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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.
After 5 years of being diagnosed with rheumatoid arthritis, one every three patients will no longer be able to work.
More than 20 million Americans cite use of marijuana within the past 30 days, according to the National Survey on Drug Use and Health (NSDUH). More than 8 million admit to using it almost every day.
There are over 65,000 known species of protozoa. About 10,000 species are parasitic.
Warfarin was developed as a consequence of the study of a strange bleeding disorder that suddenly occurred in cattle on the northern prairies of the United States in the early 1900s.