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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?
Everyone has one nostril that is larger than the other.
Did you know?
Vaccines cause herd immunity. If the majority of people in a community have been vaccinated against a disease, an unvaccinated person is less likely to get the disease since others are less likely to become sick from it and spread the disease.
Did you know?
Vaccines prevent between 2.5 and 4 million deaths every year.
Did you know?
On average, the stomach produces 2 L of hydrochloric acid per day.