WHAT IS A CATARACT?

A cataract is not a skin-like growth or spread of tissue over the eye. Rather, it is a cloudy area in the natural lens of the eye. The normal lens is a clear, crystalline, discoid structure located in the eye just behind the pupil.

The eye is like a camera. Think of the lens of the eye as you would the lens of a camera which focuses images on the film at the back of the camera. The lens of the eye is responsible for focusing light clearly at the back of the eye on the retina, which is like the film in a camera.

When the internal structure of the lens becomes clouded, it is called a cataract. Cataracts decrease the amount of light that enters the eye. As a cataract develops, the clouding of the lens of the eye generally causes a gradual, painless decrease in vision. This clouding may vary from minimal, with little or no effect on vision, to maximal with severe reduction of vision.

Although cataract is a normal part of aging, there are also cataracts unrelated to age. Congenital cataracts may be present at birth. Traumatic cataracts are caused by injuries to the head or eye. Secondary cataracts may develop secondary to diseases such as diabetes mellitus or from medications such as steroids.

Most people affected have a cataract in each eye. However, one eye may be worse than the other because each cataract may develop at a different rate. The development of cataract is often very slow, so that the brain adapts to the reduction in vision. Some people with a cataract are not even aware of it. Their cataract may be small, on one side, or the changes in their vision may not bother them. Other people who have a cataract cannot see well enough to do the things they need or want to do.

THIS IS AN EXCERPT!

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Credits

This publication was made possible through the cooperation of the following members of the NAVH Medical Advisory Board: RONALD E. CARR, M.D. JONATHAN P. ELLANT, M.D. ANDREW S. FARBER, M.D. KENNETH B. JUECHTER, M.D. RICHARD B. ROSEN, M.D. RICHARD F. SPAIDE, M.D. FRANK J. WEINSTOCK, M.D.