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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.
The human body produces and destroys 15 million blood cells every second.
More than 2,500 barbiturates have been synthesized. At the height of their popularity, about 50 were marketed for human use.
All adults should have their cholesterol levels checked once every 5 years. During 2009–2010, 69.4% of Americans age 20 and older reported having their cholesterol checked within the last five years.
In 1864, the first barbiturate (barbituric acid) was synthesized.