INTERMITTENTLY flashing light is used clinically as a technique for producing abnormal (paroxysmal) rhythms in the electroencephalogram to aid in the diagnosis of epilepsy. Recently, reports have appeared in which this technique is used to trigger seizures in the convulsive treatment of psychotic patients (photoshock). It is also used as a research tool in clinical investigation.1 With such wide use of this stimulus, it seems wise at this time to report upon certain untoward effects of intermittent light that can occur to patient and researcher alike. The vivid subjective visual sensations induced by this means (Prevost-Fechner-Benham effect) have long been known.2 Walter and Walter,3 in 1949, noted that the immediate effects of intermittent photic stimulation may, in addition, include sensations of spinning, vertigo, fear, and visceral disturbances.
In our own laboratory during the past three years my colleagues and I have observed the effects of intermittent photic
ULETT GA. FLICKER SICKNESS. AMA Arch Ophthalmol. 1953;50(6):685-687. doi:10.1001/archopht.1953.00920030696002