This study describes a 16-year old boy that had an epileptic seizure after repeated exposure to disco lights. Since then he had jerks in the shoulders and eyelids when exposed to strong lights.
His monozygous twin brother had none of these symptoms, but he had not been exposed to the particular strong lights.
Both twins had generalized epileptic responses in their EEGs provoked by visual stimulation, but only in the affected boy was the response was accompanied by clinical symptoms.
This study suggests permanent effects of repeated exposures to strong lights in a visual sensitive person. Epilepsy can be primed in certain rodent models by repeated stimulations, but the effect has not been described in men or in primates until now.
Press Release by Epilepsy Research UK