We need to change our technique for measuring that. We need to be looking at contrast sensitivity, glare, and standardizing measurements for these abnormalities. Customized ablations will improve these measurements. We were surprised to see that almost all the myopes had coma induced toward the hinge and almost all the hyperopes had coma induced away from the hinge. Although you could come up with average values, you couldn t predict for each individual patient and fudge it into the formula.
Hydration makes so much difference, microstriae make so much difference.
Whether the stromal bed is a little edematous when the flap goes down and you have a wider gutter, or whether it fits snugly, all has an effect. PRK is not economical on the laser chain. If the IntraLase femtosecond laser is as good as it sounds, you will be able to cut in an exact place with an exact dimension. That would be highly desirable in eliminating some uncertainties, in terms of the anatomical customization. I think a good portion of the aberrations are not necessarily from the way the flap is cut or the bed s irregularities, but the way that you lay the flap down.