Endothelial cell density after photorefractive keratectomy for moderate myopia using a 213 nm solid-state laser system

Abstract

Purpose: To evaluate whether photorefractive keratectomy (PRK) for moderate myopia using a solid-state laser with a wavelength of 213 nm alters the corneal endothelial cell density.

Setting: University refractive surgery center.

Methods: The corneal endothelium was analyzed preoperatively and 1, 6, and 12 months postoperatively using corneal confocal microscopy (modified HRT II with a Rostock Cornea Module, Heidelberg Engineering) in 60 eyes (30 patients). Patients were randomized to have myopic PRK using a 213 nm wavelength solid-state laser (study group) or a conventional 193 nm wavelength excimer laser (control group). Three endothelial images were acquired in each of 30 preoperative normal eyes to evaluate the repeatability of endothelial cell density measurements. Repeated-measures analysis of variance was used to compare the variations in endothelial cell density between the 2 lasers and the changes in endothelial cell density over time.

Results: There were no statistically significant differences in sex, age, corneal pachymetry, attempted correction, preoperative endothelial cell density, or postoperative refractive outcomes (uncorrected visual acuity, best spectacle-corrected visual acuity, and spherical equivalent refraction) between the 2 groups (P>.05). The coefficient of repeatability of endothelial cell density was 131 cells/mm(2). The measured endothelial cell count per 1.0 mm(2) did not significantly change up to 1 year postoperatively in either group (both P>.05). No statistically significant difference was found between the 2 groups in any postoperative interval (P>.05).

Conclusion: Photorefractive keratectomy for moderate myopia using a 213 nm wavelength solid-state laser or a conventional 193 nm wavelength excimer laser did not significantly affect corneal endothelial density during the 1-year postoperative period.