Cataracts are spots that form on the lens of an eye, eventually clouding the lens, interfering with vision and, in extreme cases, causing blindness. The lens helps the eye to focus light. Light rays reflected from objects first strike the cornea, a transparent covering of the eyeball, and then travel through the lens. The lens bends the light rays to form an image on the back of the eye, the retina. Good vision depends on these various components functioning together. When a person develops cataracts, symptoms can include blurry vision, glare sensitivity, fading of colors, and poor night vision.

Cataracts are often associated with aging and are thus called senile cataracts. However cataracts can be caused by diabetes, parathyroid gland abnormalities, Down's syndrome and other conditions. Recent studies show that exposure to ultraviolet radiation in sunlight and artificial light during childhood may have an effect on the formation...