Dichoptic multifocal visual evoked potentials identify local retinal dysfunction in age-related macular degeneration

Abstract

To evaluate the ability of multifocal visual evoked potentials (mfVEPs) to identify functional loss in patients with early and exudative age-related macular degeneration (AMD). A dichoptic multifocal stimulus presentation was employed to investigate the regional effects of AMD and the potential diagnostic utility in macular disease. MfVEP responses were recorded from 19 unilateral exudative AMD patients with non-exudative (n = 15) or normal (n = 4) presentations in the fellow eye and 28 age-matched controls. Root mean square (RMS) waveforms were pooled across selected EEG channels to produce global field RMS (gfRMS) waveforms. GfRMS amplitudes and response delays were analysed by multivariate linear models, and diagnostic capacity was measured using areas under the curve (AUC) of receiver operator characteristic plots. The mean gfRMS amplitude of the exudative eye of AMD patients was significantly reduced compared with the controls (-2.03 ± 0.08 dB, t = -12.9). Fellow non-exudative AMD eyes were less effected but still significantly reduced (-0.84 ± 0.07 dB, t = -11.5). No significant difference in mean gfRMS delay of AMD eyes across the central 46° was observed. AUC values of 100 ± 0.0% (mean ± SE) for exudative and 79.7 ± 6.5% for non-exudative eyes were obtained for response amplitudes. The study demonstrated that mfVEP identified retinal dysfunction in both exudative AMD and fellow non-exudative AMD eyes, but mostly affecting the macular field. The reduced testing duration and good diagnostic accuracy suggest that dichoptic mfVEPs may be a sensitive tool for monitoring progression in AMD.