Posterior Vitreous Separation

longmont eye doctor depicts normal vision

posterior vitreous separation


Most of the eye's interior is filled with vitreous, a gel-like substance that helps the eye maintain a round shape. There are millions of fine fibers intertwined within the vitreous that are attached to the surface of the retina. As we age, the vitreous slowly shrinks, and these fine fibers pull on the retinal surface. Usually the fibers break, allowing the vitreous to separate and shrink from the retina.

Most of the eye's interior behind the lens and back to the retina is filled with vitreous, a gel-like substance that helps the eye maintain a round shape. Within the vitreous many fine fibers are intertwined and attached to the retina and the optic nerve. With age, the vitreous begins to thin and there is a separation of the watery elements from the fibrous components. It also begins to shrink and pull away or separate from the retina. This is called posterior vitreous separation, which is common and usually harmless. It can also separate from the retina due to changes in the eye from diabetes, blocked blood vessels, inflammations or due to a sudden blow to the eye.

Posterior vitreous separation frequently causes the symptoms of floaters and flashing lights, but infrequently causes a loss of vision. It should not be confused with retinal detachment, which is a very serious condition requiring immediate attention. It can however, precede a retinal tear and/or detachment.


There are two common symptoms of posterior vitreous separation:

  1. Flashes of light: When the vitreous separates from the retina, it can pull or tug lightly on the surface of the retina. The retina responds to this pulling by sending the sensation of a flash of light to the brain. These flashes of light are usually the most noticeable symptom of a posterior vitreous separation and may last only a moment or may last intermittently for several months. Each time a flash of light occurs it is an indication that the retina has been tugged upon. In a small number of people, the vitreous can pull hard enough on the surface of the retina that a retinal tear occurs which can subsequently lead to a retinal detachment.
  2. Sensation of floaters: The clumping of the fibers that are normally present within the vitreous sometimes causes the sensation of floaters within a person’s vision. Floaters are also due to the presence of normal cells on the back surface of the gel. As a separation occurs, blood vessels bleed into the vitreous gel. These strands and cells block the passage of light to the retina resulting in small shadows and the sensation of black floaters. Floaters can consist of cobwebs, rings, dots, streaks or a combination of any of these possibly indicating a retinal tear or retinal detachment.

Usually the appearance of new floaters or light flashes does not indicate any serious eye problem. However, the only way to ensure that the floaters or flashes are not symptomatic of a more serious problem, is to have your retina examined.

Since abnormal conditions of the eye can cause the symptoms of flashes and floaters, Dr. Robinson performs a complete examination at the initial onset of flashers and floaters to determine the cause. Subsequent examinations should also be performed if the flashers or floaters should change or become worse. Dr. Robinson will determine if there is a need for any subsequent examinations.