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 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

OCT in Amblyopia Results Analysis by Dr E Wong

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):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).

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. 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.

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

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 ….