens Research, University of Waterloo, School of Optometry and
Vision Science, Waterloo, ON, Canada; 2Johnson and Johnson Vision
Care, Inc., Jacksonville, FL; 3School of Optometry, University of
Alabama at Birmingham, Birmingham, AL; 4Eurolens Research,
Faculty of Life Sciences, University of Manchester, Manchester,
United Kingdom.
Purpose: Comfort is an important component of successful contact
lens (CL) wear. The purpose of this study was to investigate if there
are differences in comfort levels among soft CL (SCL) wearers when
wearing their habitual lenses.
Methods: Subjective comfort with their habitual lenses was assessed
in 246 SCL wearers who attended a screening visit at one of three
sites of a multi-centre study. Participants attended the visit wearing
their habitual SCLs, and answered questions regarding their habitual
CL experience using the Contact Lens User Experience (CLUETM)
questionnaire. CLUE comfort scores range from 0 to 120, with
higher scores indicating a more positive response. After removal of
the habitual CLs, lid wiper epitheliopathy (LWE) was assessed using
lissamine green and sodium fluorescein dyes (0-3 Korb scale). For
each participant, a final LWE grade was calculated as the averaged
grade of the two dyes and then categorized into no LWE (grade
0), mild (0.25-1.00), moderate (1.25-2.00), and severe (2.25-3.00).
Comparisons of comfort scores across age group (19-29, 30-39,
40-49, 50+), gender, habitual lens types and categorized LWE groups
were conducted using t-tests on least-square means (LSM) from a
linear mixed model. The step-down Dunnett’s method was used to
control type I error inflation.
Results: Comfort scores (LSM±StError) with habitual lenses were
significantly higher in females than in males (69.9±2.5 vs 64.1±2.9;
p=0.037). There was also a significant difference in CLUE comfort
for age group, with the 40-49 year olds showing significantly
greater comfort than the 18-29 age group (74.0±3.5 vs 60.2±2.1;
p<0.001). There were no differences in comfort scores between LWE
categories, with comfort scores of 62.7±4.0 (no LWE), 66.3±2.6
(mild), 67.1±2.8 (moderate) and 71.9±4.3 (severe; all p=0.376).
There was a significant difference in comfort scores depending on
habitual lens type (p=0.020). Narafilcon A (80.6±6.1) was found
to have higher comfort scores (all p<0.04) compared to senofilcon
A (66.3±3.6), lotrafilcon B (59.4±3.9), comfilcon A (59.6±4.0) and
“other” (65.5±2.6), with no difference (p>0.05) compared to etafilcon
A (70.3±5.3).
Conclusions: CLUE comfort was significantly different depending
on age and gender, while there was no difference for categorical
LWE. Narafilcon A wearers reported the highest comfort with
habitual CLs.
Commercial Relationships: Marc-Matthias Schulze, None; Sruthi
Srinivasan, None; Sheila B. Hickson-Curran, Johnson & Johnson
Vision Care, Inc. (E); Youssef Toubouti, Johnson & Johnson Vision
Care, Inc. (E); Stephanie Cox, None; Aftab Mirza, None; Jason
J. Nichols, Johnson & Johnson Vision Care, Inc. (F); Phillip B.
Morgan, Johnson & Johnson Vision Care, Inc. (F); Lyndon W.
Jones, Johnson & Johnson Vision Care, Inc. (F)
Support: Johnson and Johnson Vision Care, Inc.
Clinical Trial: NCT01791517
Decreased Lens Clearance at 20 Minute Intervals Over 2 Hours
of Small-Diameter Scleral Lens Wear
Cherie B. Nau, Michael Helland, Muriel Schornack. Ophthalmology,
Mayo Clinic, Rochester, MN.
Purpose: Small-diameter scleral lenses were previously found
to settle by about 50% after two hours of wear. The rate of lens
settling over time is further evaluated in this study. We examined
the clearance between the lens and the cornea at 20 minute intervals
during the first two hours of small-diameter scleral lens wear.
Methods: Twelve participants, seven men and five women age 21-43
years (29 ± 7 years, mean ± SD) with healthy eyes (no history of eye
disease or surgery and no previous scleral lens wear), were fitted on
one eye with a 15-mm diameter Jupiter scleral lens (Visionary Optics,
Front Royal, VA). Lenses were selected from a diagnostic fitting set
to provide 200-300 mm clearance between the lens and central cornea
immediately after application. Within 5 minutes after placement,
slit images of the lens and cornea were recorded by Scheimpflug
photography (Pentacam, Oculus, Inc.). The clearance between the
posterior surface of the lens and the anterior surface of the cornea
was measured twice, over the central cornea, in each of two vertical
Schemipflug images, using the caliper tool in the Pentacam analysis
software. Clearance was recorded as the average of these four
measurements. Scheimpflug photography was repeated every 20
minutes for two hours, and the central clearance was measured in
the same manner. The corneal clearance for each measurement was
compared to the initial clearance and to the previous time point by
using a paired t-test.
Results: Scleral lens clearance after initial application was 152
± 72 mm (range: 49-315 mm). After two hours of wear, clearance
was reduced to 80 ± 55 mm (range: 26-237 mm; p = 0.009), a 47%
reduction in corneal clearance. Percent reduction in clearance
between successive time intervals was 15%, 2%, 0%, 11%, 8%,
and 21% at 20, 40, 60, 80, 100, and 120 minutes after application
respectively. Difference in clearance between initial and 20 minutes
(128 ± 67 mm, p = 0.005), and initial and 120 minutes were
significant. However, the only time interval with a statistically
significant change in vault was after the first 20 minutes of wear,
difference between other successive intervals were not significant.
Conclusions: There is an initial reduction of central clearance within
20 minutes of 15-mm scleral lens wear. The lens continues to settle
after two hours of continuous wear. The potential for lens settling
needs to be considered when fitting these lenses.
Commercial Relationships: Cherie B. Nau, None; Michael
Helland, None; Muriel Schornack, None
Support: RPB, Mayo Foundation, NIH UL1 TR000135, Scleral Lens
Education Society
Change in Fluid Reservoir Turbidity at 20-Minute Intervals Over
2 Hours of Small Diameter Scleral Lens Wear
Muriel Schornack, Michael Helland, Cherie B. Nau. Ophthalmology,
Mayo Clinic, Rochester, MN.
Purpose: Accumulation of debris in the post-lens fluid reservoir is
frequently observed during scleral lens wear, but changes in fluid
reservoir turbidity have not yet been quantified. This study describes
a method of quantifying changes in turbidity of the fluid reservoir
by measuring its optical density, and compares values of the optical
density of the reservoir at 20 minute intervals during the first two
hours of 15-mm scleral lens wear.
Methods: Twelve participants, seven men and five women age 21-43
years (29 ± 7 years, mean ± SD) with healthy eyes (no history of
eye disease or surgery and no previous scleral lens wear), were fitted
on one eye with a 15-mm diameter Jupiter scleral lens (Visionary
Optics, Front Royal, VA). Lenses were selected from a diagnostic
fitting set to provide 200-300 μm clearance between the lens and
central cornea. Within 5 minutes after placement, slit images of
the lens and cornea were recorded by Scheimpflug photography
(Pentacam, Oculus, Inc.). The optical density of the fluid reservoir
was assessed midway between the back surface of the lens and the
anterior surface of the cornea in center of the vertical Scheimpflug
image using the Pentacam’s densitometry analysis software in two
images. Scheimpflug photography was repeated every 20 minutes
for two hours, and densitometry was recorded in the same manner at
each interval. Its value for each measurement was compared to the
original value and to the value at the previous time interval by using
a paired t-test.
Results: Densitometry analysis of the fluid reservoir after initial
placement of the lens was 5.4 ± 1. 6% (range: 4.1-10.4%). After
two hours of lens wear, optical density had increased to 10.7± 4.0%
(range: 6.1-20.5%), a 97% increase. This change was statistically
significant (p<0.001). Statistically significant changes were noted
between application and 20 minutes (p=0.003) and between 20 and
40 minutes (p=0.01), but changes in density were not statistically
significant between any other consecutive intervals.
Conclusions: Optical density of the post-lens fluid reservoir increases
most rapidly during the first 40 minutes of 15-mm scleral lens wear.
Fluid reservoir optical density continues to increase during two hours
of continuous wear. Quantification of fluid reservoir turbidity will be
necessary as we seek solutions to this common clinical phenomenon.
Commercial Relationships: Muriel Schornack, None; Michael
Helland, None; Cherie B. Nau, None
Support: Mayo Foundation, Research to Prevent Blindness, NIH
UL1 TR000135, Scleral Lens Education Society
Silicone Hydrogels as Drug Delivery Devices for Various Ocular
Therapeutics
Frances Lasowski, Heather Sheardown. Chemical Engineering,
McMaster University, Stoney Creek, ON, Canada.
Purpose: Contact lenses are an attractive, minimally-invasive
alternative to eye drops for various ocular therapeutics, such as
roscovitine, atropine and timolol maleate for use in retinoblastoma,
myopia and glaucoma conditions respectively. However, the uptake
and release characteristics of these drugs vary greatly depending
on the properties of the silicone hydrogel. Therefore, model lenses
containing various drug loadings have been developed to determine
the effect of material composition on subsequent drug release.
Methods: The model lenses contained various combinations of
dimethylacrylamide (DMA), methacryloxypropyltris(trimethylsiloxy)
silane (TRIS) and a hydroxyl-modified TRIS (modified TRIS).
Drugs were loaded into the materials either directly during synthesis
or by subsequent swelling in a drug solution. Release studies were
performed into PBS solutions using UV- spectroscopy and HPLC
to quantify release of each drug. Swelling, extraction, uptake and
contact angle studies were also completed to characterize the
materials.
Results: Most materials showed an appropriate water content (greater
than 20%). The incorporation of the modified TRIS resulted in a
quicker drug release for materials where the drug was directly loaded
into the materials, though many showed sustained release greater
than two weeks. As anticipated, materials containing both regular
and modified TRIS (such as 80:10:10 DMA:TRIS:modified TRIS)
showed drug release levels in between that of the single-silicone
materials, though the release was more similar to the regular TRIS
(such as 80:20 DMA:TRIS); this is seen in Figure 1 for one of the
drugs studied. Similarly materials with greater DMA content tended
to release the drugs faster than those with lower DMA contents.
These results demonstrate that the drug release is highly correlated to
the swelling of the material, though the amount of drug loading and
method of loading is also important.
Conclusions: Alterations to the amount and method of drug loading,
as well as the material compositions, alter the drug release kinetics.
It is possible to sustain drug release for two weeks, the normal wear
time of a contact lens, while maintaining appropriate contact lens
material properties. This shows contact lenses are feasible for drug
delivery to various ocular tissues.
Figure 1. Roscovitine release from various material compositions
loaded by soaking (material compositions given in mole percent).
Commercial Relationships: Frances Lasowski, None; Heather
Sheardown, None
Support: NSERC 20/20 Ophthalmic Network Grant
Improvement in Vision and Ocular Function with Prosthetic
Replacement of the Ocular Ecosystem (PROSE) Scleral Lens
Therapy in Exposure Keratopathy Patients
Jasdeep S. Chahal, J M. Heur, Gloria Chiu. USC Eye Institute,
University of Southern California, Los Angeles, CA.
Purpose: Exposure keratopathy, a desiccation of the cornea caused
by incomplete lid closure, can be refractory to conventional therapies
such as topical lubrication and lid surgery. We used a retrospective
interventional case series to test the hypothesis that PROSE therapy,
using custom scleral devices, would improve visual acuity and ocular
comfort in patients with exposure keratopathy.
Methods: This study was approved by the USC IRB. We analyzed
charts from September 2009 through June 2014 in a single multispecialty institutional practice. 29 patients were identified with the
diagnosis of exposure keratoconjunctivitis, lagophthalmos, ectropion,
or lid retraction or lag, and with a referral to USC Eye Institute
after failing conventional therapies. Eighteen of 25 patients deemed
PROSE candidates completed the fitting process, and 26 eyes of 18
patients were included in the study. Patients with highly irregular
conjunctival surfaces or glaucoma tube shunts were excluded due
to the inability to fit them with a PROSE device. The majority of
candidates who did not start or complete their treatment were either
lost to follow-up or chose not to proceed for financial reasons. Visual
acuity and function were assessed before and after PROSE treatment
using the Snellen chart and the Ocular Surface Disease Index (OSDI)
survey. The OSDI survey is a 12- question, validated measure of
dry eye disease. A two-tailed Student’s t-test was used for statistical
analysis.
Results: Visual acuity improved from 0.60 ± 0.68 logMAR prePROSE to 0.25 ± 0.34 logMAR post-PROSE, p= .0018, n=26 eyes,
equivalent to an improvement of 20/79 to 20/36 on the Snellen chart.
OSDI scores improved from 56.54 ± 29.75 pre-PROSE to 24.98 ±
21.23 post-PROSE, p= .00043, n=12 patients.
Conclusions: The results of this study support our hypothesis that
PROSE therapy is effective in improving visual acuity and ocular
comfort in patients with exposure keratopathy.
Commercial Relationships: Jasdeep S. Chahal, None; J M. Heur,
None; Gloria Chiu, None
Support: An Unrestricted grant from Research to Prevent Blindness,
New York, NY 10022.
Measuring Oxygen Levels Under Scleral Lenses of Different
Clearances
Claude J. Giasson, Jeanne Morency, Langis Michaud. School of
Optometry, University of Montreal, Montreal, QC, Canada.
Purpose: To measure the percent partial pressure in oxygen under
rigid gas permeable scleral lenses of different clearances.
Methods: The right eye of 8 normal subjects was equipped with
2 scleral lenses (SL200 and SL400) of equal thicknesses (Boston
XO2, diameter:18 mm), but adjusted to produce a post-lens layer
thickness (clearance) of 200 and 400 mm. The thickness of the liquid
layer beneath the center of these scleral lenses was measured with an
optical coherence tomograph after 5 minutes of wear. As shortly as
possible after a 5 minute-exposure to gases with oxygen tensions of
0, 1.01, 2.50, 5.00, 10.00 and 20.9%, pO2 levels were measured at
the corneal surface with a Clark electrode and an electrometer (PHM
73, Radiometer, Copenhagen) linked to a computer. The exponential
decay of oxygen upon corneal application was calibrated with a nonlinear regression using the Levenberg Marquardt iteration algorithm.
A linear regression was done between the obtained exponential
decay coefficients and the corresponding percentage of oxygen in
the calibrationg gas. Using this regression, it was then possible to
obtain with the decay observed after 5 minute of wear of SL200 and
SL400, an estimate of the oxygen partial pressure percentage on the
corneal surface under SL200 and SL400. Differences between LS200
and LS400 in terms of oxygen percentage equivalent or liquid layer
thicknesses were tested for significance with paired t tests.
Results: Mean equivalent oxygen percentage beneath SL200 and
SL400 were 9.0 ± 2.6 and 6.7 ± 1.9 %, respectively. The thickness
of the fluid trapped under the lens were 240 ± 35 and 435 ± 33 mm
for the SL200 and SL400, respectively. Both of these differences
between the SL200 and SL400 were statistically significant (p <
0.05).
Conclusions: As predicted by previous calculations of oxygen
transmissibility of scleral lens systems when applying the concept
of resistors in series of the lens and of the tear film thickness
(Michaud, Contact Lens & Anterior Eye 2012; 35 (6): 266–271),
we demonstrate that increased thickness in the layer of fluid trapped
under a scleral lens reduces the oxygen tension available to the
cornea.
