The effect of high-frequency light flicker on pattern-reversal and steady-state visual evoked potentials in healthy subjects

Purpose We investigated the effect of screen technology on visual evoked potentials (VEPs) by comparing a standard Cathode Ray Tube (CRT) screen with two Liquid Crystal Display (LCD) Light-Emitting Diode (LED) screens with differing levels of latency and high-frequency backlight flicker. Methods All screens were calibrated to emit the same luminance and color composition. 19 young healthy subjects underwent VEP recording using checkerboard patterns with check widths of 0.26 degrees (º), 0.51º and 1.03º. Pattern Reversal VEPs (prVEPs) were recorded from occipital (O1, Oz, and O2) electrodes referenced to a frontal electrode (Fz), and Steady State VEPs (SSVEPs) were recorded using a standard International 10–20 electrode cap. Results prVEP peak latencies were prolonged and amplitudes were slightly larger with LCD screens compared to the CRT screen, though the high-flicker LCD screen had slightly shorter peak latencies. Pattern-reversal SSVEP at 10 and 12 reversals/s entrained cortical activity to a comparable level across all screens, with no representation of high-frequency backlight flicker or its subharmonics detected in the SSVEP signal. Conclusion Backlight flicker characteristics, timing jitter and latency affects VEP. Significance These findings suggest that backlight flicker, timing jitter and latency should be considered when selecting LCD screens for clinical VEP recordings.