Black or gray specks, strings or cobwebs that typically drift about when you move your eyes and appear to dart away when you look at them directly are known as floaters.

They may be most noticeable when you look at a plain, bright background, like the blue sky or a white wall.

People who need glasses to see distance (nearsighted) are more likely to get floaters. They’re also more common in adults older than age 50, as well as in people who’ve experienced eye trauma or inflammation inside the eye.

The presence of a few long-standing floaters usually isn’t a cause for concern. Most are caused by age-related changes that occur as the jellylike substance (vitreous) inside your eye becomes more liquid. When this happens, tiny fibers within the vitreous tend to clump and can cast tiny shadows on your retina.

Although usually harmless, not all floaters are nonthreatening clumps of vitreous, so it’s a good idea to have any new floaters examined with a dilated eye exam by an optometrist or an ophthalmologist.

Contact an eye specialist immediately if you notice a sudden increase in floaters in one eye. In particular, seek prompt attention if you also see light flashes or lose your peripheral vision. This change may signal that the retina has pulled away, or is pulling away, from the back of your eye (retinal detachment). Detachment usually occurs over about a week. A retina with a hole or tear can be treated with laser treatment or surgery. If left untreated, full detachment can lead to vision loss in the affected eye.

Rarely, eye floaters can impair your vision, which can be treated by surgery to remove the vitreous and replace it with a solution to help your eye maintain shape. However, risks include bleeding and retinal tears, and the surgery may not remove all of the floaters. Another treatment is laser therapy in which a laser breaks up floaters, making them less noticeable.