- Oertli Instrumente AG

Long-term results of a novel minimally invasive,
high frequency deep sclerotomy (HFDS) ab interno
surgical procedure for glaucoma
Brigitte Pajic-Eggspuehler, MD, Bojan Pajic, MD, PhD, FEBO, Ivan Haefliger, MD, PhD, FEBO
Swiss Eye Research Foundation, Eye Clinic ORASIS, Titlisstrasse 44, 5734 Reinach, Switzerland
Division of Ophthalmology , University Hospitals of Geneva, Switzerland
Eye Hospital VIDAR-ORASIS Swiss, University of Novi Sad , Faculty of Physics
Purpose
The aim of this study is to demonstrate the efficacy and safety of a new surgical procedure termed high frequency deep
sclerotomy ab interno (HFDS, former STT) for the treatment of primary open-angle glaucoma and juvenile glaucoma.
Patients and Methods
The main inclusion criterion for this study was an insufficient response to medical treatment of IOP. Data was
documented according to a prospective study protocol. Fifty-three HFDS procedures ab interno in 53 patients with
primary open-angle glaucoma and 5 with juvenile glaucoma were carried out between 1 April 2002 and 31 July 2002.
®
High-Frequency Diathermic Probe (abee Glaucoma Tip, Oertli Instrumente AG)
The high-frequency diathermic probe consists of an inner platinum electrode which is isolated from the outer coaxial
electrode. The platinum probe tip is 1 mm in length, 0.3 mm high and 0.6 mm width and is bent posteriorly at an angle of
15° (Figure 1a,b). The external diameter of the probe measures 0.9 mm. Modulated 500 kHz current generates a
temperature of approximate 130°C at the tip of the probe. The setup provides high frequency power dissipation in close
vicinity of the tip. As a result, heating of tissue is locally very limited and is applied as a rotationned ellipsoid.
Surgical Procedure
A clear cornea incision (1.2 mm wide) was placed in the temporal upper quadrant using a diamond knife. A second
corneal incision was performed 120° apart from the first followed by injection of Healon GV. The high-frequency
®
diathermic probe (abee Glaucoma Tip, Oertli Instrumente AG) was inserted through the temporal corneal insertion.
Visual inspection of the target zone (opposite iridocorneal angle) was observed by a 4-mirror gonioscopic lens. The high
frequency tip penetrates up to 1mm nasal into the sclera through the trabecular meshwork and Schlemm canal (figure
2,3), forming a deep sclerotomy (i.e. “thalami”) of 0.3 mm high and 0.6 mm width (figure 4). This procedure was repeated
4 times within one quadrant. Healon GV was evacuated from the anterior chamber with bimanual irrigation/aspiration.
Figure 1a,b: abee® Glaucoma Tip (Oertli Ref. VE201751)
Figure 2: Penetration of
the high frequency tip
Figure 3: Penetration up to
1mm nasal into the sclera
Figure 4: Thalamus: 0.3mm
high and 0.6mm width
Results
Mean age of patients with open-angle glaucoma was 72.3±12.3 years (range: 15-92 years. 17 patients (32%) were
female, 36 patients (68%) male and mean age of patients with juvenile glaucoma was 9±1.4 years (range: 7-11 years. 1
patients (20%) were female, 4 patients (80%) male. In 25 cases (47.4%) the right eye in 28 cases (52.6%) the left eye
with open-angle glaucoma and in 3 cases (60%) the right eye in 2 cases (40%) the left eye with open-angle glaucoma
were treated. Decimalised Snellen visual acuity (VA) was for open-angle glaucoma 0.7±0.3 (range 0.1 to 1.0) and for
juvenile glaucoma 0.58±0.3 (range 0.1 to 0.8) preoperatively. For all patients the follow-up was 72 months.
Oertli Instrumente AG
CH-9442 Berneck
Switzerland
Phone +41 (0)71 747 42 00
Fax: +41 (0)71 747 42 90
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Mean preoperative IOP in the study population of 53 patients with primary open-angle glaucoma was 25.6 ± 2.3 mmHg
(range18 to 48 mmHg) and study population of 5 patients with juvenile glaucoma was 39.6 ± 2.3 mmHg (range 34 to 46
mmHg). Mean IOP after 72 months was 14.7 ± 1.8 mmHg (range 10 to 21 mmHg) for primary open-angle glaucoma and
13.2 ± 1.3 mmHg (range 12 to 15 mmHg) for. The IOP drop for both groups were statistically highly significant p<0.001)
at all measured postoperative intervals (figure 5, 6). Pressure reduction at any time of standardised follow up was
statistically significant compared to preoperative data at a level of α<0.03 (Bonferroni corrected). In the group of juvenile
glaucoma with 5 patients there are not enough cases to get a conclusive statistics but the results show the tendency.
