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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.
When blood is exposed to air, it clots. Heparin allows the blood to come in direct contact with air without clotting.
After a vasectomy, it takes about 12 ejaculations to clear out sperm that were already beyond the blocked area.
More than 34,000 trademarked medication names and more than 10,000 generic medication names are in use in the United States.
There are over 65,000 known species of protozoa. About 10,000 species are parasitic.