What is astigmatism?

To illustrate what this disorder really is, compare a football to a basketball. The football has a lot of astigmatism because it is not perfectly round, whereas the basketball has none.

Similarly, two round surfaces in the eye are responsible for focusing light: the cornea and the lens, which resides just behind the colored part of the eye (the iris). If one or both of these surfaces are not perfectly spherical or round, this will cause astigmatism.

The usual site of this irregularity in the eye is the cornea. It is a normal variant and, if present, may be considered one of nature's imperfections.

Astigmatism can cause blurred vision and eye strain. Small amounts may be ignored, but if symptoms are present, they can be corrected by glasses or contact lenses. In most patients hard contact lenses do a better job of correcting these symptoms than soft contact lenses, although soft "toric" contact lenses can correct small amounts of the disorder and still provide good vision.