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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.
The first-known contraceptive was crocodile dung, used in Egypt in 2000 BC. Condoms were also reportedly used, made of animal bladders or intestines.
More than 30% of American adults, and about 12% of children utilize health care approaches that were developed outside of conventional medicine.
There are over 65,000 known species of protozoa. About 10,000 species are parasitic.
Multiple experimental evidences have confirmed that at the molecular level, cancer is caused by lesions in cellular DNA.