Floaters and Flashes

Floaters

The small specks, “bugs,” or clouds that you may sometimes see moving in your field of vision are called floaters. They are frequently visible when looking at a plain background, such as a blank wall or blue sky. These visual phenomena have been described for centuries; the ancient Romans called them muscae volitantes, or “flying flies,” because they can appear like small flies moving around in the air. Floaters are actually tiny clumps of gel or cellular debris within the vitreous, the clear, jellylike fluid that fills the inside cavity of the eye. Although these objects appear to be in front of the eye, they are actually floating in the fluid inside the eye and cast their shadows on the retina (the light-sensing inner layer of the eye). Moving your eyes back and forth and up and down creates currents within the vitreous capable of moving the floater outside your direct line of vision.

Causes

The vitreous gel degenerates in middle age, often forming microscopic clumps or strands within the eye. Vitreous shrinkage or condensation is called posterior vitreous detachment* and is a common cause of floaters. It also occurs frequently in nearsighted people or in those who have undergone cataract operations or YAG laser surgery. Occasionally, floaters result from inflammation within the eye or from crystal-like deposits that form in the vitreous gel. The appearance of floaters, whether in the form of little dots, circles, lines, clouds, or cobwebs, may be alarming, especially if they develop suddenly. However, they are usually nothing to be concerned about and simply result from the normal aging process.

Are Floaters Serious?

The vitreous covers the retinal surface. Occasionally the retina is torn when degenerating vitreous gel pulls away. This causes a small amount of bleeding in the eye, which may appear as a group of new floaters. A torn retina can be serious if it develops into a retinal detachment. Any sudden onset of many new floaters or flashes of light should be promptly evaluated by your eye doctor. Additional symptoms, especially loss of peripheral or side vision, require repeat ophthalmic examination.

Flashing Lights

When the vitreous gel, which fills the inside of the eye, rubs or pulls on the retina, it sometimes produces the illusion of flashing lights or lightning streaks. You may have experienced this; it is usually not cause for worry. On rare occasions, however, light flashes accompany a large number of new floaters and even a partial loss or shadowing of side vision. When this happens, prompt examination by an eye doctor is important to determine if a torn retina or retinal detachment has occurred. Flashes of light that appear as jagged lines or “heat waves,” often lasting 10 to 20 minutes and present in both eyes, are likely to be migraine caused by a spasm of blood vessels in the brain. If a headache follows, it is called a migraine headache. However, these jagged lines or “heat waves” commonly occur without a subsequent headache. In this case, the light flashes are referred to as ophthalmic migraine, or migraine without headache.