Although photic-induced seizures frequently make the news because of their association with movies and video games, photosensitive epilepsy is actually quite rare. In fact, only approximately 3% to 5% of patients with epilepsy are photosensitive. Photosensitivity appears as an abnormal response to visual stimuli (known as a photoparoxysmal response) during an electroencephalogram (EEG). The presence of generalized spike-wave complexes during the photic stimulation phase of an EEG is considered diagnostic of primary generalized epilepsy. Photosensitivity is also of interest in a variety of rare diseases in which seizures are really an epiphenomenon of a degenerative disease (eg, progressive myoclonus epilepsy). We always perform photic stimulation as part of the patient’s EEG at our epilepsy center, and we see photosensitive epilepsy approximately once or twice per year. It is usually a type of primary (idiopathic, genetic) generalized epilepsy (eg, juvenile myoclonic epilepsy). In some cases, photosensitivity is detected on EEG, but the patient does not actually experience photosensitivity as a trigger in real life. 

According to the Epilepsy Foundation, the most common environmental hazards for photosensitive individuals include natural sunlight, artificial lights (especially flickering, malfunctioning fluorescent lighting), video games, and patterns from Venetian blinds. In addition, theaters, dance clubs, rock concerts, and even the Internet may trigger a seizure in such patients. Flashing lights between the frequencies of 5 and 30 flashes per second (Hertz) are the most likely to trigger seizures, but consensus statements recommend that photosensitive individuals should not be exposed to flashes greater than 3 per second. Other factors involved in photosensitivity include distance from the light source and color.

In general, photosensitive epilepsy should be managed like any other primary (idiopathic, genetic) generalized epilepsy: with broad-spectrum antiepileptic drugs. One nonpharmacologic treatment option for photosensitive epilepsy is available and consists of the use of blue-tinted eyeglass lenses that suppress photosensitive seizures by eliminating deep red colors, which have the longest wavelength. However, they can be difficult to find, they can be costly, and insurance coverage varies.