Floaters and Flashes


Article updated and reviewed by Edward B. Feinberg, MD, MPH, Chair, Department of Ophthalmology, Boston University School of Medicine on May 2, 2005.

You may sometimes see small specks moving in your field of vision. These are called floaters. You may often see them when looking at a plain background, such as a blank wall or blue sky. You may at first mistake them for insects or dust floating in the air. They will appear to move as you move your eyes.

Floaters are actually tiny clumps of gel or cells in the vitreous, the clear jelly-like fluid that fills the back chamber in your eye.

When floaters first appear, they may be accompanied by what appears to be flashes of light. These are most easily seen when in the dark, but may be bright enough to be seen even when out in sunlight. The technical name for these flashing lights is “photopsia”.


While these objects look like they are in the front of your eye, they are actually floating inside. What you see are the shadows they cast on the retina, the nerve layer at the back of the eye that actually senses light. If you think of your eye as a camera, the retina would be the film in the camera. Floaters may have different shapes: little dots, circles, lines, clouds or cobwebs.

The new onset of floaters, particularly if accompanied by flashes, is a symptom which requires evaluation. New floaters or an increase in existing floaters may occur with shrinking of the vitreous gel away from the retina (called “posterior vitreous separation”). This usually is harmless, but in some people the vitreous may be firmly attached to the retina in one or more places, and here the retina may be torn as the vitreous pulls away. Torn retina will lead to retinal detachment if not corrected. If you have these symptoms, you should be seen by your ophthalmologist or your retina to be evaluated for possible torn areas.

While floaters may remain in the vision, many of them will fade over time and become less bothersome. Even if you have had floaters for some years, an ophthalmologist should be consulted if additional new floaters develop, or if flashes develop.

Flashing Lights

When the vitreous gel pulls on the retina, you may see what looks like flashing lights or lightning streaks. The flashes of light can appear on and off for several weeks or months. If you notice the new or sudden increased appearance of light flashes, it is advisable to consult an ophthalmologist to see if the retina has been torn.


Some people experience flashes of light that appear as jagged lines or "heat waves" in both eyes, often lasting 10 to 20 minutes. The light flashes of migraine generally last longer, have shapes, and often color while the flashes of vitreous separation are momentary and do not have recognizable shapes. Migraine flashes are usually caused by a spasm of blood vessels in the brain, which is called migraine.

If a headache follows the flashes, it is called a migraine headache. However, jagged lines or "heat waves" can occur without a headache. In this case, the light flashes are called ophthalmic migraine, or migraine without headache. (See Health Profile on Migraine).


When people reach middle age, the vitreous gel may start to thicken or shrink, forming clumps or strands inside the eye. The vitreous gel then pulls away from the retina, causing a posterior vitreous detachment. This is a common cause of floaters.

Posterior vitreous detachment is more common for people who:

  • Are nearsighted (have myopia)

  • Have undergone cataract operations

  • Have had inflammation inside the eye

  • Have a family history of retinal detachment


In general, floaters do not require any treatment. However, all people with new onset of floaters or flashes, or a sudden increase in existing flashes or floaters, should be checked for torn retina by an ophthalmologist. This requires an examination with dilated pupils using an instrument called an indirect ophthalmoscope. This examination requires a bright light and gentle pressure on the eyelid, but is not painful. The reason this is important is that if caught early, torn retina can be easily repaired in the office with a laser. If retinal detachment is allowed to develop, surgery becomes necessary.

Since most floaters will diminish with time, treatment for the floaters themselves is not needed. For severe cases where a large floater obstructs vision, a form of laser surgery has recently become available. Vitrectomy surgery, where the vitreous is removed and replaced with a clear fluid, is available for extensive and dense floaters which obstruct vision, but is a major eye operation and is not appropriate for floaters which are simply annoying, but do not obstruct vision.

Editorial review provided by VeriMed Healthcare Network.