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Eye Floaters and Flashes

What are Eye Floaters?

Eye floaters are often described as spots, specks, strings, or cobwebs in your field of vision. They often appear to drift around with eye movement, and when you try to look at them, they move quickly away. While annoying, eye floaters are very common and usually are not cause for alarm. Most people have floaters and learn to ignore them. They are usually not noticed unless they become more numerous or more prominent. Floaters are most visible when looking at a bright background such as a white piece of paper, white wall, or the bright blue sky.

What causes Floaters?

Floaters are found in the vitreous, a gel-like substance that fills the back of the eye. Floaters can be present since birth, from normal vitreous proteins or embryonic debris (particles remaining in the vitreous after growth of the eye was completed). And floaters can occur with age, as the vitreous slowly shrinks. As the vitreous shrinks, it begins to liquefy and have a waterier center. Small pieces of the vitreous can break loose within the inner portion of the eye. Undissolved gel particles can float around in the liquid center and cast shadows on the retina. These shadows are perceived as floaters. They can be distracting at first, but will usually tend to settle at the bottom of the eye, becoming less bothersome once they are out of your line of sight. They do not go away completely.

Floaters are most often caused by the normal aging process. They can also be a result of other diseases or conditions.

Posterior Vitreous Detachment (PVD)

As the eye develops, the vitreous gel fills the inside of the back of the eye and presses against the retina and attaches to the surface of the retina. Over time, the vitreous becomes more liquefied in the center. The central, waterier vitreous cannot support the weight of the heavier, more peripheral vitreous gel. The peripheral vitreous gel then collapses into the central, liquefied vitreous, detaching from the retina. Eye floaters resulting from a posterior vitreous detachment are then concentrated in the more liquid vitreous found in the interior center of the eye. Thankfully, most of these PVDs do not lead to a torn or detached retina. Light flashes during this process mean that traction is being applied to your retina while the PVD takes place. Once the vitreous finally detaches and pressure on the retina is eased, the light flashes should gradually subside. A small percentage of people may develop a tear or detachment of the retina due to the vitreous tugging on the retina.

Many will notice a new unusually large floater called a “Weiss ring.” This floater is the result of a piece of condensed vitreous gel that was attached around the optic nerve prior to the vitreous separation from the retina. This should become less noticeable with time.

Inflammation in the back of the eye

Posterior uveitis is inflammation of the uveal layers in the back of the eye. This condition can cause the release of inflammatory material into the vitreous. This can be perceived as floaters. Uveitis can be caused by infection or inflammatory diseases.

Blood in the vitreous

Red blood cells in the vitreous may also be seen as floaters. Bleeding into the vitreous can be as a result of diabetes, hypertension, blocked blood vessels and injury.

Retinal Tear or Detachment

Retinal tears occur when the vitreous tugs on the retina with enough force to tear it. Fluid may accumulate behind the retina and cause it to further separate from the back of the eye. When the retina is tugged, torn or detached from the back of the eye, a flash or flicker of light commonly is noticed. Depending on the extent of the traction, tear or detachment, these flashes of light might be short-lived or continue indefinitely until the retina is repaired. There is usually a large increase in floaters due to pigment liberated from the retinal tissue. A retinal detachment is a serious condition and should always be considered an emergency. An untreated retinal detachment can cause permanent vision loss.

Eye surgeries or medications

Certain medications that are injected into the vitreous can cause air bubbles to form. Until these bubbles are absorbed, they may look like floaters.

Risk Factors:

  • Increasing age

  • Nearsightedness

  • Eye trauma

  • Cataract surgery

  • Diabetes

  • Eye Inflammation


For most floaters, particularly those associated with aging changes, there is no recommended treatment. In very rare instances, when the floaters are so dense and numerous that they significantly affect vision, a vitrectomy can be performed. A vitrectomy is a surgery which removes the vitreous gel from the eye. The vitreous is then replaced with an artificial solution which mimics the original vitreous. This surgery carries numerous risks including retinal detachment, tears, and formation of cataract. Most of the time surgeons are reluctant to recommend this surgery unless the floaters are severe.

See a doctor ASAP when:

  • Large increase in the number of floaters

  • Sudden onset of new floaters

  • Flashes of light in the same eye as the floaters

  • Dark areas on the side of your vision, or a “curtain” over your vision


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