Sometimes flashing or flickering lights, geometric shapes or patterns can trigger seizures. This is a fairly rare condition. Approximately one to two per cent of the population has epilepsy. Only a small portion of this population is sensitive to this stimulation. Photosensitive seizures are usually tonic-clonic, but other types of seizures may be triggered by photic stimulation.
A diagnosis of photosensitive epilepsy is confirmed by a standard EEG with photic stimulation (flashing lights). Some people may have seizures triggered by flourescent lights and computer or TV monitors, even though their EEG results do not support a diagnosis of photosensitive epilepsy.
Sodium valproate and clonazepam have been shown to be effective in treating photosensitive epilepsy.

Common Triggers

• Faulty fluorescent lights that flicker
• Television or computer monitors
• Television and movies, and their associated special effects
• Video games/computer graphics, especially fast paced screen changes, bright screens and flickering patterns
• Light reflected on water, glass, or broken up by trees, fences, buildings, etc., as through a car window
• Stroboscopic lights and flashing lights on emergency vehicles
• Some people are sensitive to various geometric shapes or patterns (stripes or checkered patterns)
• Car headlights and other lights at night

In general, more than five flashes per second or more than three screen changes per second may pose a risk to people with photosensitive epilepsy. This effect seems to diminish when flash rates exceed 70 to 100 flashes per second.

Dealing with Photosensitive Epilepsy

• Watch television in a well lit room.
• Avoid watching poorly tuned television channels or faulty TVs.
• Use a remote control to change channels and avoid going too close to the screen.
• Modern computer monitors refresh faster and flicker less. LCD monitors do not flicker.
• Limit your exposure to fluorescent lighting.
• If you are suddenly exposed to a flickering/flashing light, try covering or shutting one eye. It may reduce the effects you normally experience.
• Fatigue may increase the risk of photosensitive seizures.
• Wearing polarized sunglasses (blue or green) provide some protection outdoors. (Ordinary sunglasses offer no protection.)

Employees with photosensitive epilepsy should determine if they need any accommodation to help them fulfill their assigned job duties. Refer to the Accommodation section for suggestions.