Transcript OCT in Amblyopia - Private Eye Clinic

OCT in Amblyopia
Lionel Kowal
OCT in Amblyopia
Hypothesis:



Amblyopia : [@ least partly] reversible poor vision 2° to
abnormal visual devp’t in a morphologically normal
eye
Majority reverse with appropriate treatment
Treatment failures may have a subtle
“anatomical anomaly” that can account for
the lack of success
OCT in Amblyopia
Aims
 Using Optical Coherence Tomography (OCT)
to assess the anatomy of amblyopic eyes and
compare the anatomical measurements in those
with visual improvement and those without
visual improvement after appropriate amblyopic
treatment.
OCT in Amblyopia
Hypothesis
 Patients with “presumed” amblyopia where
vision does not improve with appropriate
treatment have anatomical anomalies such as
foveal or optic nerve hypoplasia that is not
detected by standard examination.
OCT in Amblyopia
Methods

Children who can do the test ; >4 years old

BCVA 6/24 or worse in the amblyopic eye

No explanation detected by usual examination
OCT in Amblyopia
Methods

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OCT to measure macular thickness
 Scan accepted if the following apply:
1. Centration reflection is central
2. Centre of scan is blue
3. Signal strength of 4 or above
4. SD of macular thickness less than 10% OR clearly
difference between thicknesses clearly exceeds SD
Macular thickness of those with BCVA
improved after amblyopia treatment compared
with those who didn’t
OCT in Amblyopia
Results Analysis by Dr E Wong
VA
Right
Dx
Left
Final VA
Right
Left
6
6
15
18
12
12
12
6
6
36
OCT mac
Amb
other
206
150
157
167
200
176
153
150
146
169
193
162.2
Improvement with Rx
1
2
3
4
5
6
9
180
30
12
28
120
8
6
360
Refractive
L anisometropia
R anisometropia
R anisometropia
L ET
Avg
paired t-test 0.2427
No improvement with Rx
1
2
3
4
5
6
7
12
6
6
6
19
45
90
24
60
24
30
30
9
9
L XT
L anisometropia
L ET
L ET
L ET
R ET
R ET
12
6
8
9
12
45
120
24
60
45
30
24
9
7
226
292
193
276
242
207
232
Avg
136
177
152
169
238
160
191
238.2857 174.7143
paired t-test 0.0063
SD
CI
95% CI
35.45285 33.01371
15.94125 14.8445
218 ± 21 173 ± 13
Thicknesses of the fovea and retinal nerve fiber
layer in amblyopic and normal eyes in children
Korean J Ophthalmol. 2006; 20(3):177-81. Kee
SY, …
OCT on 26 children (52 eyes) with
unilateral amblyopia that was due to
anisometropia or strabismus & on
42 normal children (84 eyes), for a
total of 136 eyes.
Thicknesses of the fovea and retinal nerve fiber
layer in amblyopic and normal eyes in children
Average age normal children 8.5Y, amblyopia 8y
Retinal thickness measurements from fovea,
and NFL thickness measurements from
superior, inferior, nasal and temporal
quadrants in the peripapillary region.
The average thickness of the fovea was 157.4 in
normal eyes and was 158.8 in amblyopic eyes (p
= 0.551).
The thicknesses of the superior, inferior, nasal and
temporal quadrants of the retinal nerve fiber
layer between the normal cf amblyopia children
not statistically significant
Thicknesses of the fovea and retinal nerve fiber
layer in amblyopic and normal eyes in children
Children with anisometropic cf strabismic
amblyopia, the average thicknesses of the
fovea were 146.5 and 173.1, respectively,
and the retinal nerve fiber layer
thicknesses were measured to be 112.9
and 92.8, respectively, and these were
statistically significant differences (p =
0.046, 0.034, respectively).
Thickness of the retinal nerve fiber layer, macular thickness, and
macular volume in patients with strabismic amblyopia
J Pediatr Ophthalmol Strabismus. 2005 Jul-Aug;
42(4):216-21. Altintas O, …. Turkey.
OCT on 14 pts with unilateral strabismic
amblyopia; aged 5-18 y
The RNFL thickness average analysis
program was used to evaluate mean
superior, inferior, temporal, and nasal
thickness. The data for all clock quadrants
(12 values averaged) = the overall RNFL.
The retinal thickness and volume analysis
program was used to evaluate macular
scans.
Thickness of the retinal nerve fiber layer, macular thickness, and
macular volume in patients with strabismic amblyopia
RESULTS: The mean age (+/- SD) was
10.4y (+/- 4y).
Mean visual acuity of 0.3 (+/- 5.70).
OCT parameters including the RNFL
thickness in all quadrants, overall RNFL
thickness, macular thickness, and macular
volume showed no significant
differences between the two groups
WHY ARE THESE RESULTS SO DIFFERENT TO
MINE?
It’s the fish that John West rejects….: I’m
very careful to exclude technically
imperfect / suspect scans [THE
MAJORITY!]
Difficult technique
Eccentric fixation a difficult confounder
..wait for Cirrus
OCT in Amblyopia
Conclusions
 There may be structural macular changes in
some cases of amblyopia
 May be a prognostic indicator for amblyopia
treatment
 Further studies required ….