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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.
During the twentieth century, a variant of the metric system was used in Russia and France in which the base unit of mass was the tonne. Instead of kilograms, this system used millitonnes (mt).
Many people have small pouches in their colons that bulge outward through weak spots. Each pouch is called a diverticulum. About 10% of Americans older than age 40 years have diverticulosis, which, when the pouches become infected or inflamed, is called diverticulitis. The main cause of diverticular disease is a low-fiber diet.
Children of people with alcoholism are more inclined to drink alcohol or use hard drugs. In fact, they are 400 times more likely to use hard drugs than those who do not have a family history of alcohol addiction.
Vital signs (blood pressure, temperature, pulse rate, respiration rate) should be taken before any drug administration. Patients should be informed not to use tobacco or caffeine at least 30 minutes before their appointment.