Astigmatism causes blurred vision due either to the irregular shape of the cornea, the clear front cover of the eye, or sometimes the curvature of the lens inside the eye. An irregular shaped cornea or lens prevents light from focusing properly on the retina, the light sensitive surface at the back of the eye. As a result, vision becomes blurred at any distance.
Astigmatism is a refractive error of the eye where there is a difference in the focussing power of the eye in different meridians.
In a very simple sense the curvature of the cornea can be described as the curvature of a rugby ball which is varied over the surface instead of having a constant radius like the curve of a football (which is a sphere).
Usually astigmatism is hereditary. Some people are born with an oblong cornea, and the resulting vision problem may get worse over time. Astigmatism may also be the result of an eye injury that has caused scarring on the cornea or from certain types of eye surgery or from keratoconus a disease that causes a gradual thinning of the cornea.
The result of astigmatism is that objects can appear distorted or blurry at distance and near. The laser is used to reshape the corneal surface and create a more smooth corneal profile. This reduces the irregularity in curvature and restores vision. Astigmatic correction is incorporated in the laser treatment plan for all patients who require it, to give the best possible outcome for vision.