Photosensitivity
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Photosensitivity
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WHAT IS PHOTOSENSITIVE EPILEPSY? Flashing or flickering lights, or even geometric shapes or patterns can sometimes trigger seizures. This fairly rare condition is known as photosensitive epilepsy. HOW MANY PEOPLE ARE PHOTOSENSITIVE? Approximately 1:130 of the general population has epilepsy and of these only a few per cent may have seizures induced by flashing lights. Such sensitivity is commoner in children and adolescents and becomes less frequent with age, being very uncommon from the mid twenties onwards. HOW CAN I TELL IF I AM PHOTOSENSITIVE? Most people are aware of this. A standard EEG is done with photic stimulation i.e. flashing light and photosensitivity would usually be diagnosed at this stage. WHAT FACTORS MAY TRIGGER A SEIZURE IN SOMEONE WITH PHOTOSENSITIVE EPILEPSY? Common triggers include:
WHAT FREQUENCY OF FLASHING LIGHTS IS MOST LIKELY TO TRIGGER A SEIZURE? The frequency of flashing light, which is most likely to provoke seizures, varies from person to person. Generally, it is between the frequencies of 5-30 flashes per second (hertz). Some people, however, are photosensitive at higher flash frequencies. It is uncommon to have photosensitivity below 5 hertz. CAN VDUs CAUSE A PROBLEM IN PEOPLE WITH PHOTOSENSITIVITY? VDUs usually operate at a sufficiently high frequency that they do not provoke seizures, even in people with photosensitivity. Nevertheless, there are rare examples of people with sensitivity to high flash frequencies. In general terms, it is better if the lighting in the room is with an ordinary light rather than a fluorescent tube, as the flicker frequency from the fluorescent tube could potentially interact with the flicker frequency from the VDU. Probably, what matters more is what is showing on the VDU, in other words, is one looking at a flickering programme or changing geometric pattern on the screen? WHAT ABOUT COMPUTER GAMES?
Playing
computer games very rarely triggers epileptic seizures in people without a known
history of epilepsy. People who do have a seizure for the first time when
playing video games usually have an unrecognised susceptibility to seizures
triggered by flashing light, that is, most of them are photosensitive. CAN MY CHILD GO TO DISCOS? Ordinary coloured lights do not usually cause a problem if they do not flash, however, stroboscopic lights can trigger seizures, particularly if the background illumination is low and there may be other environmental triggers e.g. stress, excitement, tiredness etc. Some local authorities do have rules concerning the flash frequency of strobe lighting. The local Environmental Health Department will be able to give you more information on this. Unfortunately, if a person is known to be photosensitive it may be best to avoid stroboscopic lights. HELPFUL HINTS
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HELPLINE NUMBER: 08457 413774