Commercial Relationships: Claude J. Giasson, None; Jeanne
Morency, None; Langis Michaud, None
PROSE in the pediatric population
Elan A. Rosenblat, Kelley J. Bohm, Michelle Lee, Kimberly C. Sippel,
Cecilia Nicols, Jessica B. Ciralsky. Ophthalmology, Weill Cornell
Medical College, New York, NY.
Purpose: To evaluate the tolerability and benefit of PROSE in the
pediatric population.
Methods: Retrospective case series of five pediatric patients who
were fit with the PROSE prosthetic device at our institution were
reviewed. All patients were fit by an Optometrist who completed
the Boston Foundation for Sight Clinical Fellowship in Prosthetic
Replacement of the Ocular Surface Ecosystem (PROSE). We
analyzed the visual acuity at contact lens fitting, at three months
and at the most recent exam (mean= 17 months) as our primary
endpoints. All data was analyzed using the Student’s paired t-test.
Results: Eight eyes of 5 subjects, aged 3 to 12 years at initial visit,
who underwent fitting with the PROSE prosthetic devices were
reviewed. The indication for using the PROSE prosthetic device
was severe ocular surface disease which was evident on exam. The
average visual acuity (VA) at the initial prose fitting was 0.928
logMAR, 0.783 logMAR at 3 months, and 0.658 logMAR at the
most recent visit. Initial versus most recent vision demonstrated a
statistically significant improvement (p=0.01). Initial vs. 3 month
(p= 0.7) did not show a statistically significant improvement. All
patients were succsessfully fit by their second visit and there were no
complications assoicated with PROSE use.
Conclusions: The PROSE prosthetic device has been used with
success in patients with severe ocular disease. Although pediatric
patients are often seen as more difficult to fit, this study demonstrates
the viability and utility of using PROSE in the pediatric population.
Commercial Relationships: Elan A. Rosenblat, None; Kelley J.
Bohm, None; Michelle Lee, None; Kimberly C. Sippel, None;
Cecilia Nicols, None; Jessica B. Ciralsky, None
PROSE Treatment for Pediatric Patients with Neurotrophic
Keratitis
Crystal D. Remington, Deborah S. Jacobs. Boston Foundation for
Sight, 501(c)3, Needham, MA.
Purpose: Neurotrophic keratitis can be very challenging to manage
in the pediatric population. Tarsorrhaphy as a treatment option may
contribute to amblyopia and may be unacceptable cosmetically.
Clinicians may be reluctant to resort to therapeutic contact lens in
cases of reduced corneal sensation in children due to risk of infection.
Our purpose is to report the outcome of five pediatric cases of
neurotrophic keratitis managed with prosthetic replacement of the
ocular surface ecosystem (PROSE) treatment. PROSE treatment
utilizes custom-designed and fabricated prosthetic devices that
are applied and removed on a daily basis to support ocular surface
functions in complex corneal disease.
Methods: Retrospective review of medical records of five patients
age 13 years or less who were referred to a single center for PROSE
treatment after failure of conventional measures for treatment of
congenital or acquired neurotrophic keratitis.
Results: Ages ranged from 3 to 13 years at initial consultation for
PROSE treatment. Three patients were female and two were male.
Neurotrophic keratitis was unilateral in 4 cases and bilateral in
1 case. Underlying basis for neutrotrophic keratitis was familial
dysautonomia (1 case), resection of Arnold-Chiari malformation (2
cases) resection of hemangioma (1 case), and idiopathic/presumed
herpes simplex virus (1 case). Three eyes in three children entered
with epithelial breakdown, and were managed with daily wear of
PROSE device and ointment at night. Best corrected vision at entry
for older children ranged from 20/200 to 20/40 and improved to
range of 20/50 to 20/20. For the two children age 3 at entry, vision
was fix and follow each eye (1 patient) and 20/130 improving to
20/94 after 2 months (1 patient). In every eye there was reduction of
staining and epithelial irregularity. In one case there was reduction
of corneal opacity with concomitant topical steroid use. There were
no complications of microbial keratitis during documented wear of 6
months to 10 years, including one patient in which there was 1 year
of concomitant topical steroid use.
Conclusions: PROSE treatment is a useful option for preserving
corneal integrity and vision in pediatric cases of neurotrophic
keratitis.
Slit lamp photo with NaFl iin patient with history of surgery for
Arnold-Chiari malformation showing improvement in ocular surface
staining after 5 months of PROSE treatment.
Commercial Relationships: Crystal D. Remington, Boston
Foundation for Sight, 501(c)3 (E); Deborah S. Jacobs, Boston
Foundation for Sight, 501(c)3 (E)
Creation of Scleral Lens from Virtual Eye Model
Christine W. Sindt1, Bruno Lay2. 1Ophthalmology, University of Iowa,
Iowa City, IA; 2ADCIS, Saint Contest, France.
Purpose: Highly irregular eyes often elude optical correction, require
costly contact lens fitting, have limited comfortable wearing time and
require frequent visits to major medical centers.We set out to design
a completely custom scleral lens which matches the exact contours
of the globe and is made with highly oxygen transmissible material
to increase fitting accuracy,comfort and vision, while decreasing
cost and chair time.Low tech and cost affordable molding techniques
allow for ocular contour capture done in local communities anywhere
in the world,with high tech software in a central location providing
highly customized lenses.
Methods: Using a low viscosity, addition polymerizing polyvinyl
siloxane precision impression material with hydrophilic properties,
an impression mold is obtained of the globe.The concave surface
of the mold is scanned using a 3-D scanner, generating a model
mesh of points in the 3D space. EyePrintPRO Designer software
automatically computes the four zone back surfaces of the lens:First,a
3D sphere cap defines the optic zone.Secondly,the transition zone
is defined by a set of splines which coordinate to the surface of the
impression.The landing zone is defined as a surface that covers the
scan with a minimum clearance.The lens back surface is completed
by an Edge Lift zone. The user can manually tune each zone
clearance and diameter for both back and front surfaces, add some
extra clearance on painful areas (bumps) and see the changes in
real time in the 3D viewer.The software is also capable of raising
warnings when the contact lens hits the model in one or more points.
When both surfaces have been computed, the software generates
files that can be inputted to a lathe to mill the lens. OCT analysis was
performed to validate the virtual (designed) vs actual fit.
Results: OCT analyses shows the EyePrintPRO scleral
lens follows the contour of the globe, including toric
scleras,pingueculas,pterygiums, filtering blebs and irregular
corneas.The EyePrintPRO creates consistent vault over the
cornea and limbus with no impingement of scleral vessels.The
EyePrintPRO has no rotation,allowing for custom optics including
multifocals,torics,decentered optics and prism in any direction.
Conclusions: Highly custom,high oxygen transmission scleral
lenses,with consistent vault,can be obtained from impression molding
of the eye.
Commercial Relationships: Christine W. Sindt, Alcon Vision Care
(C), Allergan (C), EyePrint Prosthetics (I), NovaBay Pharmaceuticals
(C), PCT/US2014/017815 (P); Bruno Lay, EyePrint Prosthetics (C)
Tissue compression following short-term miniscerlal contact lens
wear
Stephen J. Vincent, David Alonso-Caneiro, Michael J. Collins.
School of Optometry and Vision Science, Queensland University of
Technology, Brisbane, QLD, Australia.
Purpose: To quantify the regional (nasal, superior, temporal and
inferior quadrants) and location specific (limbus to sclera) effects
of short-term miniscleral contact lens wear on the morphometry of
anterior ocular structures adjacent to the scleral lens landing zone.
Methods: Optical coherence tomography (OCT) images were
captured before, immediately following and 3 hours after a short
period (3 hours) of miniscleral contact lens wear for 10 young
(mean 27±5 years), healthy participants. To allow comparison of
subsequent scans, OCT images from each measurement session,
for each participant, were aligned using custom written software by
identifying common anatomical landmarks in each scanning laser
ophthalmoscope en-face image (e.g. blood vessel bifurcations). To
compensate for any natural diurnal variations, OCT measurements
were repeated on a separate control day without contact lens wear
following the same experimental protocol.
Results: Following three hours of lens wear, statistically significant
conjunctival/scleral thinning was observed, with a mean decrease in
thickness of -24.16±3.6 μm (p<0.001), which diminished, but did
not return to baseline three hours after lens removal (-16.97±1.9 μm,
p<0.001). Tissue compression was observed across all quadrants,
with the greatest thinning observed superiorly (-49.99 ± 8.52 mm,
p<0.01). Averaged across all quadrants, the most thinning was
observed 2 mm posterior to the scleral spur (-48.22 ± 5.79 mm), the
approximate edge of the miniscleral landing zone. The global mean
tissue compression immediately following lens removal was not
associated with baseline scleral thickness (r=0.20, p=0.5) or apical
corneal lens clearance (r=0.43, p=0.21).
Conclusions: Optimal fitting miniscleral contact lenses cause
significant tissue compression in young healthy eyes, with the
greatest thinning observed superiorly, most likely due to the
additional force of the superior eyelid. These results partly explain
the clinical observations of reducing apical corneal clearance and lens
“settling” over the first few hours of miniscleral lens wear.
Commercial Relationships: Stephen J. Vincent, None; David
Alonso-Caneiro, None; Michael J. Collins, None
Multidimensional Scaling of Belmonte Esthesiometer Stimuli
Trefford L. Simpson1, Yunwei Feng1, Ping Situ2, Carolyn G. Begley2.
1
School of Optometry and Vision Science, University of Waterloo,
Waterloo, ON, Canada; 2School of Optometry, Indiana University,
Bloomington, IN.
Purpose: To determine the relationship between mechanical,
and chemical pneumatic stimulation of the cornea, using
multidimensional scaling (MDS).
Methods: Using an ascending method of limits, central corneal
thresholds in 9 normal subjects were measured with room- and
eye-temperature mechanical and chemical stimuli using computer
controlled Belmonte pneumatic esthesiometer. Warm & cool
mechanical and chemical stimuli at 1.5x or 2x threshold (8 stimulus
configurations in total) were then used for MDS. The similarities of
all pair-wise combinations of these 8 stimuli (28 in total) were rated
(in random order) on a continuous scale (0-100) “exactly the same”
to “completely different”. For example, subjects had to rate the
similarity of a cool mechanical stimulus, 1.5x threshold and a warmer
chemical stimulus, 2x threshold. Average and individual dissimilarity
matrices were analyzed using Smacof, Indscal and Proxscal in R and
SPSS.
Results: Scree plots showed that 2 dimensions were needed to
account for the dissimilarity data. Fig. 1 shows a 2 dimensional
solution with labels shaded using cluster analysis. The labels are c
or m (chem/mech) 15 or 2 (1.5x / 2x thresh) and 24 or 50 (room/eye
temp). The lower rightmost cluster includes all 4 chemical stimuli and
to the left are the 2 eye-temperature mechanical stimuli. The upper
rightmost stimuli are the coolest (room temperature mechanical) with
the eye-temperature stimuli lower and more leftward. Indscal weights
suggested that 1 subject’s ratings were dissimilar to the others.
Conclusions: This is the first integrated examination of whether the
stimuli produce the desired sensory effects based on the underlying
neurophysiology. Our results are not predicted by the physiology:
There appear to be primarily ‘discomfort’ (mechanical-chemical)
and thermal dimensions. This is surprisingly similar to the results
obtained when words for the sensory attributes of the ocular surface
were examined using MDS (ARVO 2012).
Commercial Relationships: Trefford L. Simpson, None; Yunwei
Feng, None; Ping Situ, None; Carolyn G. Begley, None
Support: NSERC Canada, National Eye Institute R01EY021794
Test-retest repeatability and calibration of a new automated
Belmonte esthesiometer
Ping Situ1, Trefford L. Simpson2, Carolyn G. Begley1. 1School of
Optometry, Indiana University Bloomington, Bloomington, IN;
2
School of Optometry and Vision Science, University of Waterloo,
Waterloo, ON, Canada.
Purpose: We have developed a custom, automated Belmonte
esthesiometer at Indiana University. The purpose of this study was
to calibrate the instrument and quantify repeatability of detection
thresholds measured with room temperature pneumatic stimuli.
Methods: The esthesiometer is a dual chamber mechanical, chemical
(CO2) and thermal pneumatic device. There is computer control
of flow, %CO2 and temperature and computerized collection of
subject responses. A temperature sensing circuit provides feedback
to maintain a steady stimulus temperature independent of air-flow
and ambient temperature. The output pressure and temperature
esthesiometer was calibrated using a flow sensor (HONEYWELL
AWM3100 V) and thermocouple (OMEGA type K). 15 non-lens
wearing subjects and 52 adapted lens wearers had pneumatic
detection thresholds estimated using an Ascending Methods of Limits
in 2 sessions with mean (± SD) interval 3.5 (± 2.1) days between
sessions. Each threshold was the average of the 3 flow rates at which
subjects first reported the stimulus. Data analysis was conducted
using R (3.1.2).
Results: After calibration, mean (± SD) test and retest thresholds
were 58.33 (± 20.6) and 58.85 (± 23.2) ml/min respectively. The
bivariate test-retest regression slope (ideal = 1.0) was 1.07 (95% CI
0.9-1.36) and the correlation coefficient of concordance was 0.74
(95% CI 0.61- 0.84). Bayesian mean test-retest difference was -0.057
(95% HDI -2.2 – 5.7 ml/min). Figure 1 shows the test-retest results
and some posterior estimates of the data.
Conclusions: The new design provides repeatable room temperature
threshold estimation. Calibration of the flow, temperature and CO2
content enable the measurement of the full range of ocular sensory
processing channel capabilities.
Baysian test-retest difference and some posterior estimates of the data
Commercial Relationships: Ping Situ, CooperVision Inc (F);
Trefford L. Simpson, CooperVision Inc (F); Carolyn G. Begley,
CooperVision Inc (F)
Support: National Eye Institute R01EY021794 (Begley) and a grant
from CooperVision Inc.
Design of peptide gels for bandage contact lenses
Rachel Williams1, Andrew Gallagher1, 2, Ahmed Elsheikh3, Don
Wellings2. 1Department of Eye and Vision Science, University of
Liverpool, Liverpool, United Kingdom; 2Speritech Ltd, Runcorn,
United Kingdom; 3School of Engineering, University of Liverpool,
Liverpool, United Kingdom.
Purpose: Corneal bandage lenses have an important role to play in
the treatment of corneal infection and disease. This laboratory study
aimed to develop novel peptide gels with appropriate mechanical
properties, transparency and water content for this application.
Methods: Peptide gels were synthesised from poly-ε-lysine (Pεk)
and cross-linked with dicarboxylic acids (hexanedioic acid (C6),
heptanedioic acid (C7), octanedioic acid (C8), nonanedioic acid
(C9) and decanedioic acid (C10)). The density of the Pεk was
between 0.07-0.1 g/ml and the crosslink density was 60% or 80%.
Ultimate tensile strength and elasticity was measured using a Linkam
Tensile Stress Tester. Water content was measured gravimetrically.
Transparency was measured using spectrophotometry at 544nm.
Cytotoxicity was measured using the HCE-T corneal epithelial cell
line and the CCK-8 assay. A scratch assay was used to evaluate
the re-epithelialisation under the peptide gels. Data were analysed
statistically with a one-way ANOVA with Tukey’s post-test analysis.
Results: The ultimate tensile strength increased with the Pεk
density, crosslink density and an increase in crosslinker molecular
chain length up until the hexanedioic acid (C9) and then reduced
for decanedioic acid (C10). The optimal gel composition to give the
highest mechanical properties without detrimentally affecting the
transparency had a Pεk density of 0.071 g/ml, suberic acid as the
crosslinker and a crosslink density of 60%. This produced a gel
(Su6014) with an elasticity of 0.50 ± 0.11 MPa (n=9), a transparency
of 90% ± 4.5% (n=9) and a water content of 69% ± 5.5% (n=9). This
gel showed no cytotoxicity in the CCK-8 assay with no statistically
significant differences in cell growth in normal culture medium and
medium after incubation with the gel for 3 days. Rate of wound
closure of the scratch assay was the same with or without the
presence of the gel.
