Effects of laser in situ keratomileusis (LASIK) on the corneal endothelium3 years postoperatively

PURPOSE: To investigate the effects of laser in situ keratomileusis (LASIK) on the corneal endothelium 3 years postoperatively. METHODS: Patients who were subjects of a previous prospective study (Am J O phthalmol 125:465-471, (April) 1998) were contacted for a follow-up analysi s of the central corneal endothelium, Noncontact specular microscopy was pe rformed 35 to 37 months after LASIK on 52 eyes of 27 patients of the origin al cohort of 98 eyes of 65 patients and six eyes of three patients who were previously lost to follow-up after their initial post-LASIK evaluation, Pa tient age ranged from 29 to 66 years at the time of the original LASIK proc edure. Attempted corrections ranged from 2.25 to 14.5 diopters of myopia, g iving theoretical ablation depths of 182 to 332 mum below the corneal surfa ce. Forty-eight eyes (83%) had a history of preoperative contact lens use ( 3 to 33 years). Central endothelial cell density, coefficient of variation of cell size, and percent of hexagonal cells were analyzed using 72 to 152 cells from each image. Multivariate analysis was used to search for factors that might predict changes in cell density, coefficient of variation, and percent of hexagonal cells. RESULTS: The mean +/- SD preoperative cell density was 2,498 +/- 354 cells per mm(2), the mean coefficient of variation was 0.36 +/- 0.07, and the per cent of hexagonal cells was 58 +/- 6. Three years after surgery there was n o statistically significant change in the mean endothelial cell density (2, 489 +/- 335 cells per mm(2); P = 0.88, paired t test) or the percent of hex agonal cells (60 +/- 7; P = 0.14, paired t test). The mean coefficient of v ariation was significantly lower postoperatively (0.32 +/- 0.04; P = 0.0006 , paired t test); a repeated measures analysis showed that this significant improvement could not be explained by cessation of contact lens wear after LASIK (P = 0.34). Multivariate analysis did not identify any factors that were predictive of change in cell density, coefficient of variation, and pe rcent of hexagonal cells. CONCLUSIONS: Laser in situ keratomileusis for the correction of 2.25 to 14. 5 diopters of myopia had no significant effect on central corneal endotheli al cell density or the percent of hexagonal cells 3 years after surgery. Th e coefficient of variation of cell size improved significantly 3 years afte r surgery, (C) 2001 by Elsevier Science Inc. All rights reserved.