Pattern-reversal electroretinographic acuity in untreated eyes with subfoveal neovascular membranes

To define further the natural history of visual loss in eyes with age-related macular degeneration (ARMD) complicated by a subfoveal neovascular membrane, pattern-reversal electroretinograms (ERGs) were obtained from patients randomized to no treatment at the Dallas center of the Macular Photocoagulation Study (Texas Retina Associates). Study eyes (n = 20) were tested during the initial visit and at 3-, 6-, and 12-month follow-up visits. Responses were obtained to phase-alternating checkerboards of varying check size. Extrapolation of the best-fit regression line relating the logarithm of the check size to amplitude was used to determine "retinal" acuity (log MAR). The pattern-reversal ERG acuity rating (100 - [50 x log MAR]) was derived for each visit. Pattern-reversal ERG acuity ratings for all patients across visits were correlated significantly with visual acuity ratings derived from the Bailey-Lovie chart (r = 0.61, P less than 0.001) and inversely related to neovascular membrane area (r = -0.55, P less than 0.001). During 1 yr of follow-up, pattern-reversal acuity ratings dropped from 53 to 12, corresponding to an average decrease of approximately 0.2 octaves/month. These results suggest that the pattern-reversal ERG, which samples the resolving power of the central 20 degrees, is a sensitive index of visual loss in age-related macular degeneration.