Conclusions: The mechanical properties, transparency and water
content of a gel based on Pεk are comparable to commercially
available soft contact lenses and are non-cytotoxic and are thus
appropriate for further development as bandage contact lenses.
Commercial Relationships: Rachel Williams, Spheritech Ltd
(F); Andrew Gallagher, Spheritech Ltd (E); Ahmed Elsheikh,
Spheritech Ltd (F); Don Wellings, Spheritech Ltd (E)
Support: EPSRC Grant EP/M002209/1
Residual Hydrogen Peroxide after Neutralization of the Clear
Care® Lens Care System and a Novel Peroxide System
Huagang Chen, Tim Gibson, Kasey Minick, James Wu, Jessie Lemp.
Vision Care / R&D, Alcon Research Ltd, Arlington, TX.
Purpose: To asses residual hydrogen peroxide (H2O2) after
neutralization of two hydrogen peroxide lens care systems using both
in vitro and ex-vivo methods.
Methods: Five (5) AOCups/AODiscs per peroxide system (Clear
Care® and novel peroxide system) were tested at room temperature
through 100 cycles without a contact lens. Residual H2O2 of the
neutralized solution was measured via UV spectroscopy in parts per
million (ppm) after 1, 15, 30, 45, 60, 75, 90 and 100 cycles at 6 hour
neutralization. At each test interval, pH and osmolality were also
measured. Additionally, AOCups/AODiscs used with Clear Care®
to disinfect silicone hydrogel contact lenses for approximately 30
days were collected from 61 study subjects and analyzed for residual
H2O2.
Results: The mean residual H2O2 for both the Clear Care® system
and the novel peroxide system was below 5ppm after 100 cycles.
There was no significant difference in residual peroxide levels
between the two peroxide systems at any of the 8 test cycle intervals.
The mean pH of both systems ranged from 6.8 to 6.9 and the mean
osmolality ranged from 290-293 mOsm/kg at each test cycle up to
100 cycles. Residual H2O2 assay values from the AOCups/AODiscs
used with Clear Care® by study subjects for 30 days ranged from
6ppm to 55ppm with an average of 15±8ppm. Ninety-five percent
(95%) of the cases had residual peroxide below 30ppm after 30 days
of use.
Conclusions: Both the Clear Care® and the novel peroxide systems
are efficacious at neutralizing H2O2 down to below 5 ppm after 100
cycles. The Clear Care® system used by study subjects resulted in
slightly higher residual H2O2 concentrations, likely due to slight
deactivation of the disc by tear components introduced from worn
lenses. The majority of the 30-day patient used Clear Care® systems
neutralized H2O2 to a level of 30ppm or less, which is below the
level detectable by the ocular tissues.
Commercial Relationships: Huagang Chen, Alcon (E); Tim
Gibson, Alcon (E); Kasey Minick, Alcon (E); James Wu, Alcon (E);
Jessie Lemp, Alcon (E)
Support: Alcon sponsored research work
Lid Papillae Improvement with Use of a Hydrogen Peroxide Lens
Care Solution
Christopher Lievens1, Shane Kannarr2, Lisa Zoota3, Jessie Lemp3.
1
Southern College of Optometry, Memphis, TN; 2Kannarr Eye Care,
Pittsburg, KS; 3Alcon Research Ltd, Fort Worth, TX.
Purpose: To assess lid papillae and symptoms changes with use of
a hydrogen peroxide lens care solution for 3 months in symptomatic
contact lens wearers.
Methods: This randomized, controlled, investigator-masked,
parallel group, multi-site study enrolled symptomatic contact lenses
wearers presenting with at least mild lid papillae and habitually
using a biguanide-preserved multi-purpose solution (HMPS).
Eligible subjects were randomized to use their habitual solution or
Clear Care® (H202) for 3 months to care for their habitual lenses.
Symptoms (frequency 1-5 scale and intensity 0-5 scale) including
CLDEQ-8 (0-37 scale) were assessed and lid papillae was graded
with fluorescein at baseline and 3 months (0-4 scale in 3 upper lid
zones and 1 lower lid zone).
Results: 128 subjects completed the study at 12 U.S. sites. H202
users showed a significant improvement in lid papillae; mean
(95% CI) changes from baseline to Day 90 in maximum rated lid
papillae were 0.904 (0.744, 1.064) for CC and 0.423 (0.271, 0.576)
for HMPS (p<0.001). Additionally, both frequency and intensity
of symptoms were significantly less for H202 vs. HMPS users by
Day 90 (grittiness, end of day dryness, irritation, burning/stinging,
itchiness, and blurry vision; all p≤0.035). Mean CLDEQ-8 scores
after 3 months were significantly lower (better) for H202 (10.6±6.30)
vs. HMPS (15.0±7.29); p<.001.
Conclusions: The peroxide lens care solution was well-tolerated
by symptomatic contact lens wearers and is superior to biguanidepreserved MPSs at reducing lip papillae and contact lens wearing
symptoms when used for 90 days.
Commercial Relationships: Christopher Lievens, Alcon Research
Ltd. (F); Shane Kannarr, Alcon Research Ltd (F); Lisa Zoota,
Alcon Research Ltd. (E); Jessie Lemp, Alcon Research Ltd. (E)
Support: Alcon Research Ltd.
Patient Preferences between two multi-purpose disinfecting
solutions
Milton M. Hom1, I B. Gaddie2, Kirk L. Smick3. 1Private Practice,
Azusa, CA; 2Gaddie Eye Centers, Louisville, KY; 3Clayton Eye
Center, Morrow, GA.
Purpose: Two contact lens multi-purpose disninfecting solutions
were compared in a patient preference survey.
Methods: The study is randomized, investigator-masked, multicenter, prospective crossover study looking at contact lens solution
tolerability and performance. Patients were randomized into two
groups. Two groups are tested; Group 1: AMO’s RevitaLens (RVL)
then Alcon’s Opti-Free PureMoist (PM); Group 2: Alcon’s Opti-Free
PureMoist then AMO’s RevitaLens. Patients used each solution for
one to two weeks daily wear. Lenses worn were Biofinity. A patient
preference questionnaire was administered at the end of the study.
Results: 28 patients, mean age 35.29, age range: 18 to 61 years
old, 10 males: 18 females were seen at three sites. For Q1: Please
compare the overall comfort the CL solution provided after 2 weeks
of use: RVL was preferred 65.4%, PM 23.1% and equal 11.5%. For
Q2: Please compare the ability of the CL solution to effectively
provide symptom relief after 2 weeks of use: RVL was preferred
57.7%, PM 26.9% and Equal 15.4%. For Q3: Which CL solution
produced less blurring after 2 weeks of use:
RVL preferred 50%, PM 26.9% and Equal 23.1%. For Q4: Which CL
solution would you prefer to purchase on your own after 2 weeks of
use: RVL was preferred 69.2%, PM 26.9% and Equal 3.8%.
Conclusions: AMO’s RevitaLens was preferred over Alcon’s OptiFree PureMoist by the majority of patients at the end of the study.
Commercial Relationships: Milton M. Hom, AMO (F), Cooper
(C); I B. Gaddie, AMO (F); Kirk L. Smick, AMO (F)
Support: AMO research grant
Release of ciprofloxacin and moxifloxacin from daily disposable
contact lenses using an in vitro eye model
Magdalena Bajgrowicz1, Chau-Minh Phan2, Lakshman N.
Subbaraman2, Lyndon W. Jones2. 1Departement of Mechanics,
Materials Science and Engineering, Wroclaw Univeristy of
Technology, Wroclaw, Poland; 2Vision Science, University of
Waterloo, Waterloo, ON, Canada.
Purpose: To analyze the release of two fluoroquinolones,
ciprofloxacin and moxifloxacin, from conventional hydrogel (CH)
and silicone hydrogel (SH) daily disposable commercial contact
lenses (CLs) from a vial and an in vitro eye model.
Methods: Four CH CLs (nelfilcon A, omafilcon A, etafilcon
A, ocufilcon B) and three SH CLs (somofilcon A, narafilcon
A, delefilcon A) were incubated in a solution containing either
ciprofloxacin or moxifloxacin for 24 h. After the incubation period,
the lenses were placed in two release conditions: (1) a vial containing
4.8 mL of PBS for 24 hours and (2) an in vitro eye model with a PBS
flow rate at 4.8 mL over 24 h. The amount of drugs released was
determined using spectrophotometric technique.
Results: The release in the vial for both drugs was very rapid, and
reached a plateau between 15 min and 2 h for all lens types. In
contrast, under under physiological flow conditions, a constant and
slow release was observed over 24 h. The amounts of ciprofloxacin
released from the lenses ranged between 49.6±0.7 to 62.8±0.3 mg/
lens in the vial, and between 35.0±7.0 to 109.0±5.0 mg/lens in the eye
model. Moxifloxacin release ranged from 24.0±4.0 to 226.0±2.0 mg/
lens for the vial, and between 13.0±2.0 to 151.0±10.0 mg/lens in the
eye model. In both systems and for both drugs, HEMA-based CLs
released significantly more drug than other materials.
Conclusions: The parameters of the release system, in particular the
volume of the release medium and flow rate, have a huge influence on
release profiles. Under physiological flow conditions, release profiles
were significantly slower and constant when compared with release in
a vial model. The release is also affected by the material composition
of the lens, and the water solubility of the drug.
Commercial Relationships: Magdalena Bajgrowicz, None; ChauMinh Phan, None; Lakshman N. Subbaraman, None; Lyndon W.
Jones, None
Predictors for Misuse of Daily Disposable Lenses in a Large PostMarket Surveillance Registry – The TEMPO Registry
Robin L. Chalmers1, Sheila B. Hickson-Curran2, Lisa J. Keay3,
William Gleason4. 1Clinical Trial Consultant, Atlanta, GA;
2
Professional Development Department, Johnson & Johnson Vision
Care, Jacksonville, FL; 3Injury, George Institute for Global Health,
Sydney, NSW, Australia; 4none, Foresight Regulatory Strategies, Inc.,
Wilmington, MA.
Purpose: To describe predictors for overnight wear (EW) and
storage and reuse (re-use) of daily disposable (DD) lenses among
wearers of silicone hydrogel (SiHyDD) or hydrogel daily disposable
(HydDD) lenses in the 1•DAY ACUVUE® TruEye® (narafilcon B)
or 1•DAY ACUVUE® MOIST® (etafilcon A) Performance Overview
(TEMPO) Registry (#NCT01467557).
Methods: At registration, 977 habitual SCL wearers rated their
compliance with care of their SCLs and their eye care practitioners
(ECPs) also rated their compliance with instructions. Wearers
reported frequency of EW and reuse, key aspects of DD lens wear
at 2 wks, 4 mos and 12 mos via online surveys. A Wilcoxon Signed
Rank test compared the Likert scale rating of compliance between
the ECP and wearer. Reports of EW or re-use were modelled using
generalized estimating equations (GEE) with survey as a repeated
measure, adjusting for clustering by ECP site. The model included
age, gender, ECP and wearer rated compliance, and self-report of EW
with habitual SCLs.
Results: The Registry observed 977 habitual SCL wearers (801
(82%) for 12 mos) and included 240 (24.6%) who reported EW with
habitual lenses, usually for <1 day/week. There were no significant
differences between ECP and wearer ratings of overall compliance
with habitual SCLs (p=0.36, Wilcoxon Signed Rank test). EW with
DDs increased from 14% at 2 wks to 22% at 12 mos surveys (Odds
Ratio (OR) 1.52 (1.24, 1.87 95% CI) and re-use of DDs increased
from 9% at 2 wks to 17% at 12 mos surveys (OR 1.56 (1.32, 1.84).
Baseline ratings of overall compliance predicted later re-use of DDs:
ECP ratings (OR 1.56 (1.0, 2.4) p=0.05) and self-assessment (OR
1.72 (1.1, 2.6) p=0.01). EW of DDs was not predicted by baseline
ECP or wearer compliance ratings but was strongly predicted by
wearer report of EW with habitual SCLs at baseline (OR 9.7 (7.4,
12.7), p<0.0001).
Conclusions: During a year of remote follow-up in the TEMPO
Registry, EW and reuse of DD lenses both increased significantly
with longer time since refitting. Reuse of lenses was predicted by
self- and ECP assessment of overall compliance at baseline and
EW was strongly predicted by EW with habitual SCLs. Eye care
practitioners must re-train as they fit DDs to lens wearers to proper
use of DDs; no EW and no storage or re-use of lenses.
Commercial Relationships: Robin L. Chalmers, Alcon Research
Ltd (C), CooperVision Corp. (C), Johnson & Johnson Vision Care,
Inc (F); Sheila B. Hickson-Curran, Johnson & Johnson Vision
Care, Inc. (E); Lisa J. Keay, Johnson & Johnson Vison Care, Inc.
(C); William Gleason, CooperVision Corp. (F), Johnson & Johnson
Vision Care, Inc. (F)
Support: This study was supported by Johnson & Johnson Vision
Care, Inc.
Clinical Trial: #NCT01467557
Comparison of change in symptoms in contact lens wearers after
exposure to a low humidity environment
Katherine Bickle1, Jason J. Nichols2. 1The Ohio State University,
Columbus, OH; 2The University of Alabama at Birmingham,
Birmingham, AL.
Purpose: To evaluate the relation between dry eye status and change
in dry eye symptoms after exposure to a low humidity environment
(LHE).
Methods: Full time soft contact lens wearers were enrolled in a
one-visit study. The Contact Lens Dry Eye Questionnaire Short
Form classified subjects as normal or with contact lens discomfort
(CLD). Subjects completed pre-LHE measurements including
average non-invasive Keratograph break-up time (NIKBUT) on
the right eye while wearing habitual contact lenses. These same
measurements were performed post-exposure to the LHE. All
subjects were exposed to a LHE (4% humidity, 70-75°F, 0.5-1.5 m/s
air speed) for approximately 90 minutes. Subjects completed a PostHumidity Controlled Environment Survey and responded to changes
in symptoms of dryness, discomfort, and tearing. For dryness and
discomfort, possible responses were significantly better, better, no
difference, worse, or significantly worse after exposure to the LHE.
For statistical analysis, responses were grouped into two categories:
same or better (or worsening—e.g., more tearing) of symptoms. The
Chi-Square test was used for data analysis.
Results: Twenty-five normal (11 males, average age 27.9 ± 5.7 years)
and 25 CLD (8 males, average age 28.0 ± 9.8 years) subjects were
enrolled. Fourteen of 25 normal subjects reported no difference or
an improvement of dryness after exposure to a LHE compared to 7
CLD subjects. Eleven normal subjects reported worsening of dryness
compared to 18 CLD subjects (Chi-square statistic 4.0, p-value
0.04). After exposure to a LHE, 15 CLD subjects reported increased
discomfort compared to seven normal subjects (Chi-square statistic
5.2, p-value 0.02). Twelve subjects in both the CLD and normal
groups reported more tearing (Chi-square statistic 0.0, p-value 1.00).
Conclusions: Contact lens discomfort subjects were more likely
than normal subjects to report worsening of dryness and discomfort
after exposure to a LHE. However, there is no difference in reported
symptoms of tearing between the two groups after exposure to a
LHE.
Commercial Relationships: Katherine Bickle, None; Jason J.
