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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 familiar sounds of your heart are made by the heart's valves as they open and close.
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Normal urine is sterile. It contains fluids, salts, and waste products. It is free of bacteria, viruses, and fungi.
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A seasonal flu vaccine is the best way to reduce the chances you will get seasonal influenza and spread it to others.