Retinal and Choroidal Thickness in Myopic Anisometropia

Abstract

We compared the retinal thickness (RT) and choroidal thickness (ChT) between the fellow eyes of nonamblyopic myopic anisometropes. The eyes of 22 nonamblyopic myopic anisometropes (≥ 1 diopter [D] spherical equivalent refraction [SER] anisometropia) were examined using spectral domain optical coherence tomography (SD-OCT). Customized software was used to register, align, and average multiple foveal OCT B-scan images from each subject to enhance image quality. Two independent masked observers manually determined the RT and ChT from each SD-OCT image up to 2.5 mm nasal and temporal to the fovea. Axial length (AXL) was measured using optical low coherence biometry during relaxed accommodation. The mean SER anisometropia was 1.74 ± 0.95 D and the mean interocular AXL difference was 0.58 ± 0.41 mm. There was no significant difference in foveal RT between the fellow eyes (P > 0.05). Mean subfoveal ChT was significantly thinner in the more myopic eye (252 ± 46 μm) compared to the fellow, less myopic eye (286 ± 58 μm) (P < 0.001). There was a moderate correlation between the interocular difference in subfoveal ChT and the interocular difference in AXL (r = -0.50, P < 0.01). Asian anisometropes displayed more regionally symmetrical (nasal-temporal) interocular differences in ChT profile compared to Caucasians. RT was similar between the fellow eyes of myopic anisometropes; however, the subfoveal choroid was significantly thinner in the more myopic (longer) eye of this anisometropic cohort. The interocular asymmetry in ChT correlated with the interocular difference in AXL.