Nichols, None
Post-marketing surveillance of overnight orthokeratology: 3-year
follow-up study in Japan
Takahiro Hiraoka, Yoshifumi Okamoto, Fumiki Okamoto, Tetsuro
Oshika. Department of Ophthalmology, Faculty of Medicine,
University of Tsukuba, Tsukuba, Japan.
Purpose: In April 2009, an overnight orthokeratology lens (α
Ortho®-K, Alpha Corporation) was first approved in Japan. The Japan
Ministry of Health obliged the company to do a post-marketing
surveillance (PMS) of the lens for 3 years. We herein report the
results of the PMS.
Methods: The data of 69 patients (136 eyes) enrolled in the PMS
were analyzed. The patients’ age was from 7 to 48 years old. Efficacy
of the lens was evaluated based on the analyses of changes in
refraction, visual acuity, intraocular pressure, corneal thickness and
corneal endothelium. Adverse events and drop-out cases were also
evaluated. Moreover, the results were compared between age ≥ 20
and age < 20 groups.
Results: Refraction and uncorrected visual acuity had changed
significantly after one day of lens wear. They further improved until
2 weeks, and remained stable thereafter. There were no significant
changes in IOP and endothelial cell density during the study period.
Adverse events were observed in 18 eyes; corneal staining in 10 eyes,
bulbar conjunctival hyperemia in 2 eyes, and superior tarsal papillary
hypertrophy in 2 eyes, etc.. All patients with adverse events resumed
the lens wear after healing each condition. Ten patients discontinued
myopic correction with orthokeratology and dropped out the PMS.
The reasons were “inconvenient at the time for work and driving”
(6 patients) and “inability to keep follow-up examinations due to
individual circumstances” (4 patients).
Conclusions: According to Japanese guidelines for orthokeratology,
it is recommend to apply orthokeratology lenses only to adults.
However, 54 percentages of the patients were less than 20 years
old. The results of PMS showed acceptable safety and efficacy
of α Ortho®-K, and no differences between the two age groups.
Appropriate prescription, sufficient education to patients, and
periodical follow-up examinations seem to minimize serious
problems in clinical practice of orthokeratology in both adults and
children.
Commercial Relationships: Takahiro Hiraoka, None; Yoshifumi
Okamoto, None; Fumiki Okamoto, None; Tetsuro Oshika, None
Corneal refractive power changes during orthokeratology using
different contact lens designs
Vinod K. Maseedupally, Pauline Kang, Mark Bae, Mikha Liem, Paul
Gifford, Helen A. Swarbrick. Sch of Optometry & Vision Science,
University of New South Wales, Sydney, NSW, Australia.
Purpose: To compare corneal refractive power (CRP) changes in the
horizontal and vertical meridians of the para-central region induced
by three orthokeratology (OK) lens designs worn overnight only for
2 weeks.
Methods: 19 myopic subjects (6M, 13 F, age: 21 to 41 years)
enrolled in this two phase prospective study. In phase 1, subjects
wore BE OK lenses (Capricornia Contact Lens, Australia) in both
eyes for 2 weeks. In phase 2, one eye was randomly chosen to wear
a Contex lens (Contex, USA) and the contralateral eye a Paragon
CRT lens (Paragon Vision Sciences, USA) for 2 weeks. Corneal
topography (Medmont E300, Australia) was obtained at baseline
and after 14 nights of lens wear in both phases. A custom written
MATLAB program was used to determine CRP along horizontal and
vertical meridians in 0.5mm increments from the vertex normal (VN)
up to 8mm diameter. Linear mixed model analysis was used to detect
differences between lens designs worn in the same eye in terms of
CRP change from baseline in the para-central region (annular region
from 2.5 to 3.5mm from VN) along each meridian.
Results: There was a significant difference in CRP change between
BE and Contex OK lenses along the horizontal meridian (p<0.001).
Analysis of individual locations revealed a reduced CRP at 2.5mm
nasal (p=0.002) and an increased CRP at 3.0mm (p<0.001) and
3.5mm (p=0.001) temporal with BE lenses. In the vertical meridian,
no difference was found in the overall CRP change in the paracentral region between the two lens designs (p=0.542). Comparisons
between BE and Paragon CRT lenses showed no significant
differences in CRP change between the lens designs in either
horizontal (p=0.329) or vertical (p=0.748) meridians. Averaging over
lens designs the reduction in central CRP (-1.9D) was greater than the
increase in para-central CRP (+0.4D).
Conclusions: Although significant differences were found in
CRP change between BE and Contex OK lenses at three locations
along the horizontal meridian, these differences were not clinically
significant. No significant differences were found between BE and
Paragon CRT lenses in either meridian. We conclude that the three
lens designs used in this study induce similar corneal refractive
effects. We did not find a 1:1 relationship between central reduction
and para-central increase in CRP as has been reported by others.
Commercial Relationships: Vinod K. Maseedupally, Bausch +
Lomb Boston (F), BE Enterprises Pty Ltd (F), Capricornia Contact
Lens Pty Ltd (F), Contex USA (R), Paragon Vision Sciences USA
(R); Pauline Kang, Bausch + Lomb Boston (F), BE Enterprises Pty
Ltd (F), Capricornia Contact Lens Pty Ltd (F), Contex USA (R),
Paragon Vision Sciences USA (R); Mark Bae, None; Mikha Liem,
None; Paul Gifford, None; Helen A. Swarbrick, Bausch + Lomb
Boston (F), BE Enterprises Pty Ltd (F), Capricornia Contact Lens Pty
Ltd (F), Contex USA (R), Paragon Vision Sciences USA (R)
Support: This research was funded through the Australian Research
Council Linkage Project Scheme.
Characterizing corneal changes induced by orthokeratology
using high resolution OCT: 1998 revisited
Pauline Kang, Merrilyn Lee, Lynn Lee, Helen A. Swarbrick. School
of Optometry & Vision Science, University of New South Wales,
Sydney, NSW, Australia.
Purpose: To confirm early research that used superseded
technologies, we re-investigated changes in epithelial and stromal
corneal thickness along the horizontal and vertical corneal meridians
after overnight OK lens wear using a high resolution Tomey CASIA
optical coherence tomographer (OCT).
Methods: 28 subjects (22.3 ± 1.9 years) were fitted with Paragon
CRT lenses (Paragon Vision Sciences Inc, USA) in both eyes and
wore lenses overnight only for 28 days. Visual acuity, objective
refraction (Shin-Nippon NVision-K 5001 autorefractor), corneal
topography (Medmont E300) and OCT scans (Tomey CASIA OCT)
were taken at baseline and after 28 days of OK. Repeated-measures
ANOVA, Friedman test and linear mixed model analysis with posthoc t-tests were used to analyse changes in visual acuity, refraction,
and epithelial and stromal corneal thickness. Analysis was limited to
right eye data.
Results: Spherical equivalent refraction significantly reduced from
-2.16 ± 1.06D to -0.27 ± 0.64D (p<0.001) after OK and there was
no change in best corrected visual acuity (p=0.794) over the lens
wear period. Corneal thickness reduced in the center and increased
in the mid-peripheral cornea after 28 days of lens wear. Specifically,
the epithelium significantly thinned at center (-19.1 ± 8.2μm) and
thickened at 3mm nasal (+3.1 ± 6.1μm) and 3mm inferior (+3.1 ±
7.2μm)(all p<0.05). Stromal thickness increased at center (+11.6 ±
10.0μm) and 3mm superior (7.7 ± 6.2μm)(all p<0.05).
Conclusions: Utilizing a high resolution OCT, significant changes
in central and mid-peripheral corneal thickness were measured along
the horizontal and vertical meridians after 28 days of OK. The study
confirmed earlier reports and demonstrated that central corneal
thinning is primarily epithelial and the increase in mid-peripheral
corneal thickness after OK is a combination of epithelial and stromal
tissue changes. Application of Munnerlyn’s formula indicates that
changes in corneal thickness account substantially for the central
refraction change measured after OK.
Commercial Relationships: Pauline Kang, Bausch + Lomb (F), BE
Enterprise (F), Capricornia Contact Lens (F); Merrilyn Lee, None;
Lynn Lee, None; Helen A. Swarbrick, Bausch + Lomb (F), BE
Enterprise (F), Capricornia Contact Lens (F)
Support: Australian Government ARC Linkage Scheme
Qualitative asymmetric mapping of lysozyme deposited on
various contact lens materials using confocal laser scanning
microscopy
Jaya Dantam1, Miriam Heynen1, Claudia Y. Dominici1, Lakshman
N. Subbaraman1, Chantal Coles-Brennan2, Zohra Fadli2, Lyndon W.
Jones1. 1Centre for Contact Lens Research, School of Optometry &
Vision Science, Waterloo, ON, Canada; 2Johnson & Johnson Vision
Care, Inc., Jacksonville, FL.
Purpose: Previous studies have demonstrated the uptake and
distribution of lysozyme in hydrogel contact lens (CL) materials
using the traditional vial incubation method. The purpose of this
study was to qualitatively assess the asymmetric uptake of lysozyme
by different CL materials using a confocal laser scanning microscopy
(CLSM) technique.
Methods: Six hydrogel CL materials belonging to various FDA
groups (group I: polymacon; group II: omafilcon A, nesofilcon
A, nelfilcon A; group IV: etafilcon A with Polyvinylpyrrolidone,
ocufilcon B) were incubated in an artificial tear solution comprising
fluorescently-labelled lysozyme for 16 h at 37°C. Appropriate
controls were included. During the incubation, a novel asymmetric
condition of lens exposure to ATS was simulated by blocking the
posterior surface of the CL with a custom made Teflon® mount.
After incubation, the central 5 mm of each CL was punched out and
mounted on a microscope slide. The uptake of lysozyme by different
CL materials was evaluated using CLSM with argon laser at 488nm.
CLs were optically sectioned every 2 mm intervals (z stack). The
fluorescence intensity profile of each CL sample was calculated with
ImageJ software, using the “Plot Z axis profile” module. The data
were normalized to plot the relative fluorescence for each CL profile.
Results: Mapping of asymmetric lysozyme distribution revealed
different patterns of lysozyme penetration into the CLs. All CLs
demonstrated the uptake of fluorescently-labelled lysozyme.
Polymacon (FDA group I) revealed a relatively higher concentration
of lysozyme within the bulk, while the group II materials showed a
homogeneous distribution of lysozyme from the anterior to posterior
surface. For the group IV materials, lysozyme was deposited at the
surface and bulk in a gradient pattern, with decreasing deposition
towards the posterior surface.
Conclusions: A novel model to demonstrate asymmetric uptake of
lysozyme by different CL materials has been developed. The location
of lysozyme in the bulk and on the surface varied across different
FDA CL groups. It is well established that etafilcon A CLs exhibit
high levels of lysozyme, and this study demonstrates that it is present
throughout the material and most of it is located in the bulk.
Commercial Relationships: Jaya Dantam, None; Miriam Heynen,
None; Claudia Y. Dominici, None; Lakshman N. Subbaraman,
Johnson & Johnson Vision Care, Inc. (F); Chantal Coles-Brennan,
Johnson & Johnson Vision Care, Inc. (E); Zohra Fadli, Johnson &
Johnson Vision Care, Inc. (E); Lyndon W. Jones, Johnson & Johnson
Vision Care, Inc. (F)
Support: This study was funded by Johnson & Johnson Vision Care,
Inc.
Purpose: To assess the safety and efficacy of a new non-invasive
bioimpedance prototype for the first time in human corneas under in
vivo conditions
Methods: Ten right eyes from ten healthy volunteers were included
in this pilot study. No contact lens (CL) use was allowed seven days
before the beginning of the study. A low-Dk CL (Dk=28) or a highDk CL (Dk=110) was randomly fitted in the right eye of each subject.
Epithelial and endothelial permeability were monitored throughout
the study: prior to CL wear (visit 1) and after three days (visit 2)
and one week (visit 3) of extended CL wear; using a bioimpedance
analysis system, which consists on the placement of a sensor on the
corneal surface to perform the measurements (Figure 1). Evaluation
of corneal health was carried out with a slit-lamp biomicroscope.
Central corneal thickness (CCT) and epithelial corneal thickness
(EPC) were monitored with the 3D OCT-2000
Results: The examination of the corneal surface occasionally
revealed slight, superficial punctuate keratopathy in the low-Dk
CL eyes, attributable to the wear of the CL. Subjects did not report
discomfort while performing the bioimpedance measurement. Eyes
fitted with low-Dk CL showed a statistically significant increase
(p=0.002 ANOVA with Bonferroni correction) in corneal swelling
over time (between visits 1, 2 and 3). After one week of CL use,
statistically significant differences (p=0.014 ANOVA) were found
for the epithelial swelling between high-Dk CL eyes and low-Dk CL
eyes. High-Dk and low-Dk CL eyes showed no statistical significant
differences over the study time (between visits 1, 2 and 3) in the
epithelial and endothelial permeability. No statistically significant
differences between eyes fitted with high-Dk and low-Dk CL were
found for epithelial permeability and endothelial permeability.
Results are summarized in Figure 2
Conclusions: This study provides for the first time a quantitative
assessment of the permeability of the epithelial and endothelial layers
of the human cornea in vivo based on bioimpedance measurements.
The method has been shown to be safe and effective in detecting
changes in the corneal permeability after CL wear. The results
presented may be refined by improving the repeatability and
reliability of the impedance system, and establishing the range for
normal values
Study of the corneal epithelial and endothelial permeability
in a contact lens human model using a new non-invasive
bioimpedance method
Ana Rio-Cristobal1, 2, Anton Guimera3, Estefania Traver4, Angela
Morejon1, 2, Carmen Herrero4, Rosa Villa3, Sven Jonuscheit6, 7, Raul
Martin1, 2, Miguel José Maldonado5, 2. 1Departamento de Física
Teórica, Atómica y Óptica, Universidad de Valladolid, Valladolid,
Spain, Valladolid, Spain; 2Instituto Universitario de Oftalmobiología
Aplicada (IOBA Eye Institute), Universidad de Valladolid, Valladolid,
Spain, Valladolid, Spain; 3Institut de Microelectrónica de Barcelona
IMB-CNM (CSIC), Bellaterra, Barcelona. Centro de Investigación
Biomédica en Red, Biomateriales y Nanomedicina (CIBER-BBN),
Zaragoza, Spain, Barcelona, Spain; 4Laboratorios SALVAT, S.A.
Esplugues de Llobregat, Barcelona, Spain, Barcelona, Spain;
5
Departamento de Cirugía, Oftalmología, Otorrinolaringología y
Fisioterapia, Universidad de Valladolid, Valladolid, Spain, Valladolid,
Spain; 6Vision Sciences, Dept. of Life Sciences, Glasgow Caledonian
University, Glasgow, United Kingdom, Glasgow, United Kingdom;
7
Institute for Applied Health Research, Glasgow Caledonian
University, Glasgow, United Kingdom, Glasgow, United Kingdom.
Corneal bioimpedance measurement
Results
Commercial Relationships: Ana Rio-Cristobal, None; Anton
Guimera, WO 2011/107645 A1 (P); Estefania Traver, Laboratorios
SALVAT, S.A. (E); Angela Morejon, None; Carmen Herrero,
Laboratorios SALVAT, S.A. (E); Rosa Villa, WO 2011/107645 A1
(P); Sven Jonuscheit, None; Raul Martin, None; Miguel José
Maldonado, WO 2011/107645 A1 (P)
Support: SAF2009-14724-C02-02
Clinical Trial: 419/12/EC
Foveal and Peripheral Defocus with Center-Distance and CenterNear Multifocal Contact Lenses on Myopic Eyes
Kelly E. Moore, David A. Berntsen. The Ocular Surface Institute,
University of Houston College of Optometry, Houston, TX.
