INVESTIGATION OF MULTIFOCAL VISUAL-EVOKED POTENTIAL IN ANISOMETROPIC AND ESOTROPIC AMBLYOPES

PURPOSE. TO investigate the variation of visual evoked potential (VEP) function at different eccentricities of the visual field in esotropic amblyopes and anisometropic amblyopes. METHODS. Data from 5 esotropic amblyopic eyes, 6 anisometropic amblyopic eyes, and 45 control eyes w ere analyzed. A VERIS system was used to generate a stimulus matrix co ntaining 61 hexagons on a computer monitor. Each hexagon of the displa y contained a number of small black and white hexagonal patches that r eversed in polarity during stimulation according to a pseudorandom bin ary m-sequence. The VERIS system extracted the local responses by cros s-correlating the input and output signals. The latencies and amplitud es of the responses from the central 8.6 degrees of are in the visual field were analyzed. RESULTS. In esotropic amblyopia, the multifocal V EP latency is prolonged, and the amplitude is reduced in the central r egion of the visual field. The mean amplitude is significantly smaller , and the mean latency is significantly longer in the temporal visual field than in the nasal visual field, In anisometropic amblyopia, late ncies are markedly prolonged, and the amplitudes of multifocal VEP are attenuated in the central region of the visual field, and these effec ts are lessened in the periphery. CONCLUSIONS. The results are in agre ement with psychophysical studies reporting a greater foveal deficit i n amblyopia and a greater visual loss in the temporal field than in th e nasal field in esotropic amblyopia.