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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The ratio of hydrogen atoms to oxygen in water (H2O) is 2:1.
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There are more bacteria in your mouth than there are people in the world.
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In the United States, there is a birth every 8 seconds, according to the U.S. Census Bureau's Population Clock.
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Limit intake of red meat and dairy products made with whole milk. Choose skim milk, low-fat or fat-free dairy products. Limit fried food. Use healthy oils when cooking.
The Three Stages of the Birth Process
Color mixtures of refracted light—additive process.