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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 heart is located in the center of the chest, with part of it tipped slightly so that it taps against the left side of the chest.
The modern decimal position system was the invention of the Hindus (around 800 AD), involving the placing of numerals to indicate their value (units, tens, hundreds, and so on).
Thyroid conditions may make getting pregnant impossible.
Between 1999 and 2012, American adults with high total cholesterol decreased from 18.3% to 12.9%