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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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.
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In most cases, kidneys can recover from almost complete loss of function, such as in acute kidney (renal) failure.
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It is widely believed that giving a daily oral dose of aspirin to heart attack patients improves their chances of survival because the aspirin blocks the formation of new blood clots.
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Most childhood vaccines are 90–99% effective in preventing disease. Side effects are rarely serious.
