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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.
No drugs are available to relieve parathyroid disease. Parathyroid disease is caused by a parathyroid tumor, and it needs to be removed by surgery.
The eye muscles are the most active muscles in the whole body. The external muscles that move the eyes are the strongest muscles in the human body for the job they have to do. They are 100 times more powerful than they need to be.
Sperm cells are so tiny that 400 to 500 million (400,000,000–500,000,000) of them fit onto 1 tsp.
Alzheimer's disease affects only about 10% of people older than 65 years of age. Most forms of decreased mental function and dementia are caused by disuse (letting the mind get lazy).