Purpose: To determine the effect of center-distance and center-near
multifocal soft contact lenses on the horizontal peripheral defocus
profile of myopic eyes.
Methods: The right eye of 25 myopic subjects was fitted with a
Biofinity Multifocal D lens (center-distance design) and a Biofinity
Multifocal N lens (center-near design) with a +2.50 D add. Subjects
had a spherical equivalent contact lens correction between -1.00
D and -5.75 D. An open-field autorefractor was used to measure
refractive error centrally and at ±20°, ±30°, and ±40° from the
line of sight in the horizontal meridian with each lens on the eye.
Measurements were made while the subject looked at distance and
again at near (30 cm target). Lens order and measurement starting
location were randomized. A repeated-measures ANOVA was used to
determine the effect of contact lens type, retinal location, and viewing
distance on central and peripheral defocus. When appropriate,
adjusted post hoc t-tests were performed.
Results: The mean (±SD) age and central spherical equivalent
refractive error were 24.0±1.3 years and –3.45±1.42 D, respectively.
Differences in defocus with each lens type depended on the location
measured (p<0.0001), and the defocus experienced with each lens
type depended on the viewing distance (p=0.0002). With distance
viewing, the D lens caused a myopic shift in the far periphery (30°
and 40°) compared to the N lens ranging from -0.83 D to -1.92 D (all
p<0.05). With near viewing, mean foveal defocus (accommodative
lag) was slightly more hyperopic with the D lens (+0.86 D) than with
the N lens (+0.60 D). When looking at near, far peripheral defocus
(30° and 40°) was more myopic with the D lens than the N lens
(range: -0.55 D to -1.59 D; all p<0.05).
Conclusions: As expected, the center-distance multifocal resulted
in a myopic shift in the far periphery when looking at distance
compared to the center-near multifocal. The center-distance lens
resulted in more hyperopic foveal defocus than the center-near lens
when looking at near (as previously reported by others); however,
the center-distance lens had significantly less hyperopic defocus
in the periphery than the center-near design. Myopic defocus is
hypothesized to slow eye growth in children. Compared to the centernear lens, the center-distance design resulted in a myopic shift in
more retinal locations, despite a slight increase in foveal lag at near.
Commercial Relationships: Kelly E. Moore, None; David A.
Berntsen, None
Support: NIH T35-EY007088; NIH P30-EY07551
into a 2 mm radius of curvature probe and a flat 60 mm diameter
countersurface for incorporation into a pin-on-disk microtribometer.
The apparatus is then operated at discrete translational velocities
between 30 mm s-1 and 100 mm s-1 and the normal and friction forces
are recorded resulting in coefficient of friction data. Due to the
Gemini interface of the hydrogels, which typifies the interfaces in
the eye, results were significantly different from historical data found
when using glass as a surface or countersurface.
Results: Results showed that between 30 mm s-1 and 5 mm s-1
a speed-independent zone of low friction coefficient (m=0.01)
was found for both hydrogels. At speeds exceeding 5 mm s-1 the
coefficient of friction increased at a rate of ½ power. Rheological and
drag experiments were conducted to deduce the mechanisms affecting
lubricity. We believe that this transition is indicative of when the
polymer thermal fluctuations are able to relax local deformations
faster than new strains can be exerted on the countersurface,
hence denoted as polymer relaxation lubrication. As the material
properties of high water content hydrogels are dependent on thermal
fluctuations, the speed-independent regime is designated thermal
fluctuation lubrication.
Conclusions: These findings allow for a greater understanding of
all gel-like interfaces in the eye that are unlike classical lubrication
theories currently employed and understood in industry. Further
evaluation of these mechanisms can greatly support contact lens
design.
This work was funded by Alcon laboratories.
Speed-dependent lubricity of high water content hydrogels
Kyle Schulze1, Angela A. Pitenis1, Juan M. Uruena1, Ryan Nixon1,
Alison C. Dunn2, Thomas Angelini1, Wallace G. Sawyer1. 1Mechanical
and Aerospace Engineering, University of Florida, Gainesville,
FL; 2Mechanical Science and Engineering, University of Illinois at
Urbana-Champaign, Urbana, IL.
Purpose: Contact lens material is one of the parameters that is
often being modified during the design process in order to increase
comfort for the end-user. As such, the inclusion of high water
content hydrogels as surface gel layers in contact lenses is currently
being incorporated into lens design. In this work, we discover two
distinct lubricity regimes in several Gemini interfaces at a wide
range of ocular sliding speeds. These regimes are described by their
dominating mechanics: thermal fluctuation lubrication and polymer
relaxation lubrication. These results further elucidate the mechanisms
that affect lubricity in the eye and may aid in the continuing efforts of
contact lens design.
Methods: For these studies, two hydrogels of different chemistries
(n-isopropylacylamide and polyacrylamide) were each molded
dependent consumption of individual monomers, as well as formation
of PVP polymer. Gel Permeation Chromatography (GPC) was used to
measure the molecular weight distribution of iso-propanol (IPA) lens
extracts. FTIR, NMR, and ASAP high resolution mass spectrometry
were used to characterize fractions collected from GPC to
characterize the high molecular weight polymer. PVP concentration
of the IPA lens extracts was measured using a gas-phase pyrolysis
MS methodology. PVP content of bulk lens material was measured
using an off-line pyrolysis methodology.
Results: GPC analysis of IPA extracts of samfilcon A and senofilcon
A showed that a polymer on the order of >100KDa was extracted out
of each lens material. Characterization of GPC fractions with FTIR,
NMR, and MS showed that the high MW polymer was consistent
with PVP. Quantitation of PVP in bulk lens material showed that
the PVP content of samfilcon A was > 4X that of senofilcon A.
Quantitation of PVP in IPA lens extracts of fully processed lenses
showed that the PVP extracted out of samfilcon A lenses represented
only 10 % of the total PVP in the bulk of the lens. Therefore, the
majority of the PVP formed in-situ during lens curing remains in the
lens even after the harsh IPA extraction conditions.
Conclusions: The data presented supports the proposed dual phase
polymerization in the curing of samfilcon A lenses, which results in
the formation of high molecular weight PVP that is incorporated in
the lens matrix.
Commercial Relationships: Andrew Hoteling, Bausch and Lomb
(E); William Nichols, Bausch and Lomb (E); Harmon Patricia,
Bausch and Lomb (E); Conlon Shawn, Bausch and Lomb (E);
Daniel Hook, Bausch and Lomb (E); Ivan Nuñez, Bausch and
Lomb (E); Joseph Hoff, Bausch and Lomb (E); Orlando Cabarcos,
Bausch and Lomb (E)
Commercial Relationships: Kyle Schulze, Alcon Laboratories
(F); Angela A. Pitenis, Alcon Laboratories (F); Juan M. Uruena,
wgsawyer@ufl.edu (F); Ryan Nixon, Alcon Laboratories (F); Alison
C. Dunn, None; Thomas Angelini, Alcon Laboratories (F); Wallace
G. Sawyer, Alcon Laboratories (F)
Support: Alcon Laboratories
Characterization of Bulk PVP Content of samfilcon A Silicone
Hydrogel Lenses
Andrew Hoteling, William Nichols, Harmon Patricia, Conlon Shawn,
Daniel Hook, Ivan Nuñez, Joseph Hoff, Orlando Cabarcos. Bausch
and Lomb, Inc., Rochester, NY.
Purpose: A novel silicone hydrogel lens material, samfilcon A
was designed to polymerize in two time resolved phases with the
methacrylate based monomers polymerizing first followed by NVP
conversion to high molecular weight PVP. Several studies were
conducted using a range of analytical techniques to characterize and
quantitate the PVP content of samfilcon A.
Methods: The reaction of samfilcon A was monitored using
Photo Differential Scanning Calorimetry (Photo-DSC), Gas
Chromatography with a Flame Ionization Detector (GC-FID), and
high resolution/accurate mass (HR/AM) Liquid ChromatographyMass Spectrometry (LC-MS). GC-FID and LC-MS provided time
Polymerizable silicone compatibilizers for silicone hydrogels
Ananth V. Iyer, Aziza Sahin. RT&D, DSM, Berkeley, CA.
Purpose: Silicone hydrogels are important contact lens materials for
promoting corneal health by enabling higher oxygen permeability.
They, however, suffer from the drawback of having higher lipid
deposition than conventional hydrogels which can negatively
affect clarity and end of day comfort. A polymerizable zwitterionic
silicone (ZiSi) monomer was incorporated into silicone hydrogel
formulations to improve wettability and minimize the hydrophobic
domains with the intent of reducing lipid adsorption. The effect of
this zwitterionic silicone monomer in silicone hydrogel formulations
on clarity, oxygen permeability, equilibrium water content and size of
hydrophobic domains was investigated.
Methods: Silicone hydrogels were prepared using a formulation
containing 2-20 wt% zwitterionic silicone monomer (ZiSi),
3-[tris(trimethylsiloxy)silyl]propyl methacrylate (TRIS), and N,Ndimethylacrylamide (DMA) as monomers with 1.0 wt% crosslinker
(EGDMA) and 0.5 wt% thermal initiator azobisisobutyronitrile
(AIBN) followed by curing at 90°C for 1h. The oxygen permeability
of the silicone hydrogel films were measured on a MOCON
unit using a modified Coulometric method as referenced in ISO
18369-4:2006. Equilibrium water content (EWC) was determined
gravimetrically per the standard - ISO 18369-4:2006 Ophthalmic
Optics—Contact lenses—Part 4: Physicochemical properties of
contact lens materials. Clarity of hydrogel films are reported as a
qualitative comparison. Size of hydrophobic domain in hydrated
hydrogel films were characterized using a qualitative lipophilic dye
test as described in literature (Jacob, J. et al Visualizing hydrophobic
domains in silicone hydrogel lenses with Sudan IV. Invest
Ophthalmol Vis Sci. 2012;53(7):3473-3480). Relative staining was
determined by visual inspection.
Results: Table 1 below lists the Clarity, Dk, and EWC for
representative hydrogel films.
Conclusions: Silicone hydrogel films made with zwitterionic
silicone monomer have comparable oxygen permeability (Dk) and
equilibrium water content (EWC) while maintaining clarity and
mechanical stability to control films. The addition of zwitterionic
silicone monomer to the silicone hydrogel formulation did not seem
to have a detrimental effect on the silicone hydrogel properties, while
resisting any significant dye staining by the lipophilic dye used in this
study.
Commercial Relationships: Ananth V. Iyer, DSM (E); Aziza
Sahin, DSM (E)
Physico-chemical Evidence for A Confluent Hyaluronate Network
on the Surface of Silicone Hydrogel Lens Materials
Katarzyna A. Wygladacz, Daniel Hook. Vision Care, Bausch + Lomb,
Rochester, NY.
Purpose: To assess the attraction of hyaluronate (HA), present
in Biotrue MPS, to the surface of samfilcon A, senofilcon A, and
comfilcon A silicone hydrogels (SiHy). Chemical evidence for the
presence of the lubricant hyaluronate on SiHy surfaces was addressed
using X-ray Photoelectron Spectroscopy (XPS) characterization.
HA staining with Basic Red 2 coupled with detection by confocal,
differential interference contrast as well as phase contrast imaging
techniques was used to directly illustrate the hyaluronate network
across lens surfaces.
Methods: Lenses were soaked overnight with Biotrue MPS. All
samples were stained with Basic Red 2 stain for three minutes,
rinsed with DI water, and assembled on custom-made glass holders.
A polarized light Nikon Eclipse 2000 and an Olympus FV1000
confocal laser scanning microscope (CLSM) equipped with
differential interference contrast (DIC) attachment were used to
monitor hyaluronate distribution over silicone hydrogel surfaces.
Additionally, SiHy materials were incubated with a range of pure HA
concentrations 0.1 to 0.01 % (w/v) and exposed to the dye solution.
In addition, lenses soaked with the stain only but not exposed to
MPS or HA were characterized. All images were captured with 20X
microscope objective. When needed, confocal magnification was
applied to resolve the HA network details. The surface chemistry
of the lenses soaked in Biotrue MPS was examined for hydrated
samples by cold probe XPS.
Results: Microscopy imaging illustrated a homogenous, stained
hyaluronate network that covered the samfilcon A surface. The
morphology of HA transferred from Biotrue MPS was similar to
the HA-stain network recorded for control samples. Presence of
a uniform hyaluronate network on senofilcon A and comfilcon A
surfaces was also demonstrated. HA covered the examined lens
surfaces as demonstrated by cold probe XPS analysis.
Conclusions: Microscopy imaging by DIC, phase contrast, and
CLSM illustrated compatibly of the humectant hyaluronate with
samfilcon A, senofilcon A, and comfilcon A lenses. High molecular
weight HA present in Biotrue MPS partitioned on to the lens surface
and it was homogeneously distributed over all lens surfaces. The
morphology of the HA network adsorbed to samfilcon A, senofilcon
A, and comfilcon A soaked with Biotrue and lenses incubated with
pure hyaluronate solutions was similar.
Commercial Relationships: Katarzyna A. Wygladacz, Bausch +
Lomb (E); Daniel Hook, Bausch + Lomb (E)
Effect of chain length, formulation concentration, hydrophile
spacer and linear silicone structure of novel monomer on oxygen
permeability of contact lenses
Li Li, Scott Curtin, Rick Gallagher, Meredith Wiseman, Iris Hilker,
Michelle Seitz, Chunxia Sun. DSM, Berkeley, CA.
Purpose: Hydrophilic silicone monomers (SiO Monomer),
methacrylate-hydrophile-silicones with Si number 13, 9, 3, were
designed to use as ingredients for contact lenses. We investigated
the effect of silicone chain length and formulation composition on
oxygen permeability (Dk) of cured hydrogel films. In addition, Dk
of films were compared with films prepared using commercially
available silicone monomers, methacrylate PDMS, TRIS and
SIGMA. The influence of presence vs absence of hydrophile spacer
and bulky silicone vs. linear PDMS on Dk were studied.
Methods: We incorporated novel SiO Monomer 13, 9, 3,
methacrylate PDMS, TRIS and SIGMA in formulations with
hydrophilic monomer, DMA. The formulations consist of 0.8%
crosslinker, 0.2% photoinitiator and various amounts of silicone
monomer and DMA (2:1, 3:2, 1:1, 2:3, and 1:2). A modified
Mocon MH2/21 was used to measure the oxygen permeability by
coulometric method at 34°C.
Results: The Dk results are shown in Table 1.
Conclusions: Our results suggest that Dk increases with increasing
amount of silicone which is consistent with general trend observed
by the industry. Based on permeability model of Dk, the percolation
threshold for connectivity of the silicone phase is estimated to be
approximate 20% Si element. It was found that within class of linear
PDMS, hydrophile spacer between double bond and silicone chain
(methacrylate PDMS vs SiO monomer) and silicone chain length do
not appear to have much influence on Dk. In general, Dk from bulky
silicone materials are much lower than linear PDMS sources.
The results give guidance for how to achieve sufficient Dk by
controlling three principal material parameters: amount of silicone
component present, connectivity of silicone-containing phase, and
intrinsic permeability of silicone component.
© 2014 DSM. All rights reserved.
Commercial Relationships: Jessica Rex, Alcon Laboratories, Inc.
(F); Scott Perry, Alcon Laboratories, Inc. (F); Jessie Lemp, Alcon
Laboratories, Inc. (E); Cecile A. Maissa, Alcon Laboratories, Inc. (E)
Support: Alcon Laboratories, Inc.
