Ok, just for fun, how would this be calculated?
I just read that with LASIK, for every diopter of myopia corrected, the cornea is thinned by 15 microns (0.0015 M).
Generally speaking, the cornea is about 550 microns thick, and as you know the central corneal anterior surface radius of curvature is about 43-46 diopters (although I'm not sure if that is a power approximation or the inverse of the radius of curvature in air*). Average corneal size is about 11.5-12 mm.
So, without the drudgery of doing the problem, what is the correct concept...difference in sagittal depth?
P.S. Just thought of this...sagitta...Sagittarius...the Archer..."Bow"!
*Ok, not to bog down, but keratometric measurements are not radii of curvature in air, but power estimations using the simple formula of F = (n'-n)/f. The cornea's refractive index is like water, i.e. 1.33, thus the true radius of curvature of the anterior cornea is more like 0.33/43 to 0.33/46, or 7.7 mm to 7.2.
Bookmarks