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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.
Asthma cases in Americans are about 75% higher today than they were in 1980.
Throughout history, plants containing cardiac steroids have been used as heart drugs and as poisons (e.g., in arrows used in combat), emetics, and diuretics.
The Romans did not use numerals to indicate fractions but instead used words to indicate parts of a whole.
Egg cells are about the size of a grain of sand. They are formed inside of a female's ovaries before she is even born.