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
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
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
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.