MAYO CLINIC

DEAR MAYO CLINIC: I've noticed several dark spots and cobweb-like strings in my vision. Is this something to be concerned about?

ANSWER: Dark spots such as those you describe may be floaters. These black or gray specks, strings or cobwebs typically drift about when you move your eyes and appear to dart away when you look at them directly. 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 way, 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, at which time your eye doctor may recommend treatment. That can involve surgery to remove the vitreous and replace it with a solution to help your eye maintain shape. However, there are risks, including bleeding and retinal tears, and the surgery may not remove all of the floaters. Another treatment used infrequently for impaired vision caused by eye floaters is laser therapy. This treatment uses a laser to break up the floaters, making them less noticeable. Laser therapy risks still are not completely known.

As with any eye problem, if you are concerned about eye floaters, it's best to discuss your situation with an eye care professional, who will conduct a complete eye exam. By examining the back of your eyes and the vitreous, he or she can determine the cause of the floaters. (adapted from Mayo Clinic Health Letter) - Amir Khan, M.D., Ophthalmology, Mayo Clinic, Rochester, Minn.