This diagram shows the curvature of the cornea, the outermost layer of the eyeball. When light hits the cornea, it bends to focus on the retina, the inner layer of the eye.
All corneas are individual and the center is steeper (more convex) that the periphery. This printout helps the doctors to most accurately fit contact lenses.
Both Lasik surgery and CRT Contact Lenses flatten the central steep portion of the cornea thereby eliminating myopia.