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Cataract
Definition:
A cataract is a cloudy or opaque area in the lens of the eye. Alternative Names:
Lens opacity
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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 may be inherited. The gene for such cataracts is dominant (autosomal dominant inheritance), which means that the defective gene will cause the condition even if only one parent passes it along. Approximately 50% of children in such families will be affected. 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.
Adult cataracts are generally associated with aging. They develop slowly and painlessly with a gradual onset of difficulty with vision. Visual problems may include the following changes: - Difficulty seeing at night
- Seeing halos around lights
- Being sensitive to glare
Vision problems associated with cataracts generally progress to decreased visual acuity, even in daylight.
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