Cataract
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Definition
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
Alternative Names
Lens opacity; Age-related cataract
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:
Diabetes
Eye inflammation
Eye injury
Family history of cataracts
Long-term use of corticosteroids (taken by mouth) or certain other medications
Radiation exposure
Smoking
Surgery for another eye problem
Too much exposure to ultraviolet light (sunlight)
In many cases, the cause of cataract is unknown.
References
Zigler JS Jr, Datiles MB III. Pathogenesis of cataracts. In: Tasman W, Jaeger EA, eds. Duane's Ophthalmology. 15th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2011: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.
Review Date: 9/16/2011
Reviewed By: 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.
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. Copyright 2004 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
Alternative Names
Lens opacity; Age-related cataract
Symptoms
Adult cataracts develop slowly and painlessly. Vision in the affected eye or eyes slowly gets worse.
- Mild clouding of the lens often occurs after age 60, but it may not cause any vision problems.
- By age 75, most people have cataracts that affect their vision.
Visual problems may include the following changes:
- Being sensitive to glare
- Cloudy, fuzzy, foggy, or filmy vision
- Difficulty seeing at night or in dim light
- Double vision
- Loss of color intensity
- Problems seeing shapes against a background or the difference between shades of colors
- Seeing halos around lights
Cataracts generally lead to decreased vision, even in daylight. Most people with cataracts have similar changes in both eyes, although one eye may be worse than the other. Many people with this condition have only mild vision changes.
Other symptoms may include:
- Frequent changes in eyeglass prescription
Signs and tests
A standard eye exam and slit-lamp examination are used to diagnose cataracts. Other diagnostic tests are rarely needed, except to rule out other possible causes of poor vision.
References
Zigler JS Jr, Datiles MB III. Pathogenesis of cataracts. In: Tasman W, Jaeger EA, eds. Duane's Ophthalmology. 15th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2011: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.
Review Date: 9/16/2011
Reviewed By: 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.
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. Copyright 2004 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
Alternative Names
Lens opacity; Age-related cataract
Treatment
The following may help people who have an early cataract:
Better eyeglasses
Better lighting
Magnifying lenses
Sunglasses
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. Surgery is done if you cannot perform normal activities, such as driving, reading, or looking at computer or video screens, even with glasses.
If a cataract is not bothersome, surgery is usually not necessary. Cataracts usually do not harm your eye, so you can have surgery when it is convenient for you.
However, some people may have additional eye problems, such as diabetic retinopathy, that cannot be treated without first having cataract surgery.
For information on surgery, see: Cataract surgery
Expectations (prognosis)
Vision may not improve to 20/20 after cataract surgery if other eye diseases, such as macular degeneration, are present. Ophthalmologists can usually, but not always, determine this in advance.
Complications
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.
Calling your health care provider
Call for an appointment with your health care provider if you have:
Decreased night vision
Problems with glare
Vision loss
References
Zigler JS Jr, Datiles MB III. Pathogenesis of cataracts. In: Tasman W, Jaeger EA, eds. Duane's Ophthalmology. 15th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2011: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.
Review Date: 9/16/2011
Reviewed By: 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.
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. Copyright 2004 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
Alternative Names
Lens opacity; Age-related cataract
Prevention
The best prevention involves controlling diseases that increase the risk of a cataract, and avoiding exposure to factors known to promote cataract formation.
Wearing sunglasses when you are outside during the day can reduce the amount of ultraviolet (UV) light your eyes are exposed to. Some sunglasses do not filter out the harmful UV. An optician should be able to tell you which sunglasses filter out the most UV. For patients who smoke cigarettes, quitting will decrease the risk of cataracts.
References
Zigler JS Jr, Datiles MB III. Pathogenesis of cataracts. In: Tasman W, Jaeger EA, eds. Duane's Ophthalmology. 15th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2011: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.
Review Date: 9/16/2011
Reviewed By: 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.
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. Copyright 2004 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
Review Date: 9/16/2011
Reviewed By: 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.
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. Copyright 2004 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.