Photosensitive epilepsy

Photosensitive epilepsy is where someone has seizures that are triggered by flashing or flickering lights, or patterns. Any type of seizure could be triggered but tonic-clonic seizures are the most common.

There are 2 groups of people who have photosensitive epilepsy:

1. People who only have seizures triggered by flashing or flickering lights, or patterns. This is sometimes called pure photosensitivity
2. People who have seizures triggered by flashing or flickering lights or patterns but also have seizures at other times

Flashing and flickering lights

Different people will be affected by lights at different flash or flicker rates. Lights that flash or flicker between 16 and 25 times a second are the most likely to trigger seizures. But some people are sensitive to rates as low as 3 or as high as 60 a second.

Patterns

Different people will be affected by different types of pattern. Those patterns with a high contrast or some that move are more likely to trigger seizures.

How common is photosensitive epilepsy?

Around 3 in every 100 people with epilepsy have photosensitive epilepsy. If someone else in your family has photosensitive epilepsy, you are more likely to have it too. And if someone in your family has juvenile myoclonic epilepsy, you are also at higher risk of having photosensitive epilepsy.

There are many types of epilepsy and photosensitive epilepsy is most common in the following:

• Juvenile myoclonic epilepsy
• Childhood absence epilepsy
• West syndrome
• Lennox Gastaut syndrome
• Juvenile absence epilepsy
• Dravet syndrome

Is photosensitive epilepsy more common at a particular age?

Most people who develop photosensitive epilepsy are aged between 7 and 19 years old. But a small number of people who develop epilepsy as adults, also have photosensitive seizures. And some people who had photosensitive epilepsy as children, will continue having photosensitive seizures when they become adults. Females are more likely to have photosensitive epilepsy than males.

Are there tests that can show if I have photosensitive epilepsy?

Your doctor might ask you to have an electroencephalogram (EEG) test to see if you have photosensitive epilepsy. The EEG records the electrical signals from your brain on an EEG machine. During the test, you will be asked to look at some flashing lights, to see whether your brainwave patterns change. If they do, it may mean you have photosensitive epilepsy.

What is the treatment for photosensitive epilepsy?

The most common way to treat photosensitive epilepsy is with epilepsy medicines. This is to lower the risk of having a seizure. To reduce the risk further, try to avoid looking at things that you know can trigger a seizure.

If you find yourself coming across something that might trigger a seizure without warning:

• Don’t close your eyes (this could cause a flicker effect)
• Do cover one eye with the palm of your hand straight away
• Do turn away from the possible trigger

Doing these things reduces the number of brain cells that could be stimulated and in that way the risk of a seizure happening is reduced.

Find out more about possible seizure triggers for people with photosensitive epilepsy.

If you would like to see this information with references, visit the Advice and Information references section of our website or contact our Epilepsy Action freephone helpline on 0808 800 5050.