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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.
Cyanide works by making the human body unable to use oxygen.
Cancer has been around as long as humankind, but only in the second half of the twentieth century did the number of cancer cases explode.
People with high total cholesterol have about two times the risk for heart disease as people with ideal levels.
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.