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Did you know?
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.
Did you know?
More than 2,500 barbiturates have been synthesized. At the height of their popularity, about 50 were marketed for human use.
Did you know?
There are 20 feet of blood vessels in each square inch of human skin.
Did you know?
Many of the drugs used by neuroscientists are derived from toxic plants and venomous animals (such as snakes, spiders, snails, and puffer fish).
Did you know?
People about to have surgery must tell their health care providers about all supplements they take.