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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.
Approximately 70% of expectant mothers report experiencing some symptoms of morning sickness during the first trimester of pregnancy.
There are over 65,000 known species of protozoa. About 10,000 species are parasitic.
Intradermal injections are somewhat difficult to correctly administer because the skin layers are so thin that it is easy to accidentally punch through to the deeper subcutaneous layer.
The human body produces and destroys 15 million blood cells every second.