The Development of Flash Visual Evoked Potential Techniques for the Diagnosis of Visual Disorders with Dense Opacities of the Optic Media

Abstract

Visual evoked potentials (VEP)were recorded in a large normal population. Significant age differences were found, and the P2 component (latency 116 m.sec.) was the most consistent component of the VEP both between and within the individuals. The validity of the normal VEP criteria were tested in two groups of patients with known visual field defects. One group with central lesions and hemianopia, and a second with senile macula degeneration. The VEP varied with the degree of visual impairment with low amplitudes, long latencies and no localization at either occiput being consistent with poor acuity. The P2 component appeared to be particularly effected by the loss of central retinal function. Two prospective studies were carried out on patients with dense opacities of the optic media. One group of patients had unilateral longstanding cataracts, the second group had recently sustained severe eye injuries with penetration of the globe. The VEP was graded to predict a good visual recovery or no useful function remaining and the gradings were significantly correlated with the final visual outcome. It was concluded that the flash VEP is particularly useful to monitor visual function with dense opacities of the optic media if there is damage to the central retina or visual pathways and cortex.