STEADY-STATE VISUAL-EVOKED POTENTIALS TO COMPUTER MONITOR FLICKER

In the present study, steady-state visual evoked potentials (S-VEP) in response to amplitude-modulated light from a computer monitor (colour sVGA, 15-inch tube) have been examined. S-VEPs to computer monitors w ith different refresh rates (60 Hz or 72 Hz) and screen brightness (65 cd/m(2) or 6 cd/m(2)) were recorded in 13 subjects with normal or cor rected-to-normal vision. EEG samples were amplified, averaged and stor ed using Cadwell Excel EMG-EP recorder and a regression model was appl ied for the amplitude analysis. The mean values of S-VEP amplitude at 60 Hz were found to be significantly higher at 60 Hz refresh rate vs. 72 Hz (F-1,F-12 = 14.1; P = 0.003). Effect of screen brightness (F-2,F -24 = 6.5; e = 0.62; P = 0.00075) as well as the interaction effect of refresh rate and screen brightness (F-2,F-24 = 11.6; P = 0.0003) were also found to be significant. Data obtained show that the characteris tics of amplitude-modulated light from a computer monitor (frequency, brightness, waveform) are sufficient to elicit S-VEP, and the influenc e is not only restricted to the peripheral divisions of the visual sys tem as it was shown earlier, but also extends to the central brain str uctures. (C) 1998 Elsevier Science B.V.