Abnormal vs. normal
KC is when the structure and strength of the cornea is abnormal, and the cornea becomes cone shaped.
This causes IRREGULAR astigmatism
(think of a lop-sided football). The steeper axis is greater on one side of the center than the other. Astigmatism, even severe form, is when the cornea is shaped like the surface of a football, steeper in one axis than the other, the same on both sides of center.