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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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The first documented use of surgical anesthesia in the United States was in Connecticut in 1844.
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Multiple experimental evidences have confirmed that at the molecular level, cancer is caused by lesions in cellular DNA.
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Long-term mental and physical effects from substance abuse include: paranoia, psychosis, immune deficiencies, and organ damage.
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Asthma cases in Americans are about 75% higher today than they were in 1980.