Photosensitive Epilepsy

According to the World Health Organisation Epilepsy is ‘a chronic noncommunicable disease of the brain that affects around 50 million people worldwide. It is characterized by recurrent seizures, which are brief episodes of involuntary movement that may involve a part of the body (partial) or the entire body (generalized) and are sometimes accompanied by loss of consciousness’

Photosensitive epilepsy is a type of epilepsy in which seizures can be triggered by flashing / flickering lights, or high contrast patterns. It is estimated that 3% of people with epilepsy are photosensitive.

From an accessibility perspective this means that content providers should take care when uploading content which could trigger seizures in people with photosensitive epilepsy.  Current guidelines recommend that content could be an issue if it:

  • Contains anything that flashes more than 3 times in any second long period

Current guidelines also recommend

  • Reducing contrast for flashing content
  • Reducing the number of flashes even if they do not violate thresholds
  • Providing a way to stop any flashing content before it begins (content controls to start and stop audio visual content)
  • Freezing the image momentarily if there are 3 flashes in 1 second