We all sometimes have seemingly minor symptoms that we rationalize away. We tell ourselves “oh that’s nothing” or “it’ll get better by itself”. Flashing lights is one of those symptoms that may seem unimportant but may be significant. I will address some of the more common causes.
Flashing lights usually lasts only a matter of seconds and happens only occasionally. Both of these characteristics can lull us into ignoring it. There are several significant processes that can cause this. Vitreous separation is probably the most common. The large cavity of the eye is filled with a jelly like substance called vitreous. When we are born it is attached to the back surface of the eye, the retina. As we age the vitreous shrinks. So at some point it has to separate from the retina. This can irritate the retina and cause flashing lights. It can also result in floating spots in our vision. This is because the vitreous surface that was against the retina is now floating in the center of the eye casting a shadow. Most of the time (99+%) this does not cause a problem. Rarely the vitreous separation can tear a hole in the retina which can lead to a retinal detachment, a very serious condition. Unfortunately a retinal tear cannot be diagnosed by symptoms only. An exam is the only way to tell. So, the only way to insure that a tear has not developed is to have an exam as soon as possible following the onset of flashes or floaters.
Other conditions that can cause flashing lights are blood vessel narrowing to the eye or area in brain controlling vision. This usually occurs over age 60 and can be a precursor to stroke. A carotid ultrasound can diagnose blood vessel narrowing due to hardening of the arteries (atherosclerosis). Sometimes the narrowing might be due to an inflammatory condition called Giant Cell Arteritis. This is more rare but potentially devastating and usually requires blood tests and possibly a biopsy to diagnose.
Another cause of flashing lights could be migraine headaches. This is a less serious but still annoying condition. Most migraine sufferers begin having symptoms between teenage and mid twenties. Since the onset is rarer in older people the new onset of symptoms after age 40 should be tested to make sure one of the more serious cause of flashing lights is not the cause.
So don’t just ignore those flashing lights. It is worth getting an eye exam to make sure there is nothing serious going on that may cause not only vision problems but general health concerns as well