Cataracts

A cataract is a clouding of the eye's natural lens, which lies behind the iris and the pupil. The lens works much like a camera lens, focusing light onto the retina at the back of the eye.

Cataract surgery is very successful in restoring vision. In fact, it is the most frequently performed surgery in the United States, with over 1.5 million cataract surgeries done each year. Nine out of 10 people who have cataract surgery regain very good vision, somewhere between 20/20 and 20/40.

Cataracts are classified as one of three types:

• A nuclear cataract is most commonly seen as it forms. This cataract forms in the nucleus, the center of the lens, and is due to natural aging changes.
   
• A cortical cataract, which forms in the lens cortex, gradually extends its spokes from the outside of the lens to the center. Many diabetics develop cortical cataracts.
   
• A subcapsular cataract begins at the back of the lens. People with diabetes, high farsightedness, retinitis pigmentosa or those taking high doses of steroids may develop a subcapsular cataract.

By Judith Lee and Gretchyn Bailey; reviewed by Dr. Vance Thompson