A Flash of Light

A flash of light

Erik van Rens, MD

Last week, I was asked to see a patient as an emergency work-in. She experienced sudden bright light flashes and floaters. Once she was in my office I had a chance to listen to her symptoms in more detail. She had a sudden onset of bright stroboscopic light sensations, followed by seeing dark spots. These lasted for about 15 minutes, after which they disappeared. Her symptoms turned out to be related to a fairly common phenomenon called ophthalmic migraines.

Most people associate migraines with severe headaches, but often eye symptoms are the only manifestation of a migraine attack. These are often very elaborate and can be very frightening, but are harmless. Patients often see kaleidoscopic patterns with bright colors in a strobe-like fashion. Sometimes these are followed by blind spots, usually starting in the periphery, but these can move to the center, blocking vision temporarily. Most attacks last less than 30 minutes, after which vision returns to normal. This patient could be reassured and she was glad it was not serious.

These flashes are quite different from the symptoms of a more dangerous phenomenon called vitreous detachment, when the vitreous gel that fills the eye cavity shrinks and pulls away from the adjacent retina. This is a process we all will go through, usually as we age, but often earlier in near sighted eyes. These light flashes are very brief, like a shooting star, and are mostly seen in dim or dark conditions upon eye movements. Ultimately they are followed by the sudden appearance of floaters, some of which are permanent.

A vitreous detachment happens only once, and is benign in most cases. Sometimes, however, it is the beginning of a bigger problem, when the gel cannot separate from the retina and tears it. This will lead to a progressive accumulation of fluid under the retina, forming a retinal detachment. Usually, the patient is aware of a progressive area of vision loss, that will get worse until all vision is lost. A tear in the retina can be treated with laser, and often will prevent the retina from detachment.

So, if a sudden onset of bright and brief light flashes, and floaters occur, visit an eye specialist as soon as possible, preferably with 24 hrs.