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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.
The word drug comes from the Dutch word droog (meaning "dry"). For centuries, most drugs came from dried plants, hence the name.
The Babylonians wrote numbers in a system that used 60 as the base value rather than the number 10. They did not have a symbol for "zero."
Today, nearly 8 out of 10 pregnant women living with HIV (about 1.1 million), receive antiretrovirals.
The eye muscles are the most active muscles in the whole body. The external muscles that move the eyes are the strongest muscles in the human body for the job they have to do. They are 100 times more powerful than they need to be.