Flashes and floaters

Floaters are small shapes that drift across vision. Flashes are brief sparks or streaks of light, often noticed in a dark room or at the edge of vision. They are common, but a sudden change can sometimes signal a retinal tear or detachment.

What do they look like?

Floaters may appear as dots, threads, cobwebs or squiggly lines. They tend to move when your eyes move and may be easier to see against a bright background such as a clear sky or white wall. Flashes can resemble brief lightning streaks or camera flashes.

Why do they happen?

The middle of the eye contains a clear gel called the vitreous. As we get older, this gel commonly becomes more liquid and can pull away from the retina; this is called posterior vitreous detachment. It often causes floaters and sometimes flashes. Most cases are not dangerous, but the pulling can occasionally create a retinal tear.

Who should be especially alert?

The risk of retinal tears or detachment is higher in people with high myopia, after eye surgery, after an eye injury, or when there is a family history of retinal detachment. Diabetes and inflammation inside the eye can also cause floaters. These factors do not mean that a problem will occur, but they are important to mention at an examination.

What will the eye doctor do?

A dilated eye examination lets the doctor look carefully at the retina, including its outer edges. The drops blur close vision and make light seem bright for several hours, so you may need help getting home. Additional imaging or an ultrasound scan may sometimes be needed.

Do floaters need treatment?

When the retina is healthy, floaters often become less noticeable with time and usually need no treatment. If a tear, detachment, inflammation, bleeding or another cause is found, that condition may need treatment. Procedures to remove longstanding floaters are reserved for selected situations because they have risks; discuss the balance carefully with your ophthalmologist.

This information cannot tell whether your own symptoms are harmless. New or sudden symptoms should be assessed promptly by an eye-care professional.