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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.
Cytomegalovirus affects nearly the same amount of newborns every year as Down syndrome.
Vaccines prevent between 2.5 and 4 million deaths every year.
The modern decimal position system was the invention of the Hindus (around 800 AD), involving the placing of numerals to indicate their value (units, tens, hundreds, and so on).
Malaria was not eliminated in the United States until 1951. The term eliminated means that no new cases arise in a country for 3 years.