Photosensitive epilepsy is a type of reflex epilepsy (RE) where seizures are caused by a specific trigger. Photosensitive epilepsy, is a common form of RE, affecting about five percent of people with epilepsy. Photosensitive epilepsy is not the same as epilepsy syndrome, which is a seizure disorder causing spontaneous seizures.
Common triggers for photosensitive epilepsy include flashing lights from TV, computer games, concerts, or moving light patterns. How bad the seizures are and how long they last can be influenced by the frequency, type, and color of the stimulus.
Photosensitive epilepsy is typically a genetic condition and more often affects younger women.
Photosensitive epilepsy is triggered by light-based stimulation and/or different patterns or colors, such as stripes and polka dots.
Photosensitive epilepsy typically causes a generalized seizure, which can affect the prefrontal, frontopolar, occipital, and supplementary motor areas of the brain. Focal seizures, on the other hand, typically only start in one part of the brain and only affect that related area in the body. Focal seizures from photosensitivity are much less common than generalized seizures.
There are several types of generalized seizures, each with their own symptoms:
Tonic-clonic seizures (sometimes referred to as grand mal seizures) cause your body, arms, and legs to seize up and straighten out, shake or tremor, and then go limp and relaxed. After the seizure, you may feel fatigued, have slurred speech, blurred vision, or dizziness and a headache.
- Tonic seizures, which cause your limbs to suddenly stiffen, typically last for about 20 seconds.
- Clonic seizures cause the muscles to jerk around rapidly and uncontrollably.
- Myoclonic seizures cause specific muscle groups to spasm and jerk periodically throughout the day.
- Absence seizures (sometimes referred to as petit mal seizures) cause you to briefly lose consciousness, although you may stay upright and appear conscious. After an absence seizure ends (usually within about 30 seconds), you may have no recollection of what happened.
- Atonic seizures cause your muscles to go completely limp and unresponsive.
Myoclonic jerks, generalized tonic-clonic seizures, and absence seizures are the most common symptoms of photosensitive epilepsy. Loss or impairment of consciousness or motor symptoms like involuntary eye movement (e.g., blinking, fluttering, widening, and flickering) occur in approximately 75 percent of cases. Other symptoms during or after a seizure caused by photosensitivity include dizziness, pain, nausea, anxiety, and other uncomfortable sensations.
A photosensitive epilepsy seizure can happen even if someone doesn’t have a seizure disorder. It’s important to understand what can trigger an episode.
The primary trigger for a photosensitive epilepsy seizure is a light-based source such as:
- Light from the screens of TVs, computers, cell phones, or movie theaters
- Flickering lights such as strobe lights, disco lights, or faulty fluorescent bulbs
- Bright or reflected light, such as reflected sunlight off a mirror, window, or snowbank
- High-contrast colors or patterns, such as stripes and dots
- Light passing through partially obscured window coverings such as blinds
Moving objects can also trigger a seizure, such as escalators, ceiling fans, propellers, and helicopter blades.
Other factors can influence the likelihood of having a seizure caused by photosensitive epilepsy:
- Whether your eyes were open, closed, or partially closed when the stimulus happened
- The contrast and brightness of the colors or light
- The speed and frequency of the movement or pattern (typically 8–30 flashes per second can increase the risk of seizure)
- The distance from the trigger (the closer you are, the greater the risk)
- The color of the trigger (red can be more stimulating than blue
If you’ve experienced any seizure, you should seek medical attention as soon as possible. If you suspect you may be photosensitive, your health care provider may suggest that you undergo testing and monitoring with an electroencephalogram (EEG). An EEG measures brain activity in response to certain stimuli in a controlled environment.
If you’re regularly exposed to common photosensitive epilepsy triggers, talk to your health care provider about how to reduce your risk of having a seizure.
How do you know if you have photosensitive epilepsy and not just visual discomfort?
Photosensitive epilepsy is more severe than feeling visual discomfort from a light source. Visual discomfort can happen when you see something that your eyes and brain haven’t had time to process. Visual discomfort can cause you to feel eye strain, headaches, dizziness, and nausea. In these instances, look away as soon as you feel discomfort.
In the case of a seizure from photosensitive epilepsy, on the other hand, you lose control of muscle function and thought processes until the seizure is over.
There is nothing you can do to stop a seizure once it has started. However, there are ways that you can reduce the risk of having a seizure caused by photosensitivity and treat symptoms related to photosensitive epilepsy.
If you have photosensitive epilepsy, try to avoid known triggers. Take extra precautions if you experience insomnia or fatigue, and avoid highly stimulating activities like playing video games.
Polarized sunglasses are said to be effective at preventing photosensitive epilepsy seizures if the trigger is caused by natural light sources.
If these preventative measures don’t work or if you have another seizure syndrome, your health care provider may prescribe antiepileptic drugs. Medication such as valproate, vigabatrin, or levetiracetam may help regulate the condition and reduce the risk or severity of seizures.
The best way to prevent a photosensitive epilepsy seizure is by avoiding triggers. It can be hard to get rid of triggers altogether, but some light sources offer less risk than others. Modern liquid crystal display (LCD) screens are less likely to trigger seizures than light tube-based screens. Plasma screens typically have higher contrast and brightness, which can increase the risk of seizure.
Some general tips for preventing a seizure caused by photosensitivity include:
- Sit far away from the screen and at an angle where the screen doesn’t take up your whole field of vision.
- Watch TV, movies, or video games in a well-lit room.
- Take regular breaks by closing your eyes or stepping away from the screen. Pause what you’re doing and avoid looking at the screen if you’re fast-forwarding or rewinding.
- Decrease the brightness and contrast settings of your TV or computer screen.
- Check for any seizure warnings on the packages of video games or movies.
- Cover one eye if you’re exposed to a possible trigger.
Some studies suggest that wearing polaroid sunglasses or blue-toned lenses may be effective at reducing the risk of seizures. These types of sunglasses can suppress the prevalence of flickering dot patterns, which can trigger a seizure in people with photosensitive epilepsy.
Now that you know what photosensitive epilepsy is, you can take the necessary steps to try to prevent seizures if you have the condition. Typically, photosensitive epilepsy occurs in young people and is not related to any other seizure syndrome. Talk to your health care provider if you think you may have photosensitive epilepsy or if you’ve had any seizures or seizure symptoms.