Purpose: The aim of this study was to evaluate the possible topographic epithelial profile thickness changes (remodeling) after high myopic femtosecond laser in situ keratomileusis (LASIK) with concurrent prophylactic high-fluence cross-linking (CXL) in comparison with standard femtosecond LASIK.
Methods: Preoperative and 6-month postoperative 3-dimensional epithelial thickness distribution maps were investigated through clinical spectral domain anterior-segment optical coherence tomography in 2 groups of femtosecond laser-assisted myopic LASIK cases. Group A represented 67 eyes treated additionally with concurrent prophylactic CXL (LASIK-Xtra); group B represented 72 eyes subjected to stand-alone femtosecond LASIK. Optical coherence tomography measurements of the epithelial thickness over the center 2-mm-diameter disk, mid-peripheral 5-mm rim, and overall (the entire 6-mm-diameter disc area) were investigated.
Results: The comparison of matched myopic correction subgroups indicated statistically significant differences in the epithelial thickness increase specifically between high myopia subgroups. For example, in group A (LASIK-Xtra), the mid-peripheral epithelial thickness increase was +3.79 and +3.95 μm for the "-8.00 to -9.00 diopter" and "-7.00 to -8.00 diopter" subgroups, which compare with increased thickness in group B (stand-alone LASIK), of +9.75 μm (P = 0.032) and +7.14 μm (P = 0.041), respectively, for the same subgroups.
Conclusions: Application of prophylactic CXL concurrently with high myopic LASIK operation results in a statistically significant reduced epithelial increase in comparison with stand-alone LASIK. This comparison is observed between matched high myopic correction subgroups. This difference may correlate with higher regression rates and/or may depict increased biomechanical instability in stand-alone LASIK.