A cataract is cloudiness of the lens in the eye, causing blurred vision. Typically, cataracts affect both eyes, but usually one eye is more severely affected. In most cases, cataracts are a result of normal aging; most people over about 65 have some cataract formation.
However, they may also sometimes be present from birth or may be due to factors such as eye injury, certain eye diseases such as uveitis (inflammation of various internal eye structures), prolonged exposure to sunlight, long-term corticosteroid treatment, or diabetes. Cataracts are also common in people with Down syndrome.
Smoking increases the risk of developing cataracts. Typically, cataracts develop over months or years.
They cause only visual symptoms, such as blurred vision, altered color vision, and seeing haloes around bright lights.
Treatment is with surgery to remove the natural lens and, in most cases, replace it with an artificial one. This usually improves vision significantly, although some people still need to wear glasses or contact lenses afterward