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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.
Amphetamine poisoning can cause intravascular coagulation, circulatory collapse, rhabdomyolysis, ischemic colitis, acute psychosis, hyperthermia, respiratory distress syndrome, and pericarditis.
The horizontal fraction bar was introduced by the Arabs.
Nitroglycerin is used to alleviate various heart-related conditions, and it is also the chief component of dynamite (but mixed in a solid clay base to stabilize it).
On average, someone in the United States has a stroke about every 40 seconds. This is about 795,000 people per year.