A cataract is a clouding of the lens of the eye.
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 a person ages, proteins in the lens begin to break down. As a result, the lens becomes cloudy. What the eye sees may appear blurry. This condition is known as a cataract.
Factors that may speed cataract formation are:
In many cases, the cause of cataract is unknown.
Cataracts develop slowly and painlessly. Vision in the affected eye slowly gets worse.
Problems with seeing may include:
Cataracts lead to decreased vision, even in daylight. Most people with cataracts have similar changes in both eyes, though one eye may be worse than the other. Often there are only mild vision changes.
For early cataract, the eye doctor may recommend the following:
As vision gets worse, you may need to make changes around the home to avoid falls and injuries.
The only treatment for a cataract is surgery to remove it. If a cataract is not making it hard for you to see, surgery is usually not necessary. Cataracts do not harm the eye, so you can have surgery when you and your eye doctor decide it is right for you. Surgery is usually recommended when you cannot do normal activities such as driving, reading, or looking at computer or video screens, even with glasses.
Vision may not improve to 20/20 after cataract surgery if other eye diseases, such as macular degeneration, are present. The eye doctor (ophthalmologist) can often determine this in advance.
Early diagnosis and treatment are key to preventing permanent vision problems.
Although rare, a cataract that goes on to an advanced stage (called a hypermature cataract) can begin to leak into other parts of the eye. This may cause a painful form of glaucoma and inflammation inside the eye.
Call for an appointment with your health care provider if you have:
The best prevention involves controlling diseases that increase the risk of a cataract. Avoiding exposure to things that promote cataract formation can also help. For example, if you smoke, now is the time to quit. Also, when outdoors, wear sunglasses to protect your eyes from harmful UV rays.
Lens opacity; Age-related cataract
American Academy of Ophthalmology Cataract and Anterior Segment Panel. Preferred Practice Pattern Guidelines. Cataract in the Adult Eye. San Francisco, Ca: American Academy of Ophthalmology; 2011. Accessed August 29, 2013.
Zigler JS Jr, Datiles MB III. Pathogenesis of cataracts. In: Tasman W, Jaeger EA, eds. Duane's Ophthalmology on DVD-ROM – 2013 Edition. Philadelphia, Pa: Lippincott Williams & Wilkins; 2013:vol 1, 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. Philadelphia, Pa: Mosby Elsevier; 2008:chap 5.4.
Updated by: Franklin W. Lusby, MD, Ophthalmologist, Lusby Vision Institute, La Jolla, California. Also reviewed by David Zieve, MD, MHA, Bethanne Black, and the A.D.A.M. Editorial team.
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