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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.
The U.S. Preventive Services Task Force recommends that all women age 65 years of age or older should be screened with bone densitometry.
Chronic marijuana use can damage the white blood cells and reduce the immune system's ability to respond to disease by as much as 40%. Without a strong immune system, the body is vulnerable to all kinds of degenerative and infectious diseases.
The human body produces and destroys 15 million blood cells every second.
Fewer than 10% of babies are born on their exact due dates, 50% are born within 1 week of the due date, and 90% are born within 2 weeks of the date.