What is Astigmatism?

Astigmatism is the most commonly occuring refractive error, but many don't know what astigmatism means or how the eye works. Astigmatism occurs when one of the parts of the eye, the cornea, is not perfectly spherical. Instead of being spherical like a basketball, it is round and distorted, like a football. The result is blurry or distorted vision at all distances because of the irregular corneal surface. This should not be confused with having double vision.

There are two "types" of astigmatism, regular and irregular. Regular astigmatism is typically easy to correct, however — due to the possible complexities involved — irregular astigmatism can prove more challenging.

Astigmatism is usually hereditary, but can be caused by eye injuries from surgeries and the eye disease keratoconus, where the cornea thins and bulges, transforming into a cone-like shape.

Astigmatism does not cause eye pain and it is not an eye infection. Through proper eye care and visiting your eye doctor, you can correct vision impairments caused by astigmatism.

The following websites provide descriptions of astigmatism, including how to tell if you have astigmatism, and graphics to help you understand astigmatism:

For more information, read about how astigmatism can be corrected.