Most serious retinal problems that require surgery are caused by problems with the vitreous. The vitreous is much like the clear "white" of an egg and it fills the central cavity of the eye. The vitreous is attached to the retina. It is most strongly attached to the retina at the sides of the eye. It is also attached in the back part of the eye to the optic nerve, the macula, and the large retinal blood vessels.

Posterior Vitreous Detachment (PVD)

As a person ages, the thick vitreous gel becomes less like a gel and more like a fluid. Small pockets of fluid form within the gel of the vitreous. As the eyeball moves, the liquified vitreous moves around inside the vitreous cavity. Because of this movement of fluid, the vitreous begins to pull on the retina. With time, the vitreous can pull free and separate from the retina and optic nerve in the back (or posterior) part of the eye. This is called a "posterior vitreous detachment" (PVD). This kind of detachment happens eventually in most people and only infrequently causes a problem.

Flashes and Floaters

When a person develops a posterior vitreous detachment, flashes of light or large spots in the vision may occur. The flashes of light are caused by the tugging of the vitreous where it is attached to the retina. As the vitreous pulls on the retina, the brain interprets this pulling as flashes of light. As it liquifies and pulls away from the retina, the vitreous becomes somewhat condensed and stringy and forms strands. The patient can see these strands and strings; they appear as spots, small circles, or irregular fine threads in the vision. They seem to float and are therefore called "floaters".