Influence of Red Light and Pattern on Photic Driving

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Abstract
The photic drivings (PD) in response to the following visual stimuli were studied in 108 cases, of which 84 (78%) were epileptics; ages ranged from 5-57 yr old. An intermittent photic stimulation (IPS) of 5 cycles[c]/s by a stroboscopic light was given to the subjects with eyes closed and open. Following these stimuli, red-flicker and flickering-pattern of 5 c/s and 20 cd/m2 were given successively to the subjects with eyes open using a visual stimulator. The PD evoked by IPS to the eyes closed and those by red-flicker were similar in the wave form and amplitude. In most cases both stimuli failed to evoke apparent PD (over 25 .mu.V in amplitude, i.e., in 81% and 72%, respectively. IPS to the eyes open and flickering-pattern showed comparable effects in evoking PD; they evoked high amplitude PD (over 50 .mu.V in amplitude) with a frequency of 19% by the former and 28% by the latter. In 95 out of 108 cases, both IPS to the eyes closed and red-flicker failed to evoke apparent PD. In rare cases, IPS to eyes closed evoked high amplitude PD; in 7 out of these 8 cases, red-flicker also evoked high amplitude PD. In 18 out of 20 cases in which high amplitude PD were evoked by IPS to the eyes open, flickering-pattern was also effective in evoking high amplitude PD. Based on these findings, similarities between IPS to the eyes closed and red-flicker, and similarities between IPS to the eyes open and flickering-pattern in evoking PD are discussed. Flickering-pattern and red-flicker are superior to IPS to the eyes open and closed, respectively, for examining the low frequency PD.

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