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Astigmatism is the most common vision problem. It may accompany nearsightedness or farsightedness. It is usually caused by an irregularly shaped cornea, but sometimes it is the result of an irregularly shaped lens. Either type can be corrected by eyeglasses, contact lenses, or refractive surgery.
Barbituric acid, the base material of barbiturates, was first synthesized in 1863 by Adolph von Bayer. His company later went on to synthesize aspirin for the first time, and Bayer aspirin is still a popular brand today.
Blood in the urine can be a sign of a kidney stone, glomerulonephritis, or other kidney problems.
On average, someone in the United States has a stroke about every 40 seconds. This is about 795,000 people per year.
There are over 65,000 known species of protozoa. About 10,000 species are parasitic.