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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?
The human body produces and destroys 15 million blood cells every second.
Did you know?
There are 20 feet of blood vessels in each square inch of human skin.
Did you know?
The first oral chemotherapy drug for colon cancer was approved by FDA in 2001.
Did you know?
There are over 65,000 known species of protozoa. About 10,000 species are parasitic.