At month 72 after surgery, 52.8% of patients with open-angel glaucoma had an IOP<15 mmHg, 76% had an IOP<18
mmHg and 79.2% had an IOP<21 mmHg (figure 7) and 80% of patients with juvenile glaucoma had an IOP<15 mmHg,
100% had an IOP<18 mmHg. After 72 months, 84.9% achieved >20% reduction in IOPs and 77% of treated patients with
open-angel glaucoma achieved >30% reductions of the IOP. After 72 months, 100% of treated patients with juvenile
glaucoma achieved >30% reductions of the IOP. The complete success rate, defined as an IOP lower than 21 mmHg
without medication, was 79.2% in the group of open-angel glaucoma and 80% in the group of juvenile glaucoma at 72
month. Qualified success rate, defined as an IOP lower than 21 mmHg with medication, was 100% for all patients at 72
month (figure 8). After 72 months, it was necessary to administer IOP reducing medication in 11 eyes or 20.8% in openangle glaucoma group (figure 9) and 1 eye or 20% in the juvenile glaucoma group of all cases.There is no significant
changes comparing the visual field at baseline with mean defect MD 8.38±2.44, loss variance LV 27.7±5.11 and at 72
months with MD 9.03±2.45, LV 28.2±5.66 (p=0.29 for MD, p=0.37 for LV) for open-angle glaucoma (figure 10) and at
baseline with mean defect MD 8.73±3.12, loss variance LV 28.2±29.45 and at 72 months with MD 9.9±1.97, LV
21.3±14.15 (p=0.56 for MD, p=0.72 for LV) for juvenile glaucoma (figure 11).
50
100
45
45
90
40
40
80
35
35
70
30
30
..
25
Patients (%)
25
20
60
20
15
15
10
10
5
1
30
2 3
4
40
5
30
20
10
0
31
30 29 28
27 26 25
24
6
0
8
<16
<19
<20
3
6
12
24
36
48
60
72
months months months months months months months months
time in months
25
27.66
22.72
26.7
20
Temporary IOP
elevation
Temporary
hypotension
Hyphema
20
11.4%
15
15
10.12
10
10
22.6%
8.83
8.38
1.9%
5.78
5.32
5
5
0
Temporary fibrin
formation
0
MD
LV
Octopus visual field G2 at baseline
Figure 8: POAG: Preoperative and
postoperative level of IOP 48
months of follow-up
<18
1.9%
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
<17
Figure 7: POAG: Percentage of patients Figure 9: Administration of pressurereaching specified intraocular pressure reducing eye agents during 72 months
(IOP) levels
for group with POAG
25
7
preop 1 month
<15
dB
53
30
2.8
2.7
2.6
2.5
2.4
2.3
2.2
2.1
2
1.9
1.8
1.7
1.6
1.5
1.4
1.3
1.2
1.1
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
Mean diurnal IOP (mmHg)
Figure 6: Juvenile glaucoma: Average
level of intraocular pressure (IOP)
dB
50
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
32
51 52
<22
40
time in months
mmHg
50
<21
67.2
60.4
52.8
50
4d
1 7d
m
3 onth
m
6 onth
m
9 onth
m
12 on
m th
15 on
m th
18 on
m th
21 on
m th
24 on
m th
27 on
m th
30 on
m th
33 on
m th
36 on
m th
39 on
m th
42 on
m th
45 on
m th
48 on
m th
51 on
m th
54 on
m th
57 on
m th
60 on
m th
63 on
m th
66 on
m th
69 on
m th
72 on
m th
on
th
op
1d
2d
3d
pre
p
1d
2d
3d
4d
1 7d
m
3 ont
m h
6 ont
m h
9 ont
m h
12 on
t
15 mon h
t
18 mon h
t
21 mon h
t
24 mon h
t
27 mon h
t
30 mon h
t
33 mon h
t
36 mon h
t
39 mon h
t
42 mon h
t
45 mon h
t
48 mon h
t
51 mon h
t
m
54 on h
t
m
57 on h
t
60 mon h
t
63 mon h
t
66 mon h
t
69 mon h
t
72 mon h
m th
on
th
pr
eo
time in months
49
100
10
0
Figure 5: POAG: Average level of
intraocular pressure (IOP)
98.1
20
5
0
94.0
86.8
76
pressure-reducing eye
50
mmHg
mmHg
For the 5 cases with juvenile glaucoma no side effects were seen up to now. With more cases complications could be
visualized as following described for the open-angle glaucoma group. Temporary IOP elevation higher than 21 mmHg
was observed in 12 of 53 eyes (22.6%). These patients responded well to pressure-reducing treatment with one agent
and medication could gradually be withdrawn in all of these patients. A single case of hypotension (1.9%) that lasted for
3 days after surgery was observed. Hyphema was present in 6 cases (11.4%) which disappeared within the first 2 weeks
after surgery. One eye (1.9%) exhibited transient fibrin formation. Fibrin was cleared within one day after frequent
application of topical Dexamethasone (figure 12).
MD
LV
Octopus visual field G2 after 48 months
Figure 10: POAG: Visual field analysis
MD
LV
Octopus visual field G2 at baseline
MD
LV
Octopus visual field G2 after 48 months
Figure 11: Juvenile glaucoma: visual
field analysis
Figure 12: Complications after high
frequency deep sclerotomy (HFDS)
ab interno surgical procedure
Conclusions
High frequency deep sclerotomy (HFDS, former STT) ab interno is a minimally invasive, safe and efficacious surgical
technique for lowering IOP in open-angle glaucoma and juvenile glaucoma. Also, the technique avoids stimulation of
episcleral and conjunctival tissues as in trabeculectomy and conventional non-penetrating surgery. In this study,
diathermy was used to create 4 thalami and this corresponds to a resorption surface area of 2.4 mm². The number of
thalami chosen was arbitrary and seems to provide a sufficient long-term decrease of IOP as a low rate of postoperative
complications. There is potential for a further IOP drop if 6 applications are made and we are currently investigating it.
The authors have no financial interest in the subject matter of this study.
Oertli Instrumente AG
CH-9442 Berneck
Switzerland
Phone +41 (0)71 747 42 00
Fax: +41 (0)71 747 42 90
www.oertli-instruments.com
info@oertli-instruments.com