Cataracts

Definition
A cataract is a clouding of the normally clear and transparent lens of the eye. It is not a tumor, a new growth of skin or tissue over the eye, but a fogging of the lens itself.

Description
Normally, the lens of the eye is clear. When a cataract develops, the lens becomes cloudy, similar to a frosted window. Located near the front of the eye, the lens focuses light on the retina at the back of the eye. Light passes through it to produce a sharp image on the retina. When a cataract forms, the lens can become so opaque and unclear that light cannot easily be transmitted to the retina. Often, however, a cataract covers only a small part of the lens and if sight is not greatly impaired, there is no need to remove the cataract. If a large portion of the lens becomes cloudy, sight can be partially or completely lost until the cataract is removed. There are many misconceptions about cataracts. For instance, cataracts do not spread from eye to eye, though they may develop in both eyes at the same time. A cataract is not a film visible on the outside of the eye, is not caused from overuse of the eyes, and using the eye does not make it worse. Cataracts usually develop gradually over many years; rarely over a few months. Finally, cataracts are not related to cancer, and having a cataract does not mean a patient will be permanently blind. Depending on the size and location of the cloudy areas in a lens, a person may or may not be aware that a cataract is developing. If the cataract is located on the outer edge of the lens, no change may be noticed in vision, but if the cloudiness is located near the center of the lens, it usually interferes with clear sight. As cataracts develop, there may be hazy, fuzzy and blurred vision. Double vision may also occur when a cataract is beginning to form. The eyes may be more sensitive to light and glare, making night driving difficult. With cataracts, there may be a need to change eyeglass prescriptions frequently. As the cataract worsens, stronger glasses are no longer able to improve sight. It may help to hold objects closer to the eye when reading or doing close-up work. The pupil, which is normally black, may undergo noticeable color changes and appear to be yellowish or white.