A study of the effect of color photo stimulation from a cathode-ray tube (CRT) display on photosensitive patients: The effect of alternating red-cyanflicker stimulation

Purpose: In an attempt to establish evidence for developing better guidelin es for the production of animation programs that would not induce photosens itive seizures in Japan, we evaluated the effects of red flicker, alternati ng red/cyan (complementary color to red) flicker stimuli, and of contrast b etween the red and cyan frames from a cathode-ray tube (CRT) display in pho tosensitive patients. Methods: We studied 35 photosensitive patients. They were exposed to seven types of flicker. The first three types were alternating red/cyan flicker ( R/C) with the luminance of cyan set at three different levels, high, equal, and low luminance (65, 20, and 16 cd/m(2), respectively) relative to the r ed (20 cd/m(2)). The following four types were red, cyan, yellow, and magen ta flicker stimuli. EEGs were recorded while the patients watched these sti muli on a CRT display. Results. Rates of photoparoxysmal response (PPR) provocation were 11.4, 13. 7, and 14.0% with high-, no- and low- contrast R/C flicker, respectively, a nd 3.7% with red flicker. The differences between red and each of the other R/C flicker stimuli were all statistically significant (p <0.05, 0.01, 0.0 1). No significant differences were found between the effects by each of th e three levels of contrast in alternating R/C flicker (p > 0.05). Conclusions: These findings suggest that alternating R/C flicker is more pr ovocative than simple red flicker, and that contrast between frames of diff erent colors may play some role in the effects of alternating flicker stimu li from a CRT display in photosensitive patients. Therefore, caution agains t the use of the combination of red and cyan, in addition to the red flicke r stimulus, should be included in any guidelines drawn up to prevent photos ensitive seizures.