Photosensitive Seizures
Photosensitive seizures are triggered by light, usually in cycling intermittently, or, for some people, by specific patterns or combinations/alternations of colours. Photosensitive seizures may be provoked by many sources: Sunlight passing through regularly spaced objects (trees, lampposts, etc.) as seen from a moving vehicle, stroboscopic lights, the flickering a television set, computer monitor or video game (especially when close to the screen or when the image is out of focus), card games, stationary patterns of striped lines, among others.
Photosensitive seizures are usually tonic-clonic, sometimes preceded by mild clonic jerking. Occurrence is predominantly in middle-childhood and, in most cases, diminishes towards adulthood. Approximately 88% of those who develop photosensitive epilepsy were previously affected by childhood and juvenile absence seizures or juvenile myoclonic seizures. In up to 50% of cases, photosensitive seizures may have also been experienced by close relatives of the patients, usually females and usually during childhood.
The occurrence of photosensitive seizures can be reduced significantly. For example, in more than 90% of people who experience photosensitive seizures, the stimulation of only one eye is far less apt to provoke a seizure than is the stimulation of both eyes. Covering one eye in the presence of potential triggers can significantly reduce the chances of having a seizure. Watching television on a small screen, maintaining a distance of at least a 2 metres from a large screen, using a remote control, and using TV "glasses" (a sheet of polarizer which enhances the contrast of the picture) with polaroid spectacles (worn by the viewer to duplicate the effect of monocular occlusion) may raise one's seizure threshold.
Sodium valproate (valproic acid) remains the drug of choice for controlling photosensitive seizures.
TV/Computer/Video Games
If seizures are triggered by flashing or flickering lights: - Ensure that the screen is in good working order.
- Watch television at a distance of at least 3 metres, at a 45 degree angle.
- To reduce contrast and glare, always have lights on in the room, situated above and behind the viewer.
- Some people report finding sunglasses helpful.
- When using a modern computer, you can adjust the blink rate of the cursor.
- When using a computer, try to use a modern monitor. They flicker less and "refresh" faster.
Or use an LCD screen which doesn't flicker.
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