Definition

A cataract is a cloudiness in the lens of the eye, which is normally clear and transparent. The cloudiness caused by a cataract may eventually lead to decreased vision and blindness.

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...