Commercial Relationships: Li Li, DSM (E); Scott Curtin, DSM
(E); Rick Gallagher, DSM (E); Meredith Wiseman, DSM (E); Iris
Hilker, DSM (E); Michelle Seitz, DSM (E); Chunxia Sun, DSM (E)
Concentrations of Silicon at the Surface of Silicone Hydrogel
Contact Lenses
Jessica Rex1, Scott Perry1, Jessie Lemp2, Cecile A. Maissa2. 1Materials
Science and Engineering, University of Florida, Gainesville, FL;
2
Alcon, Alcon Laboratories, Inc., Fort Worth, TX.
Purpose: The surface composition and structure of materials are
known to directly influence interfacial properties. Furthermore,
composition and structure within the outermost atomic layers has
been observed to differ from that of the bulk material. To this end, the
concentration of the constituent elements in outermost 10.0 nm of the
surface of silicone hydrogel (SH) contact lenses was measured using
X-ray photoelectron spectroscopy (XPS).
Methods: Eleven SH lens types (balafilcon A, lotrafilcon A,
lotrafilcon B, senofilcon A, comfilcon A, samfilcon A, delefilcon
A, narafilcon A, stenfilcon A, somofilcon A daily disposable (DD)
and somofilcon A monthly) were prepared with a 24 hr soak in
a phosphate buffer solution before vacuum drying for analysis.
Integration of the photoelectron signals from all elements present and
normalization by published sensitivity factors allows the calculation
of % atomic concentration. By measuring photoelectron intensity as
a function of off angle (55-85°), the relative presence and distribution
of specific elements within the outermost 10.0 nm is captured.
Results: For all lenses, carbon, oxygen and nitrogen were observed
in varying quantities. In addition, fluorine was detected for comfilcon
A. The silicon content within the outermost surface region (10.0
nm) of the test lens materials varied substantially: balafilcon A
(7.7%), lotrafilcon A (1.2%), lotrafilcon B (1%), senofilcon A
(8.7%), comfilcon A (13.4%), samfilcon A (5%), delefilcon A (<1%),
narafilcon A (6.7%), stenfilcon A (7.9%), somofilcon A DD &
Monthly (8.8%).
Conclusions: Lenses differed most in their surface silicon
concentration, with delefilcon A and lotrafilcon A and B exhibiting
the lowest silicon contents within the outermost 10.0 nm of the lens
surface. Silicon has hydrophobic properties which, when found at the
surface, may influence the wettability of the contact lenses and their
interaction with the tear film and ocular tissues.
Compositional and Frictional Analysis of a Copolymer Solution
Treatment of Silicone Hydrogel Contact Lens Surfaces
Scott Perry1, Jessica Rex1, Alex Rudy1, Jennifer Lane2, Leroy
Muya2. 1Materials Science and Engineering, University of Florida,
Gainesville, FL; 2Vision Care Research, Alcon, Johns Creek, GA.
Purpose: The surface chemical compositions of three brands of
contact lenses were analyzed using X-ray photoelectron spectroscopy
(XPS) prior to and following treatment in a test solution of diblock
copolymer of polyethylene oxide and polybutylene oxide (nEO-BO).
Atomic force microscopy (AFM) was also employed to evaluate the
surface topography and frictional properties of these lenses prior to
and following similar solution treatments.
Methods: Three silicone hydrogel lens types (balafilcon A,
lotrafilcon B, and comfilcon A) were tested. Lenses were soaked for
a minimum of 8 hours in nEO-BO hydrogen peroxide solution (3%
peroxide) in AOSept lens cases. For surface compositional analysis
with XPS, lenses have been prepared through a vacuum drying
procedure, in which the hydrogel is taken from a fully hydrated state
directly to an ultraclean, ultrahigh vacuum environment. Colloidal
probe AFM was used to measure the frictional properties of the
treated lens surfaces in aqueous environments.
Results: Prior to treatment, differences in surface elemental
composition of the various lenses were found to reflect known
bulk compositions and/or respective surface treatments. Following
solution treatment, photoelectron intensity attributable to the uptake
of the block copolymer on the surface was apparent for balafilcon
A (19.4±9.5%) and lotrafilcon B (38.5±27.2). Only modest changes
in surface composition were observed for comfilcon A. AFM
measurements in saline revealed large disparities in the impact of
copolymer adsorption on the coefficients of friction, with balafilcon
A (85% reduction) and lotrafilcon B (82% reduction) exhibiting
the largest changes. In contrast, only small changes in friction
attributable to copolymer uptake were observed for comfilcon A.
Conclusions: Together, these results depict a correlation between the
lens surface composition and the impact of polymer adsorption on the
frictional response of silicone hydrogel lenses. The results indicate
this specific diblock copolymer consisting of polyethylene oxide and
polybutylene oxide can have a positive impact on the lubrication
properties of certain silicone hydrogel lenses.
Commercial Relationships: Scott Perry, Alcon Vision Care
Research (F); Jessica Rex, Alcon Vision Care Research (F); Alex
Rudy, Alcon Vision Care Research (F); Jennifer Lane, Alcon Vision
Care Resarch (E); Leroy Muya, Alcon Vision Care Resarch (E)
Support: Alcon Vision Care Research
How close are current contact lens products to ideal
performance?
Percy Lazon De La Jara1, 2, Brien A. Holden1, 2, Thomas Naduvilath1,
Eric B. Papas1, 3. 1Brien Holden Vision Institute, The Ponds, NSW,
Australia; 2School of Optometry and Vision Science, University of
New South Wales, Sydney, NSW, Australia; 3Vision Cooperative
Research Centre, Sydney, NSW, Australia.
Purpose: To evaluate how closely contemporary contact lens
performance approaches the ideal of no lens wear in terms of ocular
adverse events (AEs) and subjective responses.
Methods: Retrospective analysis of data (n=1945) from 45 clinical
trials, each with a different wearing modality (39 contact lens/
solution daily wear [DW] combinations, 6 daily disposable [DD]
contact lenses and one group of emmetropic (non-contact lens
wearers) was conducted. All trials lasted for 3 months and were
carried out under the same protocol where approximately 40
participants wore their assigned contact lens on a daily wear basis.
14 different lens types and 8 solution types were included in the
study. Physiological and subjective responses were collected at
regular intervals. Data were converted into a ratio between 0 and 1
to represent the relative performance within the series, with a higher
ratio indicating better performance. Confidence limits of the AE
rates and end of day comfort (EODC) scores from emmetropes, were
used to establish the boundary criteria for acceptable no-lens wear
performance.
Results: No-lens performance equivalence boundaries were defined
at a minimum ratio of 0.77 for both AE and EODC. One DW
combination and 1 DD contact lens met the standard for both AE and
EODC. The results for ninety six percent of the modalities studied
performed below the non-lens wear equivalence criteria for any AE
and EODC. Despite, daily disposables performing well for AE (ratio
range: 0.80 to 1.00), their EODCs were not consistently high (ratio
range: 0.10 to 0.79). Insertion comfort ratios correlated positively
with both EODC (r=0.7, p<0.001) and Solution Induced Corneal
Staining ratios (r=0.42, p<0.01).
Conclusions: The performance of only a small proportion of current
contact lens systems approximates that of no-lens wear, in terms
of AEs and EODC. Favourable AE performance is not necessarily
accompanied by high comfort ratings.
Commercial Relationships: Percy Lazon De La Jara, None; Brien
A. Holden, None; Thomas Naduvilath, CIBA Vision (P); Eric B.
Papas, CIBA Vision (P)
Clinical Trial: ACTRN12611000939998
Designing a Photo-Responsive Contact Lens
Farah Shareef1, David Szlachta1, Genesis Contreras1, Andrew
Chen1, Dimitri T. Azar2, Michael Cho1. 1Bioengineering, University
of Illinois at Chicago, Lombard, IL; 2Ophthalmology, University of
Illinois at Chicago, Chicago, IL.
Purpose: Excessive light exposure associated with diminished
iris functionality leads to photophobia, glare, and poor vision in
patients with congenital or trauma induced iris damage. Commercial
artificial irises provide aesthetics by reconstructing the iris shape and
color without restoring iris functionality. A new photo-responsive
contact lens that mimics the natural iris’s dynamic response to
light was developed using DEA, a photochromic material, within a
biocompatible polymer matrix. Activated by blue light, DEA changes
its opacity to reduce light transmission to the eye.
Methods: DEA powder dissolved in acetone was combined with
polydimethylsiloxane (PDMS, Sylgard 184, Sigma) and underwent
a 4-day wash cycle to form the photochromic contact lens. Optical
properties including the kinetics of activation and reversal, and
percent light attenuation were measured using a DU 530 UV/Vis
Spectrophotometer for wavelengths 300-700nm. In vitro cell toxicity
testing was conducted for up to 1 month. A live/dead viability assay
and confocal microscope were used to stain and image the cells.
Potential leaching of DEA from the contact lens was quantified by
comparing wash cycle water to water with known amounts of DEA.
Results: Photochromic contact lens were created with 0.025 to
0.4 weight percent DEA uniformly distributed in PDMS. Optical
testing indicated reversible activation in 1 second. Wavelength scans
showed graded attenuation of up to 40% of UV and visible light.
Quantification of live cells demonstrated 90% cell viability with
no significant change in morphology or proliferation rate between
control cells and those exposed to our contact lens. Degradation
studies revealed leaching of less than 0.5% DEA.
Conclusions: A novel design for our photochromic contact lens
was achieved by integrating DEA within a PDMS polymer matrix.
Rapid and reversible activation by blue light allows the contact
lens to control light entering the eye and thus alleviate the adverse
symptoms of decreased iris function. Cell culture experimentation
demonstrated biocompatibility. Subsequent testing showed minimal
DEA leaching, which corroborated these findings. By mimicking the
natural iris functionality, our photochromic contact lens may provide
an improved treatment option for patients with iris damage.
Commercial Relationships: Farah Shareef, None; David Szlachta,
None; Genesis Contreras, None; Andrew Chen, None; Dimitri T.
Azar, None; Michael Cho, None
Scleral Contact Lens Effects on Central and Peripheral Corneal
Thickness
William L. Miller, Kelsea Vance, Leah Johnson, Jan P. Bergmanson.
College of Optometry, University of Houston, Houston, TX.
Purpose: Scleral contact lenses are an essential mode of correcting
corneal abnormalities as a result of keratconus and corneal surgery.
New generations of lenses have focused on design features that
allow vaulting the irregular corneal surface and navigating limbal
and scleral anatomy. Recently, research has addressed the theoretical
physiological requirements needed for oxygen transmissability that
takes into account Dk/t of scleral lens and tear film. The purpose of
the present study was to determine the effect of scleral contact lenses
on corneal physiology.
Methods: Corneal thickness of 24 eyes of 16 patients seen in a
scleral lens predominant practice in the TERTC of the University of
Houston were analyzed. Each patient had been wearing the scleral
contact lens for at least 2 weeks. Each scleral lens prescribed was
shown to have an acceptable fit by the contact lens practitioner with
no areas of impingement or conjunctival blanching. The age range
from 26 to 70 years of age with 10 males and 6 females included for
analysis. The corneal thickness of the central, peripheral and apical
regions were measured before being fitted with scleral contact lenses
with a Pentacam tomographer.
Results: The mean pupillary corneal thickness pre-lens wear was
502+/- 9.3 microns and after lens wear was 507+/- 8.8 microns.
Apical corneal thickness before and after lens wear was 485+/- 11.2
and 484+/- 12.5 microns respectively. The inferior corneal thickness
was 638+/- 27.7 and 643+/-18.0 microns before and after scleral
lens wear. Corneal thickenss in the superior region of the cornea was
640+/- 9.4 and 658+/- 9.7 microns before and after scleral lens wear.
Corneal volume was 57 prior to lens wear and 59 after lens wear.
Conclusions: Results indicated that the central, apical and inferior
peripheral corneal thickness were not statistically different before
and after scleral contact lens wear. The superior corneal thickness
was increased but was not statistically significant. This clinical
study showed no significant corneal swelling in a small group of
patients satisfactorily fitted in a scleral contact lens. Assuming an
adequate fitting and without excessive corneal vault, scleral lenses
do not appear to cause significant corneal swelling. Other factors
not observed in this patient population such as low endothelial cell
density and poor tear exchange may induce corneal swelling.
Commercial Relationships: William L. Miller, None; Kelsea
Vance, None; Leah Johnson, None; Jan P. Bergmanson, None
Corneal cell morphology in keratoconus patients wearing
different types of contact lenses for 6 months – a confocal
microscopy observation
Somnath Ghosh, Haliza Abdul Mutalib, Sharanjeet Kaur, Rituparna
Ghoshal. Optometry and Vision Sciences, University Kebangsaan
Malaysia, Shah Alam, Malaysia.
Purpose: Visual rehabilitation in keratoconus is best done with
contact lenses (CLS) that vary extensively in designs and parameters.
However, it has not been well established that changes in corneal
morphology in keratoconus depend on type of contact lens (CL) used.
A longitudinal, randomised clinical study was performed to compare
the changes in corneal cell morphology after 6 months of CL wear
with baseline observation in keratoconus patients wearing different
types of CLS.
Methods: Twenty eyes of 14 patients aged between 18 to 50 years
with stage 1 to 3 (Amsler–Krumeich, 2006) keratoconus were
included. Ten eyes were fitted with regular RGP (RRGP) and rests
were fitted with specially designed RGP (SRGP). A single patient
was fitted with a mini-scleral CL. Corneal cell morphology was
evaluated using a slit scanning confocal microscope at base line and
after 6 months of CL wear. A semi-automated method using “NAVIS”
software was employed to calculate cell area and density of corneal
layers in a fixed frame of 0.06 mm2.
Results: After six months of CL wear, the mean anterior (844.70
± 37.59) and posterior (677.51 ± 38.94) stromal keratocyte density
were significantly less (p=0.000 & 0.017) compared to baseline
observation (891.27 ± 45.21 &714.20 ± 45.43 respectively) in RRGP
group. Mean area of anterior and posterior stromal keratocyte were
also significantly different (p=0.001 & 0.021) from baseline. Changes
observed in endothelium were not statistically significant. Level of
corneal haze increased in 60% patients in this group.
For the SRGP group, statistically significant changes were observed
only in anterior stroma (p= 0.002 & 0.017 for cell density & area
respectively) after 6 months. Increase in corneal haze was observed
only in 50% patients. Patient, wearing mini-scleral demonstrated
noticeable qualitative and quantitative morphological alterations after
6 months.
Conclusions: Degree of morphological alterations in keratoconic
corneas may vary depending on the CL used. SRGP lenses made
fewer changes in corneal morphology compared to RRGP lenses after
6 months of CL use. However, increase sample may further assist in
understanding the cellular changes in keratoconus with mini-scleral
CLS.
Elongated keratocyte nuclei in a keratoconic eye with regular RGP
Stromal black vertical llines in a keratoconic eye with mini-scleral
contact lens
Commercial Relationships: Somnath Ghosh, None; Haliza Abdul
Mutalib, None; Sharanjeet Kaur, None; Rituparna Ghoshal, None
Novel in vitro method to determine pre-lens tear break up time of
hydrogel and silicone hydrogel contact lenses
Hendrik Walther, Lakshman N. Subbaraman, Lyndon W. Jones.
CCLR, School of Optometry and Vision Science, University of
Waterloo, Waterloo, ON, Canada.
Purpose: To develop a novel, in vitro model to determine pre-lens
non-invasive tear breakup time (NIBUT) and to compare the NIBUT
values of different daily disposable (DD) contact lenses (CLs) using
this model.
