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A cataract is a clouding of the eyes' natural lens. As we age, some clouding of the lens may occur. The first sign of a cataract is usually blurry vision. Although glasses and other visual aids may at first help a person with cataracts, surgery may become inevitable. Cataract surgery is very successful in restoring vision, and it is the most frequently performed surgery in the United States.
Cancer has been around as long as humankind, but only in the second half of the twentieth century did the number of cancer cases explode.
People with high total cholesterol have about two times the risk for heart disease as people with ideal levels.
There are over 65,000 known species of protozoa. About 10,000 species are parasitic.
Prostaglandins were first isolated from human semen in Sweden in the 1930s. They were so named because the researcher thought that they came from the prostate gland. In fact, prostaglandins exist and are synthesized in almost every cell of the body.