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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.
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There are approximately 3 million unintended pregnancies in the United States each year.
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The longest a person has survived after a heart transplant is 24 years.
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The immune system needs 9.5 hours of sleep in total darkness to recharge completely.
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The word drug comes from the Dutch word droog (meaning "dry"). For centuries, most drugs came from dried plants, hence the name.