Methods: Three silicone hydrogel (SH) (delefilcon A, somofilcon
A, narafilcon B) and two conventional hydrogel (CH) (etafilcon A,
nesofilcon A) DD lens materials were incubated in an artificial tear
solution (ATS) containing a variety of proteins and lipids. A model
blink cell (MBC) was utilized, in which the CLs were submerged
in the ATS for 3 seconds (s) and exposed to air for 10 s, to mimic
intermittent air exposure. CLs were taken out of the blister pack
and the initial (T0) NIBUT was measured. Thereafter, breakup times
(n=4) of the CLs were determined after 2, 6, 12, and 16 hours (h) of
incubation. A corneal topographer (CA-100, Topcon Canada) was
used to illuminate the lens surfaces and changes of the placido ring
image on the lens surfaces were captured with a digital video camera
(Canon-XA10).
Results: Overall, NIBUTs ranged from 26.19 ± 5.79 s to 1.23 ± 0.13
s. When comparison was made between lens types (all time points
pooled), nesofilcon A showed the longest NIBUT (p<0.001). At T0,
CH CLs revealed significantly longer NIBUT (p≤0.001) than SH
CLs. After 2 h, nesofilcon A showed the longest NIBUT, however,
this was only statistically significant over delefilcon A (p≤0.001).
After 6 h, nesofilcon A was significantly longer than all other CLs
(p≤0.001). Etafilcon A showed a significantly superior NIBUT of 6.13
± 0.36 s (p≤0.001) over all other CLs after 12 h. With a NIBUT of 3.6
± 0.26 s, delefilcon A had the longest breakup time (p≤0.001) after 16
h of incubation, when compared to other CLs. Statistically significant
(p≤0.05) changes of NIBUT within the lens materials varied between
the examined time points. NIBUT decreased significantly (p≤0.002)
between T0 and 2 h for all CLs, except for somofilcon A (p=0.728).
NIBUT between T0 and 16 h was significantly lower for all CLs
(p≤0.001).
Conclusions: A novel in vitro model has been developed which could
be used to determine pre-lens NIBUT values. By using a MBC for
lens incubation and by incorporating intermittent air exposure, it is
possible to mimic CL wear, in vitro. NIBUT reduced gradually over
time and varying levels of deposition on different CLs seem to impact
the measured pre-lens NIBUT of various lens materials.
Commercial Relationships: Hendrik Walther, None; Lakshman
N. Subbaraman, None; Lyndon W. Jones, None
Tear film parameters and contact lens discomfort
Dorota H. Szczesna-Iskander, Paulina Jamiol, Malgorzata Biazik,
Angelika Ogar. Department of Optics and Photonics, Wroclaw
University of Technology, Wroclaw, Poland.
Purpose: To investigate the correspondence of Tear film Surface
Quality (TFSQ) and Stability (TFSS) assessed in vivo using
interferometry and videokeratoscopy, with contact lens discomfort
(CLD), standard anterior eye examination observation and tear film
osmolarity.
Methods: Non-invasive dynamic High-Speed Videokeratoscopy
(HSV) and Lateral Shearing Interferometry (LSI), tear film
osmolarity (TearLab), fluorescein tear break-up times (FBUT),
tear meniscus height (TMH) – slit lamp graticule and OCT based),
fluorescein and lissamine-green staining, and lid wiper epitheliopathy
were measured on 14 experienced contact lens wearers with normal
tear film (TF) fitted with daily disposable silicone-hydrogel lens
(SHL) and hydrogel lens (HL) (average age 23±4 years, 11F/3M).
Symptoms were evaluated by the Ocular Surface Disease Index
(OSDI) and Contact Lens Dry Eye Questionnaire (CLDEQ-8).
After two weeks daily (11.8±1.8 h per day) contact lens wear the
above metrics were re-measured for each pair of lenses. One week
of washout between lenses was applied. For evaluation of contact
lens materials the group median of each parameter was calculated.
The statistical analyses included standard descriptive statistics and
a nonparametric one way ANOVA (Kruskal-Wallis). Correlation
analysis was used to assess links between objective measures and
subjective comfort.
Results: HL material worsened TFSQ and TFSS less than SHL in
respect to pre-corneal TF. Significant differences in average TFSQ
and TFSS were noticed between lens materials on the first day of
wear (p=0.008), but not two weeks after (p=0.16). SHL resulted
in significantly higher staining score of conjunctival regions than
HL (p=0.02). SHL was evaluated as more comfortable than HL by
the majority of subjects. In 7 cases changes in tarsal conjunctiva or
Marx line were observed. Correspondingly, in 5 cases worsening of
TFSQ occurred. No statistically significant correlation between TF
osmolarity, TMH, TFSQ, TFSS, and CLD was found.
Conclusions: Although LSI and HSV techniques have the ability
to distinguish between lens materials in vivo, in this pilot study no
correspondence between the subjective comfort and TFSQ and TFSS
assessed by those methods was shown for contact lens wearers.
Further studies involving larger group of subjects and longer time of
lens wear are needed to confirm lack of those associations.
Commercial Relationships: Dorota H. Szczesna-Iskander, None;
Paulina Jamiol, None; Malgorzata Biazik, None; Angelika Ogar,
None
Support: POMOST/2012-5/8/0072
Impact of time of day and length of wear on contact lens
discomfort
Nancy J. Keir1, Sruthi Srinivasan2, William Ngo2, Paul Chamberlain1,
Wenjuan Feng1, Lyndon W. Jones2, John J. McNally1. 1R&D,
CooperVision, Pleasanton, CA; 2Center for Contact Lens Research,
School of Optometry and Vision Science, Waterloo, ON, Canada.
Purpose: To evaluate the impact of time of day and length of wear on
contact lens (CL) comfort in subjects who are asymptomatic (ASYM)
and symptomatic (SYM) for end of day CL discomfort.
Methods: 24 adapted soft CL wearers were enrolled (10 ASYM and
14 SYM). Classification was according to intensity and frequency of
late day dryness [Young et al. 2011] and the difference between total
and comfortable wearing time (≤ 2hrs for ASYM; ≥ 3hrs for SYM).
Biofinity CLs were worn bilaterally for six cycles. Cycles 1 and 2
included 12 hours of spectacle and CL wear, respectively. Cycles 3-6
included 3hrs of lens wear at different times of the day (8am-11am,
11am-2pm, 2pm-5pm and 5pm-8pm, respectively). Cycles were
completed in random order on separate days. In all cycles comfort
was rated hourly using a 0-100 visual analogue scale.
Results: The ASYM group had minimal change in comfort
with spectacles or CLs over the 12-hour cycle (4±8 and 13±16,
respectively, both p>0.05). Comfort in the ASYM group did not
reduce significantly over any 3-hour wearing period in cycles 3-6
(2±6, 3±5, 4±5 and 4±6, respectively, all p>0.05). Comfort declined
significantly in the SYM group with CLs over the 12-hour cycle
(32±21, p<0.01), but not with spectacles (6±15, p>0.05). The change
in comfort for the SYM group during cycles 3-6 was 2±9, 8±15,
14±13 and 14±15 and was statistically significant for cycles 4-6
(p<0.05). The decline in comfort with 12hrs of wear was greater
than the maximal change over 3hrs (32±21 vs. 14±15, respectively,
p<0.05).
Conclusions: In this study comfort was negatively impacted by both
time of day and length of wear in subjects who were SYM for end of
day CL discomfort.
Commercial Relationships: Nancy J. Keir, CooperVision (E);
Sruthi Srinivasan, CooperVision (F); William Ngo, CooperVision
(F); Paul Chamberlain, CooperVision (E); Wenjuan Feng,
CooperVision (E); Lyndon W. Jones, CooperVision (F); John J.
McNally, CooperVision (E)
Support: CooperVision
A Low and High Humidity Controlled Environmental Exposure
Model (EEC) Model: A Highly Specific and Sensitive Model to
Measure In Vivo CL dehydration
Holly I. Lorentz1, Stephanie Recker1, Chuck Shi2, James J. Mun2,
Anne Marie Salapatek1, Fiona Soong1. 1Inflamax Research Inc,
Mississauga, ON, Canada; 2CooperVision, Pleasanton, CA.
Purpose: An investigational, proof of concept study, to evaluate the
impact of low and high controlled humidity environments on contact
lens (CL) dehydration.
Methods: 10 non-symptomatic adapted CL wearers were screened
and randomized to a treatment sequence of two different CL materials
(etafilcon A [ETA] and senofilcon A [SEN]) worn at four EEC visits
in which the environmental conditions were set to either 10±3% RH
or 50±5% RH, an air flow of 2-5ft/sec and a temperature of 23±3°C.
Prior to entering the EEC, randomized CLs were worn briefly (<1
min) by the subjects and then removed so their baseline wet weight
could be measured using gravimetry. A new pair of randomized
CLs was then inserted prior to the subjects entering the EEC for
150min to visually task on a digital screen. Upon exit from the EEC,
all worn CLs were removed directly from the eye and their postEEC wet weight measured via gravimetry. Following wet weight
measurements, CLs were fully dehydrated and dry weight measured.
CL water content determined according to ISO standards.
Results: ANCOVA analysis of the main variables, revealed
statistically significant differences (p<0.002) in MCFB CL water
content when lenses were worn in the EEC under RH10% when
compared to RH50%. Similarly, statistically significant differences
between SEN and ETA MCFB CL water content were also found
in the EEC (p<0.002). When looking at the individual treatment
regimens in the ANCOVA analysis, the greatest MCFB decreases in
water content were seen for ETA RH10% (LSMeans -4.90%±0.23%)
when compared to ETA RH50% (LSMeans -3.08%±0.23%),
p<0.0001. Statistical differences in LSMeans were also seen between
10%RH ETA and 10%RH SEN (p=0.047) and between 50%RH ETA
and 50% SEN (p=0.001).
Conclusions: In vivo contact lens dehydration can be examined in
the controlled humidity EEC model; the low humidity EEC elicits
more CL dehydration than high humidity EEC conditions, especially
for ETA. In this small sample, the controlled humidity EEC model
was able to detect small differences in water content between
different lens materials as well as in different humidity conditions
using the ANCOVA model.
Commercial Relationships: Holly I. Lorentz, Inflamax Research
Inc. (E); Stephanie Recker, Inflamax Research Inc. (E); Chuck
Shi, None; James J. Mun, None; Anne Marie Salapatek, Inflamax
Research Inc. (E); Fiona Soong, Inflamax Research Inc. (C)
Selective uptake of lysozyme by various hydrogel contact lens
materials
Negar Babaei Omali1, Lakshman N. Subbaraman1, Chantal ColesBrennan2, Zohra Fadli2, Lyndon W. Jones1. 1Optometry and Vision
Sciences, Centre for Contact Lens Research, Waterloo, ON, Canada;
2
Johnson and Johnson Vision Care, Jacksonville, FL.
Purpose: Contact lenses have been shown to deposit tear film
components within hours of wear which may be a contributing factor
to clinical performance. Lysozyme is a beneficial protein in the tear
film and is part of the eye’s innate defense mechanism. The goal of
this work was to evaluate the selective uptake of lysozyme compared
to other tear proteins by hydrogel contact lens materials after
exposure to an artificial tear solution (ATS).
Methods: Six hydrogel CL materials (etafilcon A with
polyvinylpyrrolidone (PVP), polymacon, nelfilcon A, omafilcon A,
ocufilcon B and nesofilcon A) were evaluated, wherein one set of
lenses was soaked in an ATS to determine total protein uptake and
another set was soaked in an ATS containing 125I-labeled lysozyme,
lactoferrin or albumin to specifically measure the individual three
proteins. Both sets of lenses were incubated for 16 h at 37°C. Lenses
incubated in ATS were extracted using a solution containing 0.2%
trifluroacetic acid in 50/50 water: acetonitrile solution and total
protein uptake was determined using a standard Bradford assay.
Lenses soaked in radiolabeled proteins were rinsed in phosphate
buffered saline and radioactive counts were measured directly on
lenses using a Gamma Counter. Individual protein uptake on lenses
was measured using calibration curve plotting radioactive counts
versus protein concentration.
Results: Etafilcon A deposited the highest amount of total protein
(568.3±45.4 mg/lens) with the majority represented by lysozyme
(94%) (p<0.0001). The amount of total protein deposited on ocufilcon
B was of 206.6±42.2 mg/lens with 96% of the uptake represented
by lysozyme. The amount of lysozyme deposited on omafilcon A,
nesofilcon A, nelfilcon A and polymacon was less than 20 μg/lens.
When compared to lactoferrin and albumin, significantly higher
levels of lysozyme deposited on etafilcon A, ocufilcon B, nesofilcon
A and omafilcon A materials (all p=0.0001).
Conclusions: The quantity and nature of proteins deposited on
CLs varies depending upon the chemical composition of the lens
material. Among the various lenses tested, etafilcon A deposited the
highest amount of total protein, most of it represented by lysozyme,
a beneficial protein present in the tear film. Further investigation is
needed to understand whether this is a contributing factor to clinical
performance.
Commercial Relationships: Negar Babaei Omali, None;
Lakshman N. Subbaraman, Johnson and Johnson Vision Care (F);
Chantal Coles-Brennan, Johnson and Johnson Vision Care (E);
Zohra Fadli, Johnson and Johnson Vision Care (E); Lyndon W.
Jones, Johnson and Johnson Vision Care (F)
Support: This research was funded by Johnson and Johnson Vision
Care, Inc.
Coefficient of Friction Analysis of Unworn and Worn Daily
Disposable Contact Lenses
Jeffery Schafer, Daniel Hook, Charles Lusignan, Robert B. Steffen.
Bausch & Lomb, Rochester, NY.
Purpose: To evaluate the effect of lens wear on coefficient of friction
(CoF) as compared to unworn daily disposable contact lenses.
Methods: Five subjects bilaterally wore nesofilcon A, delefilcon
A, nelfilcon A, narafilcon A, etafilcon A, and omafilcon A daily
disposable contact lenses in a random order for 4 hours each. CoF
measurements were obtained via TA Instruments DHR3 stress
rheometer. Lenses were immersed in BBS, conformed around a 6 mm
diameter polished stainless steel ring-shaped rub tool, and allowed to
relax until the axial force stabilized at a contact pressure of ~ 2 kPa,
similar to eyelid pressure.
Results: For unworn lenses, the mean (SD) static CoF was 0.04
(0.02) for nesofilcon A, 0.63 (0.12) for delefilcon A, 1.44 (0.40) for
nelfilcon A, 0.03 (0.00) for narafilcon A, 0.06 (0.01) for etafilcon
A, and 0.16 (0.06) for omafilcon A. For worn lenses, the mean (SD)
static CoF was 0.14 (0.07) for nesofilcon A, 0.91 (0.21) for delefilcon
A, 1.56 (0.67) for nelfilcon A, 0.12 (0.08) for narafilcon A, 0.31
(0.09) for etafilcon A, and 0.64 (0.11) for omafilcon A. For unworn
lenses, the mean (SD) kinetic CoF was 0.05 (0.02) for nesofilcon A,
0.12 (0.02) for delefilcon A, 0.58 (0.14) for nelfilcon A, 0.05 (0.00)
for narafilcon A, 0.07 (0.01) for etafilcon A, and 0.06 (0.01) for
omafilcon A. For worn lenses, the mean (SD) kinetic CoF was 0.06
(0.02) for nesofilcon A, 0.13 (0.02) for delefilcon A, 0.47 (0.12) for
nelfilcon A, 0.07 (0.02) for narafilcon A, 0.40 (0.19) for etafilcon A,
and 0.10 (0.02) for omafilcon A.
