VEP in Normal Eyes by Using Different Check-sizes

ABSTRACT

VEP is a gross electrical signal generated by the occipital region of the cortex in response to visual stimuli and it is useful in refraction, optic nerve disease, color blindness, amblyopia, field defect, macular disease, etc. We used Horizon computer with UTAS-E and normal VEP at different checksize was measured on 30 subjects(60 eyes) with visual acuity better than 1.0. The pattern reversal frequency was 2 Hz., analysis time was 250 msec., artifact reject threshold was 75 micro V., low-pass filter cut-off was 30Hz., high-pass filter cut-off was 1Hz. The check sizes used were 16 X 16(50min), 32 X 32(25min) and 64 X 64(12.5min). The results were as follows; 1. 16 X 16 (50min). amplitude 8.18 +/- 3.55 micro V., latency 106.78 +/- 4.28 msec. 2. 32 X 32(25min). amplitude 8.48 +/- 5.99 micro V., latency 106.68 +/- 3.82 msec. 3. 64 X 64(12.5min). amplitude 7.79 +/- 3.68 micro V., latency 109.73 +/- 5.15 msec. 4. The change of latency between 32 X 32 and 64 X 64 check-size was statistically significant(p0.05). 6. The latency was most increased in 64 X 64(12.5min.) check-size and it was statistically significant(p<0.001).