It is unusual for modern computer and television screens to trigger seizures. But it could happen, depending on the screen or the images that you are looking at.
Types of screen
There are different types of screen which can be used with a computer or when watching television. These include cathode ray tube screens, liquid crystal screens and plasma screens.
Cathode ray tube screens
Cathode ray tube (CRT) screens use tubes to create a picture. They are the older style of screen and are large and bulky. They are prone to flickering.
Modern CRT screens have a ‘refresh’ rate of 100 times each second (100Hz). These are unlikely to trigger a seizure, unless they are faulty.
Older CRT screens may refresh the picture at a rate which could trigger a seizure, especially if you sit near to the screen.
Liquid crystal screens
Liquid crystal display (LCD), light-emitting diode (LED) and thin-film transistor (TFT-LCD) screens all use liquid crystals to create a picture. They are all thin and have a flat screen.
Liquid crystal screens don’t flicker and are far less likely to trigger a seizure than CRT screens. However, the risk of having a seizure is not removed entirely, because they are brighter and have more contrasting colours than CRT screens. Contrasting colours increase the risk of seizures.
Plasma display panel (PDP) screens use tiny gas plasma cells to create a picture. They are thin and have a flat screen.
Plasma screens don’t flicker and are far less likely to trigger a seizure than CRT screens. The risk of having a seizure is not removed entirely, because plasma screens are brighter and have more contrasting colours than both CRT and liquid crystal screens. Contrasting colours increase the risk of seizures.
Choosing a screen
If you have photosensitive epilepsy, the current advice is to use an LCD screen. This is the type that carries the least risk of triggering a seizure.
Images on computer and television screens
The content you look at on a computer or television could trigger seizures if it has any of the following.
- Flashing or flickering lights
For example, when there are a lot of press photographers on television, all using a camera flash at the same time.
- Rapidly changing images
For example, these may appear when you are playing on a games console.
- Contrasting or moving patterns
For example, these may appear when you are watching video clips on a computer.
In the UK, there are guidelines for TV broadcasters to restrict the use of images that may cause a problem for people with photosensitive epilepsy. They should also give a warning if a programme has images that could trigger a seizure. However, there is no guarantee that a warning will always be given.
General safety suggestions for watching television or using a computer
- Make sure that the room is well lit.
- Have a lamp lit close to the screen.
- If possible, use a liquid crystal or plasma screen and reduce the brightness setting.
- If you use a CRT screen, make sure that the ‘refresh’ rate is set to greater than 70Hz. Also make sure that the screen is in good working order.
- Consider covering one eye with something that won’t let light through, such as an eye patch. This will reduce the number of brain cells that are stimulated by any flashing or flickering. For most people with photosensitive epilepsy, this will minimise the risk of having a seizure.
- If you have any discomfort, such as dizziness, blurred vision, loss of awareness or muscle twitching, stop looking at the screen immediately.
- Take frequent breaks for rest and food.
Safety suggestions specific to watching television
- Sit or stand at a distance of at least 2.5 metres (8 feet) from the television.
- Use the remote control wherever possible - from a safe distance - to adjust the television or to change channels.
- If you have to go near the television, cover one of your eyes with the palm of your hand.
3D images do not have a higher risk of triggering a seizure than 2D images, as long as you follow these safety guidelines.
- Remove 3D glasses before you stop watching something in 3D. This is because the glasses flicker for a few seconds when 3D is turned off. This flickering could trigger a seizure.
- If you are using an active shutter 3D system, the television should not be placed near a window. When it is daylight, the active shutter glasses produce a flicker in the window. This could trigger a seizure.
Epilepsy Action would like to thank Professor G F A Harding, Emeritus Professor of Clinical Neurophysiology, Aston University and also Professor Stefano Seri, Professor of Clinical Neurophysiology at Aston University and Consultant at the Birmingham Children’s Hospital NHS Foundation Trust for their contribution to this information.
This information has been produced under the terms of The Information Standard.
Updated March 2012To be reviewed March 2015