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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.
Vampire bats have a natural anticoagulant in their saliva that permits continuous bleeding after they painlessly open a wound with their incisors. This capillary blood does not cause any significant blood loss to their victims.
Oliver Wendell Holmes is credited with introducing the words "anesthesia" and "anesthetic" into the English language in 1846.
One way to reduce acid reflux is to lose two or three pounds. Most people lose weight in the belly area first when they increase exercise, meaning that heartburn can be reduced quickly by this method.
More than 2,500 barbiturates have been synthesized. At the height of their popularity, about 50 were marketed for human use.