Abstract
Purpose: :
To assess and compare corneal modifications induced by IntraLase PulsionFS® femtosecond laser and mechanical microkeratome Hansatome® for LASIK using the new–generation Heidelberg Retina Tomograph II (HRT–II)/ Rostock Cornea Module confocal microscope.
Methods: :
In this case–control study, 26 eyes of 13 patients were examined with the HRT–II in the follow–up of IntraLase® femtosecond laser for LASIK myopic surgery. 22 eyes of 11 patients were also examined after microkeratome Hansatome®–LASIK surgery. In both groups, the first examination was performed on day 7 and the last on month 12 after surgery. Morphological modifications of corneal architecture were evaluated and comparisons were made between the two flap–formation techniques.
Results: :
Evaluation of both groups on day 7 showed keratocyte transformation, most likely related to cellular activation beneath the interface. The flap margin after the IntraLase® technique appeared microscopically as a very clear–cut edge that included epithelial plug. We also observed some brightly reflecting particles together with scattered less bright dots, from day 7 until 1 year. At month 2, secondary fibrosis, adjacent to the still well–defined IntraLase® flap edge, was observed. At months 6 and 12, this reaction diminished with time, leaving a fibrotic scar adjacent to a wound constriction with expulsion of the epithelial plug of more or less importance depending upon the initial separation of the margins. The flap margin of the mechanical microkeratome had the appearance of a less clearly identified fibrotic scar with no epithelial plug.
Conclusions: :
This study reveals morphological similarities between the interfaces obtained by femtosecond laser and mechanical microkeratome, likely because the same excimer laser performed the photoablation. However, the IntraLase® flap margin showed greater fibrotic scarring than that induced by the mechanical microkeratome. Further insight with larger series will be required to determine whether the presence or the absence of epithelial cells at the flap margin is associated to more or fewer complications, for example whether an increased incidence of epithelial cell invasion is associated to a weaker flap adhesion.
Keywords: refractive surgery • cornea: stroma and keratocytes • imaging/image analysis: clinical