2017 Volume 66 Issue 3 Pages 179-183
Visual evoked potentials (VEPs) are electrical responses in the primary visual cortex to visual stimulation. Although a cathode ray tube (CRT) monitor is often used to record a VEP in hospitals, liquid crystal display (LCD) monitors are affordable and recently replacing CRT monitors in the general market. The purpose of this study was to compare the latency and amplitude of VEP elicited by a CRT monitor with those elicited by LCD monitors in normal subjects. We used a CRT monitor and two LCD monitors with response times of 5 ms and 12 ms, respectively. We standardized the average luminance in each monitor. The latencies of N75, P100 and N145 elicited by both LCD monitors were significantly longer than those elicited by the CRT monitor (p < 0.01). The amplitudes were not significantly different among the three monitors. The delayed latencies elicited by the LCD monitors may be caused by a response time for black to turn to white and for white to black. On the other hand, the standardization of luminance contributed to obtaining similar amplitudes among all monitors. When we substitute a CRT monitor for an LCD monitor, the reference range needs to be updated.
