THE REPEATABILITY AND VARIABILITY OF THE MULTIFOCAL ELECTRORETINOGRAMFOR 4 DIFFERENT ELECTRODES

Multifocal electroretinograms were recorded from twelve subjects on th ree separate days using the Visual Evoked Response Imaging System (VER IS), The subjects were 18-40 years-of-age. Each recording session was separated by an interval of between one and 16 weeks. Four electrode t ypes were compared: the JET contact lens electrode, the gold foil elec trode, the DTL thread electrode and the carbon fibre (c-glide) electro de, The b-wave amplitude density (nV/ sq.deg) recorded with each elect rode was measured, The mean amplitude density recorded at each session for each subject and each electrode was calculated and compared. Ther e were no significant differences in amplitude density for the ERGs re corded with each type of electrode over the three days. The coefficien t of variation for each electrode and each subject was then calculated using the results for the three days. The coefficients of variation f or each electrode showed significant differences (One-way ANOVA: F= 4. 51, d.f. = 3, 44, P < 0.008). The c-glide electrode results had the hi ghest variability and post hoc tests showed that its coefficient of va riation was significantly different from those of the JET and gold foi l electrodes but not from that of the DTL thread electrode. Copyright (C) 1997 The College of Optometrists. Published by Elsevier Science Lt d.