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flashes and floaters

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Normal eye

Alternative Names
vitreous opacities, spots in front of the eye, light flashes

Floaters are spots or lines that seem to float in a person's field of vision. The affected person often sees these accompanied by flashes of light coming from the side of the eye.

What is going on in the body?
The clear jelly-like material that fills the eyeball is called vitreous. With normal ageing, this gel may start to thicken and shrink. This may cause the gel to pull away from the internal lining of the eye. This condition is known as posterior vitreous detachment.

While some parts of the gel inside the eye thicken, other parts of the gel will liquefy. Floaters form when small clumps of protein settle out as the vitreous breaks down. When light enters the eye, it hits these small particles before reaching the retina. This is what a person perceives as spots in front of the eye.

Floaters are more common in people who are older or near-sighted. They also occur in people who have had cataract operations or laser surgery on the eye. Floaters can also follow inflammation inside the eye.

When floaters occur, a person will sometimes have quick, arc-shaped flashes of light out of the corner of the eye. These are often described as lightning flashes. Flashes may occur off and on for several weeks or even months. However, they usually disappear with time.

What are the signs and symptoms of the condition?
Floaters can come in many shapes. They can appear as small dots, circles, lines, veils or cobwebs. They are most apparent when looking at a blank wall or trying to read. A person may have several floaters or only a few. Usually floaters occur only in one eye at a time. Floaters are annoying but painless most of the time. They do not cause any loss of vision.

What are the causes and risks of the condition?
Floaters develop as a result of changes in the make up of the vitreous gel inside the eye. The gel may pull on or rub against the retina as the eye moves. The retina is the "film" on the back of the eye that helps transmit the things we see to the brain. When the gel pulls or rubs the retina, flashing lights or lightning streaks may occur in the person's vision. Flashes of light may also be a symptom of migraine headache. A person who experiences light flashes should be evaluated for migraines.

What can be done to prevent the condition?
Most cases of floaters and flashes of light cannot be prevented. They are a common and almost normal part of ageing.

How is the condition diagnosed?
If a person notices a new floater accompanied by light flashes, he or she should be checked by an opthalmologist. The opthalmologist will put drops in the eye to dilate or widen the pupil and carefully observe the retina and vitreous. It is important to rule out the possibility of a torn retina. Retinal tears can develop as the shrinking vitreous pulls away from the retina. This can cause small amount of bleeding from the tear to build up in the vitreous. This blood looks the same as a typical floater in the person's field of vision. An examination can reveal if the spots in front of the eye are harmless floaters or blood from a tear.

What are the long-term effects of the condition?
Floaters and flashes of light themselves cause no long-term effects. Flashes of light usually go away within a few weeks. Floaters can sometimes be noticed for years, but the brain usually learns to ignore the floaters and they become much less noticeable with time. An examination is important, however, to rule out other more serious causes.

For example, if undetected, a tear in the retina can sometimes lead to permanent loss of vision. Fluid can leak through the hole and accumulate under the retina, causing the retina to detach. When this happens, surgery is needed to correct the problem. However, if a retinal tear is found early, it can be sealed using a laser. This reduces the risk of detachment.

What are the risks to others?
This condition is not contagious and poses no risk to others.

What are the treatments for the condition?
Treatment is not needed or helpful if the retina is free of bleeding, tears and weak spots. Treatment is needed if a tear is found in the retina. This is most commonly repaired with a special argon laser by an opthalmologist. In some cases, surgery may be needed to reattach the retina.

What are the side effects of the treatments?
Laser treatment may irritate the eye or very rarely result in minor vision loss. Eye surgery may cause bleeding, infection or a reaction to any analgesics used. Vision loss is also possible, though rare.

What happens after treatment for the condition?
After an eye examination, the pupils often stay dilated for a few hours from the eye drops given. This makes the eyes sensitive to bright light and often causes blurry vision for things up close. This effect goes away within a few hours and is never permanent.

For regular floaters and flashes of light, no treatment is given and symptoms gradually lessen with time. Years later, people may still notice their floaters when tired or reading for long periods of time. After laser treatment or surgery, at least one or two follow up eye examinations are done. After that, no further treatment may be needed.

How is the condition monitored?
If a new group of floaters suddenly develops, an individual must be re-examined. This is necessary even if the person has had small floaters for years. Usually the floaters will appear suddenly in only one eye. An opthalmologist must do this examination with the pupils dilated.

Author: William Stevens, MD
Reviewer: HealthAnswers Australia Medical Review Panel
Editor: Dr David Taylor, Chief Medical Officer HealthAnswers Australia
Last Updated: 1/10/2001
Potential conflict of interest information for reviewers available on request

This website and article is not a substitute for independent professional advice. Nothing contained in this website is intended to be used as medical advice and it is not intended to be used to diagnose, treat, cure or prevent any disease, nor should it be used for therapeutic purposes or as a substitute for your own health professional's advice.  All Health and any associated parties do not accept any liability for any injury, loss or damage incurred by use of or reliance on the information.


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