Interocular Differences in Visual Acuity and Refractive Status Between Unilateral Early and Late Age-Related Macular Degeneration: A Nationwide Population-Based Study

Background/Objectives: Age-related macular degeneration (AMD) may affect the two eyes asymmetrically, but visual impairment is commonly classified by visual acuity (VA) in the better-seeing eye. We compared interocular-presenting VA differences in unilateral early versus late AMD, assessed the association between late AMD and worse VA in the AMD-affected eye, and compared refractive status between the affected and fellow eyes.

Methods

We analyzed 1112 adults aged ≥40 years with unilateral AMD (1049 early and 63 late) from the 2017–2020 Korea National Health and Nutrition Examination Survey. Interocular VA difference was calculated as the logMAR VA of the AMD-affected eye minus that of the fellow eye. Survey-weighted modified Poisson regression estimated prevalence ratios (PRs), adjusting for age, sex, anisometropia, and the interocular difference in absolute spherical equivalent refraction. Exploratory analyses examined neovascular AMD and geographic atrophy separately, and sensitivity analyses assessed alternative model specifications.