Cataract (patient information)

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 * Assistant Editor(s)-In-Chief: Erin E. Lord

Overview
A cataract is a clouding of the lens in the eye that affects vision. It can occur in either or both eyes, but it cannot spread from one eye to the other.

What are the symptoms of a cataract?
Visual problems may include the following changes:


 * Cloudy, blurry, fuzzy, foggy, or filmy vision
 * Loss of color intensity
 * Double vision or multiple images in one eye
 * Difficulty seeing at night
 * Problems seeing shapes against a background or the difference between shades of colors
 * Seeing halos around lights
 * Being sensitive to glare

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

What are the causes of a cataract?
In many cases, the cause of cataract development is unknown. Adult cataracts usually develop very gradually with advancing age and may run in families. They develop slowly and painlessly, and vision in the affected eye or eyes slowly gets worse. Some researchers suspect that a cataract may form as the protein in the lens changes from the wear and tear it takes over the years.

Although most cataracts are related to aging, there are other types and causes of cataract:


 * Secondary cataract: Cataracts can form after surgery for other eye problems, such as glaucoma. Cataracts also can develop in people who have other health problems, such as diabetes. Cataracts are sometimes linked to use of corticosteroids and certain other medications, such as cortisone.
 * Traumatic cataract: Cataracts can develop after an eye injury, sometimes years later.
 * Congenital cataract Some babies are born with cataracts or develop them in childhood, often in both eyes. These cataracts may be so small that they do not affect vision. If they do, the lenses may need to be removed.
 * Radiation cataract: Cataracts can develop after exposure to some types of radiation.

Cataracts develop more quickly if there are some environmental factors, such as smoking, exposure to other toxic substances, and exposure to excessive ultraviolet light or sunlight.

Who is at highest risk?
The risk of cataract increases as you get older. Other risk factors for cataract include:


 * Certain diseases such as diabetes.
 * Personal behavior such as smoking and alcohol use.
 * The environment such as prolonged exposure to UV light and sunlight.

How to know you have a cataract?
A standard eye exam and slit lamp examination are used to diagnose cataracts. Other diagnostic tests are rarely needed.

A comprehensive eye exam includes:
 * Visual acuity test: This eye chart test measures how well you see at various distances.
 * Dilated eye exam: Drops are placed in your eyes to widen, or dilate, the pupils. Your eye care professional uses a special magnifying lens to examine your retina and optic nerve for signs of damage and other eye problems. After the exam, your close-up vision may remain blurred for several hours.
 * Tonometry: An instrument measures the pressure inside the eye. Numbing drops may be applied to your eye for this test.

When to seek urgent medical care
Call for an appointment with a health care provider in the event of vision loss, decreased night vision, or problems with glare.

Treatment options
The symptoms of early cataract may be improved with new eyeglasses, brighter lighting, anti-glare sunglasses, or magnifying lenses. If these measures do not help, surgery is the only effective treatment. Surgery involves removing the cloudy lens and replacing it with an artificial lens.

If a cataract is not bothersome, then surgery is usually not necessary. However, some people may have additional eye problems, such as diabetic retinopathy, that cannot be treated without first having cataract surgery.

For some people, changing glasses, getting stronger bifocals, or using a magnifying lens is helpful enough. A cataract needs to be removed only when vision loss interferes with your everyday activities, such as driving, reading, or watching TV.

For more information on the different types of surgeries, see: Cataract surgery.

Diseases with similar symptoms
Several diseases may have symptoms similar to cataracts, including:


 * Age-related macular degeneration
 * Glaucoma
 * Ocular histoplasmosis syndrome
 * Corneal dystrophy
 * Diabetes

Where to find medical care for a cataract
Directions to Hospitals Treating a cataract

Prevention of a cataract
Wearing sunglasses and a hat with a brim to block ultraviolet sunlight may help to delay cataract. If you smoke, stop. Researchers also believe good nutrition can help reduce the risk of age-related cataract. They recommend eating green leafy vegetables, fruit, and other foods with antioxidants.

If you are age 60 or older, you should have a comprehensive dilated eye exam at least once every two years. In addition to cataract, your eye care professional can check for signs of age-related macular degeneration, glaucoma, and other vision disorders. Early treatment for many eye diseases may save your sight.

What to expect (Outlook/Prognosis)?
Vision may not improve to 20/20 after cataract surgery if other eye diseases, such as macular degeneration, are present. Eye doctors can usually, but not always, determine this in advance.

Additional links
http://www.nei.nih.gov/health/cataract/cataract_facts.asp http://www.nlm.nih.gov/medlineplus/ency/article/001001.htm