Abstract
Abstract: :
Purpose: To compare the responses generated using black/white multifocal visual evoked potential (m-VEP) with isoluminant blue/yellow m-VEP. Methods: 10 normal subjects were recruited from the community. A 25Hz cortically scaled pattern reversal stimulus consisting of 3 rings (eccentricity 1ºto3º, 3ºto12º, 12ºto26º, identical to the m-VEP stimulus) with fixed maximum blue luminance and variable yellow luminance was presented on a computer monitor. For each ring the subject determined the luminance at which there was a minimally distinct border between the blue and yellow checks. The isoluminant point thus obtained was measured 6 times for each ring. Using the averaged isoluminant valuess for the 3 rings, blue/yellow m-VEP was recorded. The amplitude and latency of signals were compared with those obtained with a black/white m-VEP. Results: In all individuals there was a gradual increase from the centre to periphery in the amount of yellow luminance needed to achieve isoluminance. There was no significant difference in the amplitude obtained using blue/yellow and black/white m-VEP for the full field (p=0.49) and at different eccentricities (p>0.1). There was a significant delay in the blue/yellow latency of 19 ± 3 ms (p<0.001) when compared with black/white m-VEP. Similar delay was present in all 3 rings in the superior and inferior fields. Conclusion: Isoluminant blue/yellow pattern reversal m-VEP generates signals of similar amplitude to black/white m-VEP. This may be useful in the early diagnosis of glaucoma.
Keywords: electrophysiology: clinical • visual fields