Astigmatism is a condition where the front of the cornea is not equally curved, it is slightly oval in shape. As a result, the rays of light that enter the eye are bent unequally and cause distortion of the image.
Most people have some degree of astigmatism.
The oval shape of the cornea can be reshaped by the Excimer Laser so that the cornea is equally round and vision is greatly improved. Presbyopia is not affected by the laser treatment.