Normally, the front surface of the eye (the cornea) is shaped like a sphere (basketball). This permits light to focus in one distinct point, which is necessary for clear vision. When the cornea is oval, or shaped like a football, a condition known as astigmatism is present. Astigmatism causes light to focus in more than one point, resulting in blurred vision.

Astigmatism is corrected with glasses or contact lenses, but can be permanently corrected surgically. Corneal relaxing incisions placed on the steep axis of the cornea can reduce or eliminate astigmatism, thereby reducing the eye´s dependency upon glasses or contact lenses.