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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.
There are over 65,000 known species of protozoa. About 10,000 species are parasitic.
There are approximately 3 million unintended pregnancies in the United States each year.
It is believed that humans initially contracted crabs from gorillas about 3 million years ago from either sleeping in gorilla nests or eating the apes.
According to the FDA, adverse drug events harmed or killed approximately 1,200,000 people in the United States in the year 2015.