Normative values of visual evoked potentials in Northeastern of Iran.

PURPOSE: Visual evoked potentials (VEPs) provide important diagnostic information related to the functional integrity of the visual pathways. The aim of this study was to establish normative values of different components of pattern reversal VEPs on Iranian normal adult subjects. METHODS: Monocular and binocular pattern reversal VEPs were recorded on 59 healthy participants (22.55±3.79 years old) using the Roland RETI system for two check sizes of 15 and 60min of arc. The measured VEP components were the latencies of N75, P100, N135 and amplitude of N75-P100. RESULTS: Repeated measures ANOVA showed that viewing eye condition has a significant impact on the amplitude of N75-P100 (P<0.001, F=13.89). Also, the effect of check size on the latencies of N75, P100, N135, amplitude of N75-P100 (P≤0.010), as well as the intraocular difference of P100 latency and amplitude N75-P100 (P=0.007) was significant. More specifically, the amplitude of N75-P100 in both check sizes significantly differed between gender groups (P<0.023). CONCLUSION: According to the results of this study, VEPs components are affected by the stimulus size, monocular and binocular recording conditions and gender. Therefore, it is necessary to determine the normative values of VEPs in each population, so that the results could be used in clinical studies.