Corneal endothelial cell changes 5 years after laser in situ keratomileusis: Femtosecond laser versus mechanical microkeratome

Abstract

To compare corneal endothelial cell density (ECD) and morphology between flap creation with a femtosecond laser and flap creation with a mechanical microkeratome 5 years after laser in situ keratomileusis (LASIK). Mayo Clinic, Rochester, Minnesota, USA. Prospective randomized masked paired-eye study. In this study of LASIK for myopia or myopic astigmatism, fellow eyes were randomized by ocular dominance to flap creation by a femtosecond laser or by a mechanical microkeratome. Central endothelial images were analyzed before and 3 years and 5 years after LASIK; endothelial cell variables were compared between treatments at each examination. Relationships between endothelial cell loss and contact lens wear, residual bed thickness, and preoperative refractive error were evaluated. There were no differences in the ECD, percentage of hexagonal cells, or coefficient of variation of cell area between treatments at any examination (all P = .99); the smallest detectable differences were 120 cells/mm(2), 5%, and 2%, respectively. The mean annual rate of corneal endothelial cell loss was -0.1% ± 1.2% (SD) and -0.1% ± 1.0% for the femtosecond laser and the mechanical microkeratome, respectively. Endothelial cell loss was not associated with contact lens wear, residual bed thickness, or preoperative refractive error. The energy delivered to the cornea during femtosecond laser flap creation did not affect the corneal endothelium 5 years after LASIK when compared with flap creation with a mechanical microkeratome. Corneas that have had either method of flap creation could be accepted as donor tissue for endothelial keratoplasty from the standpoint of endothelial health. No author has a financial or proprietary interest in any material or method mentioned.