Cataracts - Description

The lens is positioned near the front of the eyeball. It is protected by the cornea, which covers the front of the eyeball. The purpose of the lens is to focus the light waves that enter the eye. Muscles around the lens can change the shape of the lens. In this way, objects both close at hand and far away can be brought into focus.

The lens is made up of about 35 percent protein and 65 percent water. Proteins are chemical compounds found in all cells. As people grow older, the chemicals present in their eyes may change. Proteins may break down, water may seep out of the eye, or other changes may occur. One consequence of such changes is the formation of cataracts.

Cataracts are common in older people. They are so common that they are regarded as a normal part of the aging process. For those between the ages of 50 and 65, the chance of having a cataract is about 50 percent. Beyond the age of 70, the risk rises to about 70 percent.

The transparent outer coating on the front of the eyeball.
A transparent oval body located near the front of the eye that focuses light waves.
Chemicals that are found in every cell in the human body and carry out many essential functions.
A thin layer of tissue at the back of the eyeball on which light waves are focused and then transmitted to the brain by way of the optic nerve.
Naturally occurring chemicals that help reduce inflammation, pain, and swelling.

Cataracts also occur in young people, but are much less common. For example, the lens may be injured by some foreign object, which may lead to the formation of a cataract. Cataracts are also caused by certain diseases, such as diabetes mellitus (see diabetes mellitus entry).

Cataracts generally have little or no effect on vision in their early stages. As they develop, they can lead to vision problems and, eventually, blindness may result.

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