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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?
There are 60,000 miles of blood vessels in every adult human.
Did you know?
There are approximately 3 million unintended pregnancies in the United States each year.
Did you know?
The immune system needs 9.5 hours of sleep in total darkness to recharge completely.
Did you know?
The calories found in one piece of cherry cheesecake could light a 60-watt light bulb for 1.5 hours.