The two images directly below are photographs of the cornea of a female patient who had RK and consequently developed ectasia. This cornea is only 180 microns thick at the thinnest point. Average corneal thickness for normal eyes is approximately 550 microns. As you can see, the corneal surface is very irregular, which causes distorted vision. Click on the images for a larger view. Below-left, the red arrow points to an old RK incision. Click image to enlarge. Below-right is a post-RK, post-LASIK cornea wearing a hard contact lens. Click image to enlarge.