Blog #140: Blinking Lights, Flashes and Epilepsy

 

 

 

     Light flashes, light patterns and color changes can provoke seizures in 3% of people with epilepsy. This is known as photosensitive epilepsy.¹ Is this you? Photosensitive epilepsy is more common in children and adolescents, especially those with generalized epilepsy and certain syndromes as juvenile myoclonic epilepsy. It lessens as children age. Relatively few cases last into their mid-twenties.

 

     Many people are not aware they are sensitive to flickering lights or to certain patterns until they have a seizure. In some individuals, their seizures occur only when triggered by certain photic, or light conditions. And in some individuals this sensitivity may never progress to develop epilepsy. Some people find they are sensitive to light exposure because they develop headache, nausea, or dizziness induced by this light exposure. They do not develop seizures and they do not have epilepsy. Brain scans usually are normal.

 

     Light triggers include flickering or rolling images on television and smartphone screens and computer monitors, emergency vehicles, intense strobe lights like visual fire alarms, natural flickering light off shimmering water, sunlight flickering through tree leaves while driving, and through venetian blinds and certain visual patterns, especially stripes of contrasting colors. Not all these visual stimuli trigger seizures. Other factors are important, e.g., frequency of the flash, the brightness of the flash, its contrast with the background, your distance from the light source, the wavelength of the light and whether your eyes are open or closed. The resulting effect of the frequency or speed of the inducing flashes varies from person to person. The frequency of light triggers generally varies between 5 to 30 flashes per second.

 

     If flashing lights are uncomfortable for you a routine EEG can help find out why. The EEG includes a period of flashing strobe lights at various frequencies positioned in front of closed eyes as you lie on the bed in the EEG lab. An abnormal EEG response to various frequencies of flashes indicates the presence of photosensitivity which is an electroencephalography (EEG) phenomenon or the photoparoxysmal response. This does not mean you have epilepsy. If you are found to have this photosensitivity, altering your daily activities can help to avoid your physical symptoms, as avoiding intense videogame playing.

 

     Helpful tips to consider if you have photosensitivity include covering only one eye and looking away. Closing both eyes will not help. Watch TV in a well-lit room to reduce light-contrasts, sit far from the screen, wear polarized sunglasses while viewing TV to reduce glare. Follow similar guides when playing video games. Do not close and open eyes in front of the videogame as blinking may facilitate seizures in sensitive people. Cover and alternate covering the right and the left eye while playing at regular intervals. If you perceive strange or unusual feelings or if body jerks occur, stop playing.

 

     Regarding computer monitors use one that is flicker-free (LCD or flat screen). Use a monitor glare-guard. Wear non-glare glasses to reduce glare. Take frequent breaks.

 

     Strobe lights are to be avoided if you can. If you can’t, cover one eye and turn away.

 

     Visually induced seizures remain significant public health hazards; they warrant public education.

 

     I hope that this blog allows you to identify certain phenomena you experience but could not explain before.

 

1.     Wirrell E, Hernandez A. Photosensitivity and Seizures published by the Epilepsy Foundation: September 30, 2019.

 Lance Fogan, M.D. is Clinical Professor of Neurology at the David Geffen School of Medicine at UCLA. His hard-hitting emotional family medical drama, “DINGS, is told from a mother’s point of view. “DINGS” is his first novel. Aside from acclamation on internet bookstore sites, U.S. Report of Books, and the Hollywood Book Review, DINGS has been advertised in a recent Publishers Weekly, New York Times Book Review and the Los Angeles Times Calendar section. DINGS teaches epilepsy and is now available in eBook, audiobook, and soft and hard cover editions.