A cataract is a clouding of the eye’s lens. Over time, cataracts worsen and interfere with vision. Formation of cataracts is painless, but the loss of vision can limit a person’s ability to perform daily tasks and live independently.

Cataracts are the most frequent cause of blindness in the world and one of the leading causes of loss of vision in the United States. More than half of Americans will have developed a cataract by age 80, according to the National Eye Institute (NEI).

Risk factors and causes include old age, exposure to ultraviolet light or radiation, diabetes, smoking, eye surgery, eye trauma, congenital eye conditions, certain medications and high blood pressure. The NEI estimates that people with diabetes are 50 percent more likely than nondiabetics to develop cataracts.

Cataracts usually develop slowly. They can affect one or both eyes but do not spread from one eye to another. Their primary symptom is clouded, blurred or dimmed vision. Patients may also experience poor night vision, halos around lights and increased sensitivity to light.

In early stages, cataracts can be dealt with by using sunglasses, stronger prescription glasses and brighter lights. When they worsen enough to interfere with daily activities, the only treatment is surgical removal of the lens. Vision is restored through a plastic intraocular lens (IOL) the surgeon inserts into the eye. Cataract surgery has a high rate of success.

Prevention of cataracts includes protecting the eyes from the sun, not smoking, controlling blood pressure and possibly eating a diet rich in antioxidants and other nutrients.