1. OCT in Amblyopia
Lionel Kowal

2. 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

3. 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.

4. 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.

5. 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

6. OCT in Amblyopia Methods
OCT to measure macular thickness
Scan accepted if the following apply:
Centration reflection is central
Centre of scan is blue
Signal strength of 4 or above
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

7. OCT in Amblyopia
Results Analysis by Dr E Wong

8. Korean J Ophthalmol. 2006; 20(3):177-81. Kee SY, …
Thicknesses of the fovea and retinal nerve fiber layer in amblyopic and normal eyes in children
Korean J Ophthalmol. 2006; 20(3): 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.

9. 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 in normal eyes and was 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

10. 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 and 173.1, respectively, and the retinal nerve fiber layer thicknesses were measured to be and 92.8, respectively, and these were statistically significant differences (p = 0.046, 0.034, respectively).

11. OCT on 14 pts with unilateral strabismic amblyopia; aged 5-18 y
Thickness of the retinal nerve fiber layer, macular thickness, and macular volume in patients with strabismic amblyopia
J Pediatr Ophthalmol Strabismus Jul-Aug; 42(4): 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.

12. RESULTS: The mean age (+/- SD) was 10.4y (+/- 4y).
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

13. 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

14. 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 ….