Abstract
Abstract: :
Understanding how optical aberrations vary after LASIK surgery is fundamental to the future development of aberration-free guided ablations. Previous research has shown that LASIK induces higher order optical aberrations in the human eye. Custom ablations which target higher order aberrations are now possible. If the amount of generated aberration from LASIK surgery could be shown to decrease with subsequent treatments to the same eye, then the potential might exist to neutralize or at least minimize the induced aberrations by performing enhancement surgery. Purpose: To compare the induced total higher order aberrations from primary LASIK surgery with that from LASIK enhancement surgery to the same eye. Methods: Wavefront analysis using a Hartmann-Shack aberrometer (Complete Ophthalmic Analysis System, Wavefront Sciences, Albuquerque, NM) was performed on 19 consecutive eyes undergoing LASIK enhancement over a 10 month period for under-treatment of either simple myopia or myopia with astigmatism. The surgical parameters were controlled across treatments. The difference in total higher order wavefront aberration preoperatively and one-month post-operatively was compared between the initial and enhancement procedures, using the paired student t-test. Results: Both the initial and enhancement procedures were found to generate increases in the value of total higher order aberrations (RMS (root mean square) pre-LASIK 0.084+/-0.040 to post-LASIK 0.12+/-0.052 [P=0.02]; RMS pre-enhancement 0.12+/-0.038 to post-enhancement 0.16 +/- 0.080 [P=0.06] ). The amount of higher order aberration generated by LASIK was statistically equal between the initial and enhancement procedures (0.038 +/- 0.046 and 0.039 +/- 0.075 [P=0.04]). Conclusions: Our results suggest that subsequent LASIK treatment generates as much higher order optical aberration as initial treatment in a myopic eye. Therefore, the limiting step in achieving aberration-free vision may involve factors beyond the technical limit of identifying and treating higher order aberrations. Such factors could include corneal healing and varying corneal surface characteristics over time, for example.
Keywords: refractive surgery • refractive surgery: other technologies