Floaters and Flashes
Norman P. Blair, MD
Professor of Ophthalmology
What are floaters?
Floaters are dark dots, lines or particles that many people notice moving around in their vision as though floating in the eye. Floaters cast shadows on the retina, the light-sensitive tissue lining the inside of the back of the eye. The retina then sends visual signals to the brain, resulting in a visual image. Floaters come and go with eye movements, such as blinking. They follow eye movements, but lag behind and float to a halt shortly after the eyes stop moving. These images are most obvious when looking at a bright, uniform field of vision, such as a white wall or a clear sky. People may experience one or several floaters in one or both eyes. Floaters are not the same as the spots you see after looking at intense light such as the light from a flashbulb.
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Who gets floaters?
Most people see floaters some time during their lives. Many individuals notice some floaters even in their teens and 20s, and people who are nearsighted are particularly likely to have floaters at a younger age. Floaters tend to become more frequent as a person ages.
What causes floaters?
The majority of floaters are due to normal degenerative changes in the vitreous, the jelly-like substance that fills most of the center of the eye.
Sometimes people experience floaters because of a retinal tear without a retinal detachment. In that case, the tear usually can be treated with minor surgical procedures that can effectively prevent a retinal detachment. Some retinal tears do not require any treatment.
Some people have floaters caused by droplets of blood seeping from the abnormal growth of blood vessels. These people can suffer one or more hemorrhages into the eye that can severely affect their vision. Furthermore, abnormal blood vessel growth often leads to scar tissue that tends to shrink. This shrinkage can cause wrinkling, dragging, distortion, tearing and/or detachment of the retina. Minor surgical procedures usually can prevent these problems if the underlying problem is diagnosed early. If these problems become advanced, major eye surgery may be needed to prevent blindness. However, surgery sometimes is unable to completely reverse the damage caused by scar tissue.
No medications are available that are effective in treating most floaters.
Patients with floaters due to inflammatory eye diseases may be helped by medicines to treat the inflammation; however, the floaters may remain after the treatment. Although floaters can be bothersome, most people learn to ignore them.
Are flashes of light related to floaters?
Many patients suffer from both floaters and light flashes. Light flashes refer to the false sensation that light is flashing into the eye. Light flashes are bright and of very short duration. They usually are shaped like a line or an arc and may appear to shoot in a certain direction. Light flashes seem to occur in the side of the field of vision and can be seen even when the eyes are closed. Some of the same conditions that cause floaters also cause light flashes. These include the vitreous tugging on the retina or buildup of scar tissue in the eye.
What should I do if I have floaters?
Those who have had floaters a long time without much change recently should have an eye examination when convenient. However, certain symptoms are cause for immediate concern. Someone who has developed floaters for the first time or is certain their floaters have become worse or more numerous may have a new, potentially serious problem. A person who suddenly notices a large number of floaters, often like a shower of them, may have bleeding in the eye.
Other people may notice new floaters along with a cloudy area in the side field of vision in one eye. Often people describe this as a ‘curtain’ closing in on part of their vision. This may indicate that a retinal detachment is developing from a retinal tear. People with any of these symptoms should see an ophthalmologist right away. The evaluation of floaters should include examination of the retina and vitreous through dilated pupils, usually with gentle pressure to the eye to bring into view areas that are difficult to see. Early diagnosis and treatment may prevent serious problems and may improve the chance for preserving vision.