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A cataract is a clouding of the eyes' natural lens. As we age, some clouding of the lens may occur. The first sign of a cataract is usually blurry vision. Although glasses and other visual aids may at first help a person with cataracts, surgery may become inevitable. Cataract surgery is very successful in restoring vision, and it is the most frequently performed surgery in the United States.
Thyroid conditions cause a higher risk of fibromyalgia and chronic fatigue syndrome.
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.
There are 20 feet of blood vessels in each square inch of human skin.
More than 2,500 barbiturates have been synthesized. At the height of their popularity, about 50 were marketed for human use.