OHSU

Casey Eye Institute at OHSU, Portland, Oregon

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Floaters and Flashes

What are floaters?

You may sometimes see small specks, strands or clouds moving in your field of vision. These are called floaters. You can often see them when looking at a plain background, like a blank wall, bright computer screen or blue sky. Floaters are actually tiny clumps of gel, cells, or collagen (protein) inside the vitreous, the jelly-like fluid that fills the inside of your eye. While these objects look like they are in front of your eye, they are actually floating inside it. What you see are the shadows they cast on the retina, the layer of nerve cells lining the back of they eye that senses light and allows you to see. Floaters can appear as different shapes, such as little dots, circles, lines, clouds, or cobwebs.

What causes floaters?

When people reach middle age, the vitreous gel may start to thicken or shrink, forming clumps or strands inside the eye. The vitreous gel pulls away from the back wall of the eye, causing a posterior vitreous detachment. This is a common cause of floaters. Posterior vitreous detachment is more common in people who: 

  • Are nearsighted 
  • Have undergone cataract operations
  • Have had YAG laser surgery of the eye
  • Have had inflammation inside the eye
  • Have had eye injury

The appearance of floaters may be alarming, especially if they develop very suddenly. You should contact your ophthalmologist (Eye MD) right away if you develop new floaters, especially if you are over 45 years old. Typically you will be seen on the same or the following day.

Are floaters ever serious?

In some instances, the retina can tear during a posterior vitreous detachment if the shrinking vitreous gel pulls at the retina (vitreoretinal traction). This pulling can sometimes occur at a retinal blood vessel and cause a small amount of bleeding in the eye that may appear as new floaters.  If the vitreoretinal traction creates bleeding but no retinal tear, no treatment is needed and your eye will gradually clear the blood from the eye.  If the vitreoretinal traction creates a retinal tear and the tear goes through a retinal blood vessel, treatment is usually required. 

A torn retina is always a serious problem, since it can lead to a retinal detachment. You should see your ophthalmologist as soon as possible if:

  • Even one new floater appears suddenly
  • You see sudden flashes of light

If you notice other symptoms, like the loss of side vision, you should see your ophthalmologist.Treatment of a retinal tear is typically done in the office using laser surgery or cryotherapy. Occasionally urgent surgery in the operating room is necessary.

Can floaters be removed?

Floaters may be a symptom of a tear in the retina, which is a serious problem. If a retinal tear is not treated, the retina may detach from the back of the eye. The only treatment for a detached retina is surgery. Other floaters are harmless and fade over time or become less bothersome, requiring no treatment. Surgery to remove floaters is almost never required. Vitamin therapy will not cause floaters to disappear. Even if you have had floaters for years, you should schedule an eye examination with your ophthalmologist is you suddenly notice new ones.  

What causes flashing lights?

When the vitreous gel rubs or pulls on the retina, you may see what look like flashing lights or lightning streaks. You may have experienced this same sensation if you have ever been hit in the eye and seen "stars". The flashes of light can appear off and on for several weeks or months. As we grow older, it is more common to experience flashes. If you notice the sudden appearance of light flashes, you should contact your ophthalmologist immediately in case the retina has been torn. Typically you will be seen on the same or the following day.

Migraine

Some people experience flashes of light that appear as jagged lines or "heat waves" in both eyes, often lasting 10 to 20 minutes. These types of flashes are usually caused by a spasm of blood vessels in the brain, which is called a 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. Contact your ophthalmologist if you experience these symptoms.

How are your eyes examined?

When an ophthalmologist examines your eyes, your pupils may be dilated (enlarged) with eye drops. During this examination, your ophthalmologist will carefully observe areas of your eye, including the retina and vitreous. If your eyes have been dilated, you will need to make arrangements for someone to drive you home afterward. Floaters and flashes of light become more common as we grow older. While not all floaters and flashes are serious, you should always have a medical eye examination by an ophthalmologist to make sure there has been no damage to your retina.