What is Astigmatism?

Astigmatism is the condition when the focal system of the eye (cornea and lens) fail to focus all light rays to a point.  There are two focal points one from the steep meridian and one from the flat meridian.  Astigmatism is not a disease, per se, but it does lead to blurred vision.  The best way to understand astigmatism is to visualize the eye shaped like a football rather than a baseball.  The football has two curves along the short and long axes.

astigmatism_imageAstigmatism results in vision is blurred at all distances. This condition is the result of having a corneal surface that is irregular in shape, somewhat like a football instead of a more round like a baseball or basketball. With astigmatism, the rays of light do not converge or focus into a single point but form two or more focal points. Thus the eye is unable to focus clearly at any distance because of this irregular focusing surface. This causes people to experience blurry or distorted vision.  If there are two principal focal planes 90 degrees apart, this is considered regular astigmatism.  If the surface of the cornea is very irregular like the surface of a raisin, this results in multiple points and poor vision that is not correctable with glasses and must be corrected with a rigid contact lens or by smoothing out the surface with surgery.