What is Astigmatism ?

Astigmatismis an optical defect in which vision is blurred due to the inability of the optics of the eye to focus a point object into a sharp focused image on the retina. This may be due to an irregular or toric curvature of thecorneaorlens. The two types of astigmatism are regular and irregular.Irregular astigmatismis often caused by a corneal scar or scattering in the crystalline lens, and cannot be corrected by standard spectacle lenses, but can be corrected by contact lenses. The more commonregular astigmatismarising from either the cornea or crystalline lens can be corrected byeyeglassesortoric lenses. A 'toric' surface resembles a section of the surface of aRugby ballor adoughnutwhere there are two regular radii, one smaller than the other one. This optical shape gives rise to astigmatism in the eye.