Conclusions: Both static and low speed kinetic friction showed
variability among different daily disposable lens materials for
both worn and unworn lenses. nesofilcon A and narafilcon A had
the lowest static and kinetic CoF measurements for both worn and
unworn lenses, while nelfilcon A had the highest static and kinetic
CoF values for both worn and unworn lenses.
Commercial Relationships: Jeffery Schafer, Bausch & Lomb (E);
Daniel Hook, Bausch & Lomb (E); Charles Lusignan, Bausch &
Lomb (E); Robert B. Steffen, Bausch & Lomb (E)
Sliding Friction Coefficient of Soft Surface-Gel Coatings for Soft
Contact Lenses
Clayton J. Radke, Daniel Bregante, Halbert Chong, Thomas Dursch.
Chemical Engineering, Univ of California, Berkeley, Berkeley, CA.
Purpose: Minimal sliding friction of soft contact lenses (SCLs) is
now considered critical to wear comfort. Recently, SCLs (DAILIES
TOTAL1, DT1) have been introduced to reduce sliding friction by
coating a silicone-hydrogel core with a 10-mm thick hydrophilic
surface gel of high water content (ARVO 2014 E-6071). At this
thickness, the surface gels exhibit bulk gel properties. To ascertain
whether softness (i.e., low modulus) of high-water-content surface
gels leads to low sliding friction, we synthesized high-watercontent bulk gels and determined their moduli and sliding-friction
coefficients.
Methods: Bulk gels were synthesized by thermally reacting
hydrophilic azetidinium-functionalized polymer (polyamidoamine
epichlorohydrin, PAE) with random hydrophilic copolymer
(poly(acrylamide-co-acrylic acid), 500 kDa, 80/20, pAAm/AA) in
aqueous solution at 85 0C for 2 h. Solutions consisted of varying
PAE:pAAM/AA mass ratios and 80 wt% phosphate buffer saline
(PBS). Following equilibration in PBS for 2 d, equilibrium water
contents (w), zero-frequency storage and loss moduli (and ), and
critical coefficients of sliding friction (CCOF) were obtained from
gravimetric analysis, oscillatory shear rheology, and the inclinedplane method of Peng et al. (ARVO 2014 E-4062), respectively.
Results: Table 1 reports water contents, storage/loss moduli,
and CCOFs for the synthesized gels. The last two rows report
corresponding values for DT1 surface coatings and a pHEMA gel.
All PAE:pAAM/AA gels have high water content greater than 90%.
Storage moduli are larger than loss moduli. PAE:pAAM/AA gels are
“soft” with storage moduli 100 times smaller than pHEMA. Storage
moduli decrease with increasing water content, although small
changes in water content lead to large changes in storage moduli. For
all gels studied, CCOF is low and basically unchanged.
Conclusions: For high-water-content gels, large changes in storage
modulus occur with minor changes in water content. Hence, gel
chemistry/structure is more important in determining gel softness
than is water content. CCOF, although low, is insensitive to water
content. Two possible explanations are: (1) at low CCOF values, the
sensitivity limit of the inclined-plane method is reached; (2) CCOF
is determined by gel surface properties not reflected in the storage
moduli, such as dangling polymer ends (ARVO E-Abstract 500).
Commercial Relationships: Clayton J. Radke, None; Daniel
Bregante, None; Halbert Chong, None; Thomas Dursch, None
A device to model pollen deposition on contact lenses
Kevin van Doorn1, Lakshman Subbaraman1, Jessie Lemp2, Cecile
A. Maissa2, Lyndon W. Jones1. 1Centre for Contact Lens Research,
School of Optometry & Vision Science, University of Waterloo,
Waterloo, ON, Canada; 2Alcon Laboratories Inc., Fort Worth, TX.
Purpose: Windborne pollen is implicated in seasonal allergies,
including ocular symptoms, and pollen adhesion to contact lens
(CL) materials may increase direct exposure time and the likelihood
that grains will break down and release their allergenic cytoplasmic
contents. The purpose of this project was to develop a device for
exposing CL materials to windborne pollen and allow quantification
of pollen deposition.
Methods: A small, modular bench top wind tunnel was fashioned
and validated. It consists of an enclosed circular tunnel within
which CLs can be mounted and through which pollen is carried by
adjustable air velocities generated by 2 equidistant fans within the
tunnel. Validation of the chamber’s capability to deterministically
deposit pollen on lenses was undertaken using 4 pollen species
(white pine, common ragweed, Kentucky bluegrass, silver birch)
and 7 commercial hydrogel and silicone hydrogel lens types. CLs
were tested with and without prior incubation in an artificial tear
solution (ATS). Exposures were run for 30 seconds at 5 mph and
concentrations from 106-107 grains/m3, depending on pollen type,
which simulates an accelerated 13 hour exposure of 640-1200 grains/
m3, a range often encountered during allergy season. Exposed CLs
were imaged under brightfield or fluorescence microscopy for pollen
counting. Analyses were conducted on all lens types pooled together
to obtain a global impression of pollen deposition.
Results: The chamber successfully deposited pollen on CLs and
significant differences were found between pollen species in their
deposition (p<0.0001). No statistical difference was noted due to
ATS incubation (p=0.0924), although there was a trend of reduced
deposition (Fig 1).
Conclusions: The device has proven successful at depositing pollen
on CL materials. It may be used to measure the adherence of different
species of pollen at varying concentrations and exposure times to any
CL material.
which coma and residual astigmatism are significant, designs with
a higher number of areas will provide a more predictable optical
performance across subjects. Although designs with angular divisions
provide a better optical performance, their interactions with residual
astigmatism and natural coma is stronger than the one occurring with
radial divisions. SA does not show any strong interaction with radial
or angular designs.
Mean number of deposited pollen grains of all species (concentration
normalized) on lenses with and without incubation in ATS
Commercial Relationships: Kevin van Doorn, Alcon Laboratories
Inc. (F); Lakshman Subbaraman, Alcon Laboratories Inc. (F);
Jessie Lemp, Alcon Laboratories Inc. (E); Cecile A. Maissa, Alcon
Laboratories Inc. (E); Lyndon W. Jones, Alcon Laboratories Inc. (F)
Stability of multifocal lenses in subjects with residual
astigmatism, coma, and spherical aberration
Pablo De Gracia. Neurobiology, Barrow Neurological Institue,
Phoenix, AZ.
Purpose: To evaluate the effects of normal residual values of
astigmatism after proper prescription and normal values of coma over
the optical performance of multifocal lenses. This study compares the
performance and the stability against the effects of coma, spherical
aberration (SA), and astigmatism of various design philosophies.
Methods: A computer model was developed to test the interaction
of bifocal (2 and 4 zones) and trifocal designs (3 and 6 zones) with
astigmatic values ranging from 0 to 1 D, of coma ranging from 0 to 1
mm, and of spherical aberration ranging from 0 to 1 mm. The optical
performance was evaluated by calculating the through focus values
of an optical quality metric (VSOTF) for angular (slices of a pizza)
and radial (concentric circles) designs. The area under the curve;
the change introduced by coma, SA, and astigmatism in the original
VSOTF of the different designs; and the range above threshold are
used as the indexes to evaluate the optical performance of such
interactions. Computations are repeated for pupil diameters of 3, 4, 5,
and 6 mm.
Results: Designs with a higher number of zones (4 and 6 zones) are
more stable against the effects of astigmatism and coma. Normal
residual values of astigmatism of 0.5 D distort on average a 10% the
initial profile. A strong interaction between the direction of coma and
bifocal 2 angular designs has been found. Optical performance of
angular designs is superior to that provided by radial designs. Radial
designs are, because of their marked differences in geometry with the
two aberrations studied, more stable against coma and astigmatism
than angular designs.
Conclusions: When prescribing multifocal prescriptions, astigmatism
should be corrected to the lowest value possible. In the cases in
Commercial Relationships: Pablo De Gracia, None
Support: Bisgrove Scholar. Science Foundation of Arizona
Ocular Signs and Symptoms in non-symptomatic CL wearers
under controlled humidity settings in an Environmental
Exposure Chamber (EEC)
Fiona Soong2, Holly I. Lorentz2, Stephanie Recker2, Chuck Shi1,
James J. Mun1, Anne Marie Salapatek2. 1Coopervision Inc.,
Pleasanton, CA; 2Inflamax Research Inc., Mississauga, ON, Canada.
Purpose: An investigational study to evaluate ocular signs and
symptoms of non-symptomatic CL wearers in low and moderate
humidity conditions using the Environmental Exposure Chamber
(EEC) model.
Methods: 10 non-symptomatic adapted CL wearers were screened
and randomized to a treatment sequence of two different CL materials
(etafilcon A [ETA] and senofilcon A [SEN]) worn at four EEC visits
in which the environmental conditions were set to either 10±3% RH
or 50±5% RH, an air flow of 2-5ft/sec and a temperature of 23±3°C.
On each EEC visit, objective measures such as TBUT, corneal and
conjunctival staining, conjunctival redness, blink rate and LWE were
taken prior to EEC entry and CL insertion as well as post EEC exit
and CL removal. Subjective symptoms including grittiness, tearing,
burning, itching, dryness, soreness, sensitivity to light, blurring, and
discharge were rated 0-4 using electronic Patient Data Acquisition
Tablets (ePDAT™) at set intervals during the visit.
Results: All objective and subjective measures deteriorated with
exposure time in both controlled humidity EEC settings when lenses
were worn on eye for 150min. Conjunctival redness LSMeans,
was statistically higher (p<0.05) in the RH 10% condition (max
3.44±1.49) than the RH50% condition (max 2.35±1.25). Blink rate
per minute increased for the first 40 minutes before reaching a plateau
and the LSMeans was statistically higher (p<0.05) in RH10% (max
43.85±17.95) than RH50% conditions (max 35.20±12.17).
Conclusions: The EEC model can control humidity, air flow and
temperature to elicit dry eye conditions in a short period of time
in CL wearers who are habitually non-symptomatic. In this small
investigational study that determined differences in CL dehydration,
conjunctival redness and blink rate were the two measurements that
showed differentiation between the two RH conditions.
Commercial Relationships: Fiona Soong, Inflamax Research
Inc. (C); Holly I. Lorentz, Inflamax Research Inc. (E); Stephanie
Recker, Inflamax Research Inc. (E); Chuck Shi, None; James J.
Mun, None; Anne Marie Salapatek, Inflamax Research Inc. (E)
A novel method for monitoring corneal surface temperature
fluctuation in three dimensions
Yunwei Feng, Paul Murphy. School of Optometry and Vision Science,
University of Waterloo, Waterloo, ON, Canada.
Purpose: To develop a method of quantitatively assessing ocular
surface temperature fluctuation (OSTF) in three dimension (time,
temperature change and area (percentage)) using dynamic thermal
imaging
Methods: A FLIR infrared thermal camera (FLIR SC605, FLIR
Systems), with a temperature sensitivity of <0.05°C at 30°C,
frame recording frequency of 50Hz and image resolution of 640 x
480 pixels, was used to record human ocular surface temperature
(OST) for 9 seconds after a blink in the right eye. The whole cornea
surface was selected as the area of interest (AOI) using the FLIR
software. Initial OST after a blink was assigned as the baseline. The
fluctuation of OST was defined as the change in OST from baseline,
and a calculation was done by subtracting the raw temperature data
(extracted from the FLIR software output) at baseline from that of
each assigned time point after the blink, using custom-designed
software. The percentage of the temperature fluctuation in 0.2°C steps
at each time point of the AOI was analyzed, colour coded and then
animated.
Results: The corneal surface temperature gradually decreased during
the 9-second period, with a greatest initial reduction slope over the
first second. A decreased temperature was observed, starting at the
middle-inferior cornea and spreading peripherally, especially to
the temporal cornea, through the 9-second recording period, in this
particular participant. The dynamic temperature change pattern was
consistent. Subsequent analysis of this output revealed percentage
ocular surface area change for a range of temperature fluctuations,
which will help to address image analysis challenges from the
infrared camera output.
Conclusions: Ocular surface temperature fluctuation could be
dynamically monitored in a selected area using FLIR infrared thermal
camera and custom software. This technique will facilitate further
study of the contribution of OST to tear break-up and ocular surface
sensation.
Commercial Relationships: Yunwei Feng, None; Paul Murphy,
None
and polyacrylamide (PAAm) in a Gemini interface2 were explored to
elucidate the origins of this transition in lubricity.
Methods: To create a Gemini contact, a probe and a disk were
made of 7.5% polymer3. The probe had a radius of curvature of 2
mm and the hydrogel disk was 4.5 mm thick and 30 mm in radius.
The contact area was determined by in situ microscopy during an
indent. Indentations were performed by loading the probe against
the disk to 2 mN at a rate of 65 mm s-1 with a microtribometer.
Prior to indents, the system was heated above the lower critical
solvation temperature (LCST) of pNIPAM. Indents were performed
continuously throughout the cooling process until the system reached
room temperature.
Results: For high-water content hydrogels in a swollen state we see
low stiffness and adhesion and the loading and unloading curves
show nearly Hertzian behavior. Hydrogels in a collapsed state exhibit
nearly twice the stiffness and an order of magnitude increase in
adhesion force and indentation curves followed the Johnson-KendallRoberts (JKR) model of elastic contact.
Conclusions: Previous work was performed with glass probes,
but a Gemini hydrogel configuration better models the ocular
environment. A gel with zero adhesion obeys traditional Hertzian
contact mechanics. If adhesion were to occur between a contact lens
and a biological surface in the eye, our results suggest that the contact
mechanics of this system would be better described by JKR Theory.
Acknowledgements: This work was funded by Alcon Laboratories
References: 1. Dunn AC, Urueña JM, Huo Y, Perry SS, Angelini
TE, Sawyer WG. Lubricity of Surface Hydrogel Layers. Tribol Lett
2013; 49:371-378. 2. Dunn AC, Sawyer WG, Angelini TE. Gemini
Interfaces in Aqueous Lubrication with Hydrogels. Tribol Lett 2014;
54:59-66. 3. Pitenis AA, Urueña, Schulze KD, Nixon RM, Dunn AC,
Krick BA, Sawyer WG, Angelini TE. Polymer fluctuation lubrication
in hydrogel Gemini interfaces. Soft Matter 2014; 10, 8955
Commercial Relationships: Angela A. Pitenis, Alcon Laboratories
(F); Juan M. Uruena, Alcon Laboratories (F); Kyle Schulze, Alcon
Laboratories (F); Ryan Nixon, Alcon Laboratories (F); Alison C.
Dunn, None; Wallace G. Sawyer, A (F); Thomas Angelini, Alcon
Laboratories (F)
Support: Alcon Laboratories
Contact Mechanics of High Water Content Hydrogels
Angela A. Pitenis1, Juan M. Uruena1, Kyle Schulze1, Ryan Nixon1,
Alison C. Dunn2, Wallace G. Sawyer1, 3, Thomas Angelini1, 4.
1
Mechanical and Aerospace Engineering, University of Florida,
Gainesville, FL; 2Mechanical Science and Engineering, University
of Illinois at Urbana-Champaign, Urbana, IL; 3Materials Science
and Engineering, University of Florida, Gainesville, FL; 4J. Crayton
Pruitt Family Department of Biomedical Engineering, University of
Florida, Gainesville, FL.
Purpose: The relationship between contact lens comfort and the
stiffness of the lens surface is not well understood. Recently, sliding
glass probes against contact lenses with hydrogel surface gels has
shown low friction at low loads and high friction at high loads,
indicating gel collapse1. In this work, the contact mechanics of high
water content hydrogels poly(N-isopropylacrylamide) (pNIPAM)

ARVO 2015 Annual Meeting Abstracts 541 Contact lens Thursday

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