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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.
Human neurons are so small that they require a microscope in order to be seen. However, some neurons can be up to 3 feet long, such as those that extend from the spinal cord to the toes.
There are approximately 3 million unintended pregnancies in the United States each year.
Medication errors are more common among seriously ill patients than with those with minor conditions.
More than 4.4billion prescriptions were dispensed within the United States in 2016.