A cataract is a clouding on the lens of the eye that interferes with vision.
The natural lens of the eye is located behind the pupil and iris. It should be clear. The lens refracts, or bends, light rays coming into the eye. This causes the light rays to focus on the retina. Any clouding of the lens will interfere with normal vision. Clouding occurs when proteins in the lens change and group together. These changes are part of normal aging.
Most cataracts develop during the normal course of aging. Proteins in the lens change and group together. Over time, the lens becomes firmer or more opaque. Infants and children can have cataracts, although this is rare. Following are some of the other causes of cataracts: