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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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Nearly 31 million adults in America have a total cholesterol level that is more than 240 mg per dL.
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There are over 65,000 known species of protozoa. About 10,000 species are parasitic.
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People about to have surgery must tell their health care providers about all supplements they take.
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Bacteria have flourished on the earth for over three billion years. They were the first life forms on the planet.