Visual evoked potential in young adults: a normative study.

It is important to acquire adequate normative data of visual evoked potential before using it as a diagnostic tool. A study using visual evoked potential with pattern (VEP-P) was conducted in Twenty male and seven female young healthy subjects of 17-35 years age. Ag/Agcl electrodes anchored on scalp with collodion at O1-A1, O2-A2 (10-20 system), with transition skin to electrode impedence kept at less than 5 K ohms were connected to MEB 5200 Evoked potential Recorder (Nihon Kohden, Japan). The evoked responses to 256 visual stimuli were recorded using transient pattern reversal (checker size 32'), frequency 1/sec and contrast between black and white checks 67%. The responses were averaged by the computer and absolute peak latency values for P100 alongwith other positive and negative waves worked out. P100 latency of 95.37 +/- 6.85, amp. 6.4 +/- 2.38 for males and 91.07 +/- 49 msec, amp. 6.88 +/- 2.79 microv for females are being reported. The P100 latency values of present study are similar to those reported in age and sex matched subjects of the western world, indicating that there are no ethnic variations in P100 of VEP.