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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.
Bacteria have flourished on the earth for over three billion years. They were the first life forms on the planet.
In 1844, Charles Goodyear obtained the first patent for a rubber condom.
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.
Calcitonin is a naturally occurring hormone. In women who are at least 5 years beyond menopause, it slows bone loss and increases spinal bone density.