Epilepsy is a condition featured by frequent seizure episodes, as a result of abnormal electrical fluctuations in the brain cells. Photosensitive epilepsy is a type of epilepsy in which fits occur in an individual due to exposure to variable typical patterns of light.
The Common Triggers Of Photosensitive Epilepsy
Stimuli that trigger photosensitive epilepsy may be in the form of:
- Intense flashes of light
- Flickering lights
- Moving light patterns
- ‘Striped’ or ‘chequered’ colored graphics
These visual stimuli excite the neurons and cause abrupt seizure episodes to occur.
The Mechanism Behind Photosensitive Epilepsy
The basic cause for the seizure is the hyper-excitation of brain cells due to visual signals. Varying yet typical light patterns trigger fluctuations in the electrical activity of the neurons. Abnormally high electrical discharges are spread over wide areas of the brain, resulting in either ‘localized’ or ‘generalized tonic-clonic’ type of contractions in the muscles, making the body stiff.
Some Important Facts About Photosensitive Epilepsy
- Characteristically, bright lights, high contrast lights, intense flashes and flickering light patterns provoke seizure episodes.
- Different persons may be susceptible to this condition at different wavelengths of light.
- Certain typical patterns like ‘bright-colored stripes over a contrasting background’, or common color combinations like red and blue may also be triggers.
- Some patients experience photosensitive epilepsy with their eyes open, while some experience it with their eyes closed.
- If flickers of light cover the whole field of vision, chances of a seizure episode are high. In this case, lower exposure to such flickers lessens the risk.
- Different people are susceptible to the seizures at different frequencies of flickering light. Some patients may be sensitive to as low as 3 flickers per second, while some may require as high as 60 flickers per second, for the seizures to occur. Most of the patients are sensitive to a frequency between 16 – 25 per second.
Who Can Be Affected By This Condition?
Here are some details on who can suffer from the condition.
- Of all the cases of epilepsy, about 3 to 5 % amount to the photosensitive type.
- Children and adolescents (aged between 7 and 19 years) are most susceptible to photosensitive epilepsy.
- Children who watch TV or play video games for hours together may be affected at a higher rate.
- Those who have a family history of photosensitive epilepsy also face a higher risk.
Typical Light Patterns That Provoke Seizures
Light From Television Screens
Television has been the most common cause behind the precipitation of photosensitive epilepsy. Sitting close to the TV or watching it in a dark room can be a seizure-provoking factor. TV monitors emit light in the form of flickers. These flickers are not normally perceived by the human eye as their frequency falls outside the range that a human eye can note.
Light From Computer Screens
Working on computers with bright and high contrast displays can cause photosensitive epilepsy.
Prolonged staring at video game screens is also one of the primary causes.
Strobe Lights From Ambulances Or Police Vans
Staring at the alternating bright flashes that are emanated by strobe lights of ambulances or police vans can bring about a seizure.
Lights In Movie Theatres
Bright lights projected over the screen in movie theaters which create a contrast with the dark surroundings, also cause photosensitive epilepsy.
The bright glare of headlights of vehicles passing by, while driving at night is another major factor.
Exposure to multiple camera flashes at the same time can trigger seizures.
Also, individuals with this problem should watch out for sunshine creeping through trees, and bright flashes of sunlight that are reflected off mirrors or the surface of water.
Welding Flames Or Firecrackers
Looking directly at the flames during welding or continuously watching bursting firecrackers can trigger a seizure.
Exposure to the overhead lights while passing through tunnels is another major cause.
Visually taking in brightly colored or high contrast garments, particularly with striped or chequered patterns, can trigger seizures.
Diagnosis Of Photosensitive Epilepsy
If you have ever experienced a seizure due to prolonged exposure to bright lights or while watching TV, you might have photosensitive epilepsy.
When you consult a doctor for photosensitive epilepsy, you are likely to be tested for any change in the pattern of your EEG (Electroencephalogram) waves. The doctor will ask you to look at a rapidly flickering source of light, and while you do so, the electrical activity of your brain will be recorded.
Certain typical changes in your EEG waves will help confirm the diagnosis of photosensitive epilepsy. The presence of photosensitive epilepsy symptoms will also be noted.
Measures To Prevent Photosensitive Epilepsy
If you have photosensitive epilepsy, here are some ways to avoid further episodes of the same:
- Maintain a minimum distance of 8 feet while watching TV. For computer screens, this distance should be at least 2 feet. This helps reduce the effect of flickering lights of high intensity, high brightness, or heavy contrast.
- Choose flat screen models for TVs and computers, as they produce fewer flickers.
- Set a low brightness level while watching TV or while working on a computer. The contrast level should also be kept low, especially in dark surroundings.
- Lessen the time you spend working in front of such monitors if you have had seizures in past.
- If such exposure is unavoidable, close one eye during the exposure. This reduces the level of excitation required to exceed the threshold for seizures to occur.
- Use polarized glasses or goggles while going into areas with bright and high contrast light flickers.
- Take regular medication. Never alter the dose of the drug or its schedule without the doctor’s advice.
Photosensitive epilepsy can be prevented by taking strict precautions, particularly while watching television and working on computers. Doctors will advise you to limit your exposure to the most common light patterns that trigger this condition, especially if you have experienced it in the past. With a little bit of care, you can protect your eyes from the source of such epileptic seizures.