|
|
Did you know?
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.
Did you know?
The horizontal fraction bar was introduced by the Arabs.
Did you know?
Calcitonin is a naturally occurring hormone. In women who are at least 5 years beyond menopause, it slows bone loss and increases spinal bone density.
Did you know?
Excessive alcohol use costs the country approximately $235 billion every year.
Did you know?
Approximately 500,000 babies are born each year in the United States to teenage mothers.