Unusual visual evoked potentials in patients with age-related macular degeneration

Among a series of patients with age-related macular degeneration (ARMD), a few individuals could be identified showing larger amplitudes of pattern reversal visual evoked potentials (prVEP) after stimulation of a central 3 degrees field compared to stimulation of a 13 degrees field although in the majority of ARMD patients and in normals, VEP amplitudes increased with increasing field size. An analysis of prVEPs recorded after stimulation of different macular zones showed that the 3 degrees central area and the perifoveal zone contributed differently to the 13 degrees response or macular response. Perifoveal activity in this subgroup of ARMD patients seemed to mask the foveal contribution to the macular prVEP. The cortical magnification factor in ARMD may be higher than in normal controls. Small-field stimulation techniques are therefore also recommended in patients with central retinal pathology.