Cataract Fact Sheet

What is it?

A cataract forms when the lens of the eye becomes cloudy, probably because of changes in the proteins of the lens. Cataracts are extremely common; more than half of Americans age 65 and older have a cataract, and it is thought that nearly everyone will develop one if they live long enough. Cataracts take a long time to develop to the point that they are a serious problem for your vision. There are several types of cataract; the most common is called nuclear cataract because it affects the inside of the lens. Another common form is cortical cataract, in which the outside of the lens becomes cloudy.
Symptoms

The main symptoms of a cataract are blurred, dulled vision in the affected eye, which cannot be corrected by wearing stronger glasses or contact lenses. In addition, you may find you need a brighter light for reading. Increased sensitivity to glare may also be a problem.

The cataract animation shows what the world might look like to a person with progressive symptoms of cataract.

Prevention

Smoking greatly increases the chance of getting nuclear cataract, the most common type in the US. So, the most effective way to lower your risk of cataract is not to smoke. (Note that this is the same advice given in the section on age-related macular degeneration, or AMD, a far more serious eye disease.) People with diabetes, even young people, often develop cataracts. Formation of diabetic cataracts can be slowed by keeping blood sugar under tight control. Even better, of course, is to maintain a normal weight; then you probably won’t get type-2 diabetes (by far the most common form of diabetes in the US) in the first place.


The scientific evidence for other preventive measures is weak, but suggestive. Sunlight exposure may have a borderline effect on hastening the formation of cortical cataract. Antioxidants (especially vitamin C) and carotenoids in the diet may slow down the progression of some types of cataract, but the evidence is conflicting. The prudent thing to do is to eat several portions a day of fruits and vegetables, and to wear sunglasses and brimmed hats in bright sunlight. Even if it doesn’t reduce your risk of cataract, this behavior will help protect you against heart disease, skin cancer, and probably AMD.

Treatment

Cataract is the only truly curable eye disease (other than wearing glasses or contact lenses to correct refractive errors like myopia). Cataract surgery is the most common operation performed in the US; it is rapid, safe, and nearly always it is completely successful. A cataract needs to be removed only if it interferes with your vision enough to prevent you from driving, reading, or other essential activities. A "ripe" cataract can easily be extracted by an eye surgeon. Usually an artificial lens (called an intraocular lens, or IOL) is implanted in the eye during surgery, so that people no longer need to wear "coke-bottle" glasses.

For more information about cataract and the surgery for it, see:

http://www.nei.nih.gov/health/cataract/cataract_facts.asp.

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