Astigmatic keratotomy (AK)
How astigmatic keratotomy (AK) works
The cornea is the eye's outer clear window which partially focuses the light that enters the eye. Astigmatism is caused by a cornea which is asymmetric; it is steeper in one direction and flatter in the other direction, like a football. By reshaping the cornea to make it more symmetrical, like a basketball, the surgeon can reduce or eliminate astigmatism.