cat·a·ract / ˈkatəˌrakt/ • n. 1. a large waterfall. ∎  a sudden rush of water; a downpour: the rain enveloped us in a deafening cataract.2. (usu. cataracts) a medical condition in which the lens of the eye becomes progressively opaque, resulting in blurred vision.

CATARACT

Cataract, the leading cause of blindness worldwide, is a clouding of the crystalline lens of the eye. Symptoms of cataract include blurred vision, difficulty reading print and street signs, light sensitivity, and glare disability. Most cataracts are agerelated, but environmental factors such as ultraviolet light exposure, tobacco smoking, diabetes mellitus, trauma, certain congenital infections, and some medications can accelerate their growth. In some hereditary conditions, such as galactosemia, a single gene defect is responsible. Treatment of visually significant cataract, which is highly successful, involves surgically removing the cloudy lens and implanting a clear plastic replacement lens.

Kevin M. Miller

(see also: Vision Disorders )

cataract (kat-ă-rakt) n. any opacity in the lens of the eye, resulting in blurred vision. Cataracts most commonly occur in the elderly (senile c.), but some are congenital or result from metabolic disease (such as diabetes) or from injury to the lens or exposure of the eye to harmful radiation.

cataract †(pl.) floodgates of heaven (cf. Gen. 7: 11, 8: 2) XV; †waterspouts; (sg.) waterfall; opacity of the lens of the eye (prob. fig. use of the sense ‘portcullis’) XVI. — L. cataracta — Gr. katar(r)hāktḗs down-rush, waterfall, portcullis.

cataract Opacity in the lens of an eye, causing blurring of vision. Most cases are due to degenerative changes in old age but it can also be congenital, the result of damage to the lens, or some metabolic disorder such as diabetes. Treatment is by removal of the cataract and implanting an artificial lens.