I am pleased to see the proposed additional guideline by Thomas Kohnen, MD. I have a member in the Ectasia Support/Study Group who could have been spared from this complication if this guideline had been followed and this member had been offered PRK instead of LASIK.
The pre-op central pachymetry was 491 OD and 471 OS. Pre-op manifest refraction -2.50 +2.00 x 115 OD ; -3.50 +2.00 x 68 OS This member developed ectasia OS despite a low correction and normal pre-op topographies.

Journal of Cataract & Refractive Surgery
December 2002

From the editor
Iatrogenic keratectasia: Current knowledge, current measurements
Thomas Kohnen, MD
http://www.ascrs.org/publications/jcrs/1202_edit.html
"I would like to propose an additional guideline that I now follow in my practice: Do not perform LASIK in patients with corneas less than 500 μm at the thinnest point. I base this on 1 published case (both eyes)4 and verbal reports of ectasia occurring after LASIK in these corneas."