What are floaters and flashing lights? - Sparks & Feros Optometrists

What are floaters and flashing lights?

Floaters are dark specks in the form of dots, circles, lines or cobwebs that appear to move across the field of vision. They are particularly noticeable when one is looking at a light-coloured background such as a clear sky or a white wall. Floaters come in many sizes and numbers, and they appear to move when the eye looks in different directions.


The inside of the eye is filled with a clear, gel-like substance called the vitreous. The retina is a thin, light-sensitive tissue that covers the inside back portion of the eye and works like the film in a camera. Floaters are small clumps of gel that form in the vitreous. Although they appear to be in front of the eye, they are actually floating in the vitreous and are seen as shadows by the retina.

The appearance of floaters may cause concern, especially if they develop suddenly. However, they are usually of little importance. The vitreous pushs up against the retina like air pushs on the wall of a balloon. As we get into our fifties and up the vitreous shrinks and often separates from the retina. By the age of 50 years the vitreous has separated from the retina in about 50% of all people. As the vitreous detaches, it causes floaters. At first the floaters may be quite annoying, but the brain gradually learns to ignore them, and after several months they are hardly noticed. 

If you get flashes that are followed by a shower of dots that do not move or go away you shoud see your optometrist that same day.


Floaters may sometimes interfere with clear vision, often when one is reading. If a floater appears directly in your line of vision, move your eye around; this will cause the vitreous to swirl around and will move the floater out of your way. Looking up and down rather than back and forth will cause different currents inside the eye and may be more effective in getting the floater out of the way.


Flashing lights are the sensation of lights going on and off, noticed particularly off to one side. They tend to occur in only one eye at a time and persist even when the eye is closed.


The vitreous, a clear gel-like substance that fills the inside of the eye, sometimes pulls or tugs on the retina. This pulling causes the appearance of flashing lights or lightning streaks, though there is no flashing light actually present. This same sensation sometimes occurs when one is hit in the eye and sees "stars".

This commonly happens as people grow older and usually is not cause for alarm.

Flashes of light that appear as jagged lines, last 10 to 50 minutes and are present in both eyes are likely migraine caused by a spasm of blood vessels in the brain. Sometimes this occurs only in one eye.  If a headache follows, it is called a migraine headache. If there is no subsequent headache, the light flashes are referred to as ophthalmic migraine, or migraine without headache. If your symptoms fully resolve in 1 hour than it is likely not a retinal problem.


Most of the time the vitreous separates from the retina without causing any problems. Occasionally, flashing lights are associated with many new floaters and even a blacking out of part of the field of vision. If this occurs, immediate examination by an eye doctor is important to determine whether a retinal tear or retinal detachment has developed. Retinal tears require treatment to prevent the retina from detaching. Retinal detachment is a serious problem that must be repaired surgically.

In summary, floaters and flashing lights usually do not indicate any serious eye problem. If a large number develop or if they seem to be much worse over a period of time, an examination by an eye doctor is recommended. The examination involves careful observation of the retina and vitreous.

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