Astigmatism is caused by an abnormal shape of the cornea which, instead of being spherical, is slightly oblong, like a football. This vision problem makes it difficult to see clearly in the distance and at close range. Many people have astigmatism combined with myopia or hyperopia, but astigmatism may also be the only refractive error.
The surgery allows us to reshape their cornea and make it spherical. Astigmatism can be regular or irregular. However, irregular astigmatism cannot be corrected with standard lasik.