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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.
Did you know?
In 1864, the first barbiturate (barbituric acid) was synthesized.
Did you know?
It is difficult to obtain enough calcium without consuming milk or other dairy foods.
Did you know?
Alzheimer's disease affects only about 10% of people older than 65 years of age. Most forms of decreased mental function and dementia are caused by disuse (letting the mind get lazy).
Did you know?
Bacteria have flourished on the earth for over three billion years. They were the first life forms on the planet.