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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.
After 5 years of being diagnosed with rheumatoid arthritis, one every three patients will no longer be able to work.
All patients with hyperparathyroidism will develop osteoporosis. The parathyroid glands maintain blood calcium within the normal range. All patients with this disease will continue to lose calcium from their bones every day, and there is no way to prevent the development of osteoporosis as a result.
When blood is exposed to air, it clots. Heparin allows the blood to come in direct contact with air without clotting.
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).