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People who have myopia, or nearsightedness, are not able to see objects at a distance but only up close. It occurs when the cornea is either curved too steeply, the eye is too long, or both. This condition is progressive and worsens with time. More than 100 million people in the United States are nearsighted, but only 20% of those are born with the condition. Diet, eye exercise, drug therapy, and corrective lenses can all help manage nearsightedness.
The toxic levels for lithium carbonate are close to the therapeutic levels. Signs of toxicity include fine hand tremor, polyuria, mild thirst, nausea, general discomfort, diarrhea, vomiting, drowsiness, muscular weakness, lack of coordination, ataxia, giddiness, tinnitus, and blurred vision.
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).
The use of salicylates dates back 2,500 years to Hippocrates's recommendation of willow bark (from which a salicylate is derived) as an aid to the pains of childbirth. However, overdosage of salicylates can harm body fluids, electrolytes, the CNS, the GI tract, the ears, the lungs, the blood, the liver, and the kidneys and cause coma or death.