Cataract - Overview
Lens opacity; Age-related cataract
Definition of Cataract:
A cataract is a clouding of the lens of the eye.
This article focuses on cataracts in adults. For information on cataracts in children, see: Congenital cataracts
Causes, incidence, and risk factors:
The lens of the eye is normally clear. It acts like the lens on a camera, focusing light as it passes to the back of the eye.
Until a person is around age 45, the shape of the lens is able to change. This allows the lens to focus on an object, whether it is close or far away.
As we age, proteins in the lens begin to break down and the lens becomes cloudy. What the eye sees may appear blurry. This condition is known as a cataract.
Factors that may speed up cataract formation are:
- Eye inflammation
- Eye injury
- Family history of cataracts
- Long-term use of corticosteroids (taken by mouth) or certain other medications
- Radiation exposure
- Surgery for another eye problem
- Too much exposure to ultraviolet light (sunlight)
In many cases, the cause of cataract is unknown.
- Reviewed last on: 8/31/2010
- Franklin W. Lusby, MD, Ophthalmologist, Lusby Vision Institute, La Jolla, California. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
Zigler Jr. JS, Datiles III MB. Pathogenesis of cataracts. In: Tasman W, Jaeger EA, eds. Duane's Ophthalmology. 15th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2009:chap 72B.
Howes FW. Indications for lens surgery/indications for application of different lens surgery techniques. In: Yanoff M, Duker JS, eds. Ophthalmology. 3rd ed. St. Louis, Mo: Mosby Elsevier; 2008:chap 5.4.
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