SPATIAL CONE ACTIVITY DISTRIBUTION IN DISEASES OF THE POSTERIOR POLE DETERMINED BY MULTIFOCAL ELECTRORETINOGRAPHY

Thirty patients with a reduced central vision due to diseases of the p osterior pole were examined with the VERIS system developed by Sutter and Tran (Vis Res 1992;32:433-446) to characterize the topography of e lectroretinographic (ERG) changes in comparison to the results in 30 n ormal volunteers. Diagnoses included Stargardt's macular dystrophy (SM D, n=10), age-related macular degeneration (AMD, n = 5), cone dystroph y (CD, n = 5), central retinal vein occlusion (CRVO, n = 5), and autos omal dominant optic atrophy (ADOA, n=5). The 61 local responses obtain ed from each subject were grouped by eccentricity to form five concent ric rings. The foveal ERG, originating from a central area of 2 degree s radius, was non-recordable or markedly diminished in all patients ex cept those with optic atrophy; where amplitudes were found to be in th e normal range. In patients with advanced stages of SMD, functional de fects were larger and involved more peripheral areas than in patients with early stages of SMD or with AMD. A reduction of response amplitud e even in the most peripheral ring (17-30.5 degrees eccentricity) was found in cone dystrophies and-moderately-in patients with advanced SMD and central retinal vein occlusion only. Prolonged implicit times wer e found in all bur the patients in early stages of SMD and they were m aximal in patients with CRVO. This study shows that the multifocal ERG (MFERG) can contribute to differential diagnosis of retinal diseases of the posterior pole especially in cases with a normal photopic Ganzf eld ERG. (C) 1998 Elsevier Science Ltd. All rights reserved.