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Alternative namesLens opacity
DefinitionA cataract is a cloudy or opaque area in the lens of the eye.
Causes, incidence, and risk factors
The lens of an eye is normally clear. If the lens becomes cloudy, the condition is known as a cataract. Rarely, cataracts may be present at or shortly after birth. These are called congenital cataracts .
Adult cataracts usually develop with advancing age and may run in families. Cataracts are accelerated by environmental factors, such as smoking or exposure to other toxic substances, or they may develop at any time after an eye injury. Metabolic diseases such as diabetes also greatly increase the risk for cataracts. Certain medications, such as cortisone, can also accelerate cataract formation.
Congenital cataracts can also be caused by infections of the mother during pregnancy such as rubella , or associated with metabolic disorders such as galactosemia . Risk factors include inherited metabolic diseases, a family history of cataracts, and maternal viral infection.
Visual problems may include the following changes:
Vision problems associated with cataracts generally progress to decreased visual acuity, even in daylight.
Factors that may contribute to cataract development are low serum calcium levels, diabetes, long-term use of corticosteroids, and various inflammatory and metabolic disorders. Environmental causes include trauma, radiation exposure, and excessive exposure to ultraviolet light (sunlight).
In many cases, the cause of cataract is unknown.
Signs and tests
Other tests that may be done (rarely) include:
The only treatment for cataract is surgical removal. This is done when a person cannot see well enough with glasses to perform normal activities. For some people, changing glasses, getting stronger bifocals, or using a magnifying lens is helpful enough. Others choose to have cataract surgery .
There are 2 types of surgery that can be used to remove lenses that have a cataract.
Extracapsular surgery consists of surgically removing the lens, but leaving the back half of the capsule (the outer covering of the lens) intact. High-frequency sound waves (phacoemulsification) may be used to soften the lens to facilitate removal through a smaller incision.
People who have cataract surgery are usually fitted with an artificial lens at the same time. The artificial lens is a synthetic disc called an intraocular lens. It is usually placed in the lens capsule inside the eye.
Expectations (prognosis)For most people, cataract surgery has a low risk of complications. With implanted artificial lenses, most people no longer need corrective lenses for distance vision. Glasses are usually necessary for reading.
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.
In infants, amblyopia and decreased visual development may occur as a result of cataracts. Early diagnosis and treatment is essential.
Calling your health care provider
Call for an appointment with your health care provider if you have symptoms such as progressive deterioration of vision, decreased night vision, or problems with glare.
Also call if you have a family history of congenital cataracts or if your child has symptoms or signs suggestive of a cataract.
The primary prevention involves controlling associated diseases and avoiding exposure to factors known to promote cataract formation.
Update Date: 11/1/2002Dave Lee, M.D., Department of Ophthalmology, Saint Louis University Eye Institute, St. Louis, MO. Review provided by VeriMed Healthcare Network.
Last updated: Tue, 06 Jan 2009 00:20:03 GMT