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Did you know?
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.
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Most childhood vaccines are 90–99% effective in preventing disease. Side effects are rarely serious.
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The average adult has about 21 square feet of skin.
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Urine turns bright yellow if larger than normal amounts of certain substances are consumed; one of these substances is asparagus.
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About 600,000 particles of skin are shed every hour by each human. If you live to age 70 years, you have shed 105 pounds of dead skin.