Anatomical changes of the cornea after laser in situ keratomileusis and their effects on it's refractive state

ABSTRACT

To study and evaluate anatomical changes of the cornea during wound healing process after laser in situ keratumelusis [LASIK] and their effects on the refractive state of the cornea. Retrospective noncomparative study. Fifty eyes of 30 subjects with myopic refractive error of-2 to -12 diopters [D] had LASIK and the LASIK was performed, confocal microscopy, optical coherence tomography, pachemetry, scanning slit topography, subjective, and objective refractometery were performed before, and 1.3,6 months after surgery. Changes in the corneal tissues, corned thickness, anterior, and posterior topography, and the amount of anterior shift of the posrerior corneal surface were compared with the amount of photoablation, and corneal refractivity, and it's stability. Multiple analysis was performed to asses the anatomical changes on corneal refractivity. Epithelial restoration of its preoperative thickness showed no significant correlation with refractive regression. Stromal regrowth correlates significantly with refractive changes, which increased proportionally with the actual phtoablation depth, with no significant correlation with haze, which correlates significantly with Increased numbers of anterior stromal wound healing keratocytes and keratocyte apoptosis. The amount of the photoablated stroma correlates significantly with the myopic regression, changes in the posterior corneal power, the amount of forward shift of the posterior corneal surface, and corneal thickness. Endothelial cell changes showed no significant effect on corneal refractivity. LASIK induces anatomical changes of the cornea, which lasts up to 6 months after surgery, the healing process period, that judges the refractive state of the cornea, and it's stability. Refractive state of the cornea, corneal thickness, anterior and posterior topography of the cornea are the main parameters that limit the amount of photoablation, which has a direct effect on the main outcome throught the whole period of corneal wound healing. Variables that were found to be relevant to refractive changes in the cornea after LASIK were preoperative refraction, corneal thickness, amount of laser ablation, amount of forward shift of the posterior corneal surface