Effects of laser in situ keratomileusis (LASIK) on the corneal endothelium 3 years postoperatively

Abstract

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 Ophthalmol 125:465–471, (April) 1998) were contacted for a follow-up analysis of the central corneal endothelium. Noncontact specular microscopy was performed 35 to 37 months after LASIK on 52 eyes of 27 patients of the original 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. Patient age ranged from 29 to 66 years at the time of the original LASIK procedure. Attempted corrections ranged from 2.25 to 14.5 diopters of myopia, giving theoretical ablation depths of 182 to 332 μm below the corneal surface. 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 percent of hexagonal cells was 58 ± 6. Three years after surgery there was no 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 hexagonal cells (60 ± 7; P = 0.14, paired t test). The mean coefficient of variation 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 percent 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 endothelial cell density or the percent of hexagonal cells 3 years after surgery. The coefficient of variation of cell size improved significantly 3 years after surgery.