Common Causes of Flashes of Light

21 Dec Common Causes of Flashes of Light

Updated by Mike Rosco, MD on 5/25.22 at 11:42 PM PST 

There are several causes of flashes. The most common cause is a posterior vitreous detachment (PVD), but a retinal tear, migraine and inflammation can also cause the same visual symptoms.

In other articles, a PVD and retinal tear have been well covered.

Flashes Due to Migraine

Though most are familiar with a traditional migraine and its symptoms (headache, sensitivity to light and loud sounds, nausea, etc.), it is less known that migraines can present visually and often without pain. These visual migraines yield a scintillating light pattern, which is often confused with flashes. The array of lights lasts under an hour (usually about 20 minutes) and migrates across the field of vision. For example, it may move from “right to left” over a 20 minute period.

This pattern generally resolves, though sometimes there may be a subsequent headache and/or other ocular symptoms. These, too, last only for a finite period of time.

Any migraine, or symptoms that you feel are migraine-related, should be evaluated by a doctor as there are other neurologic conditions that can produce the same symptoms. This diagnosis, while seemingly benign, should be made as a diagnosis of exclusion; that is, the doctor must make sure all other possibilities, such as tumor, are ruled out.

I often refer these types of cases to a neurologist or neuro-ophthalmologist to make sure I’m not missing something.

Flashes Related to Inflammation

Inflammation inside the eye is called uveitis, or iritis. It is very similar in nature to arthritis, another type of inflammation. Like arthritis of a joint, inflammation can occur just inside the eye.

Most commonly the inflammation is in the front of the eye, but on occasion, there can be types of inflammation affecting the retina. In these cases, symptoms can include flashes of light.

The best way to diagnose retinal or retinal vascular inflammation is with a dilated eye exam. This allows the ophthalmologist to visualize the retina in its entirety, evaluate its health, and detect any signs of inflammation or other abnormalities.

It is also probably prudent to seek the opinion of a retinal specialist in this case.

What Does This Mean?

In medicine, everything has a differential diagnosis. In other words, for a given symptom, it is a doctor’s responsibility to think of all the causes of that particular symptom.

Flashes of light are most often caused by a PVD or retinal tear, but could be caused by another condition, such as a migraine or inflammation.