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Acuity predictions from visually evoked potential to checkerboard pattern reversal stimuli: the effect of reversal
Shandiz J Heravian1, W A Douthwaite, T CA Jenkins
1Department of Optometry, Pirapezeshki Faculty, Mashhad University of Medical Sciences, Ahmadabad St, Parastar Avenue, Mashhad, Iran.
Abstract:
INTRODUCTION: A pattern reversal stimulus (check size 5.5 minutes of arc) was used to elicit the visually evoked potential (VEP). METHODS: The peak to trough amplitude of the VEP wave was measured and compared to subjective visual acuity (Landolt C). The recordings were made at three, six and 12 pattern reversals per second. RESULTS: The correlation between VEP amplitude and visual acuity was found to decrease at higher temporal frequencies. The decrease is not confined to the use of a television system reversing checkerboard pattern stimulus as suggested by previous workers. DISCUSSION: It may well be concerned with a change in processing of the visual information as could be expected at these higher frequencies.