Astigmatism Astigmatism Definition Symptoms Treatment Clinic Information Definition Astigmatism is one of a group of eye conditions known as refractive errors .
Refractive errors cause a disturbance in the way that light rays are focused within the eye.
Astigmatism often occurs with nearsightedness and farsightedness , conditions also resulting from refractive errors. It simply means that you have a variation or disturbance in the shape of your cornea. Astigmatism usually occurs when the front surface of the eye, the cornea, has an irregular curvature. Normally the cornea is smooth and equally curved in all directions and light entering the cornea is focused equally on all planes, or in all directions. In astigmatism, the front surface of the cornea is curved more in one direction than in the other.