By Judith Lee and Gretchyn Bailey; reviewed by Vance Thompson, MD; Flash illustration by Stephen Bagi

"What is a stigmatism?" is a question that eye doctors hear every day, but actually it's spelled "astigmatism." Although astigmatism is the most common vision problem, most people don't know what it is.

Astigmatism may accompany farsightedness or nearsightedness. Usually it is caused by an irregularly shaped cornea (called corneal astigmatism). But sometimes lenticular astigmatism results from an irregularly shaped lens, which is located behind the cornea. Either kind of astigmatism can usually be corrected with eyeglasses, contact lenses, or refractive surgery.