The Rod–Mediated Multifocal Electroretinogram in Aging and in Early ARM Eyes

Abstract

Abstract: : Purpose:To investigate rod–mediated function with the multifocal electroretinogram (mfERG) in normal subjects and in subjects with early age–related maculopathy (ARM). Methods and subjects: Thirty subjects were tested with the rod–mediated mfERG; 10 healthy young subjects (mean age 31 years) and 10 healthy older subjects (mean age 71 years) formed groups 1 and 2 respectively and 10 early ARM subjects formed group 3 (mean age 71 years). To approximate the influence of cataract, five subjects of group 1 were re–tested with added neutral density filters (0.3 ND) (group 4). The first–order N1P1 amplitude and P1 latency responses were analysed. The unscaled 61 hexagons were averaged into 4 rings to examine topographical differences. Funduscopic and lens changes as defined by Age–Related Eye Disease Study Research Group criteria (AREDS) were correlated with the mfERG parameters. Results:P1 latencies were significantly delayed in groups 2 (p=0.02) and 3 (p<0.001) compared to group 1. Group 3 showed significantly delayed results compared to groups 2 and 4 (p<0.01). In contrast there were no significant differences in N1P1 amplitudes between groups but there was a significant location effect for all groups with highest mean amplitudes for ring 4 (p<0.01). Significantly longer P1 latencies (p<0.05) were related to more advanced fundus changes. Conclusions:The rod–mediated mfERG is affected by aging and early ARM and is correlated with funduscopic changes. Although a preretinal cause cannot be excluded the findings suggest neuronal transmission alterations at the post–receptoral level in aging and in early ARM.

Keywords: age-related macular degeneration • aging: visual performance • electroretinography: clinical