Endothelial cell density after photorefractive keratectomy for moderate myopia using a 213 nm solid-state laser system
Accepted 11 June 2007.
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/mm2. The measured endothelial cell count per 1.0 mm2 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.
From the Department of Ophthalmology (Tsiklis, Kymionis, I.G. Pallikaris) and Institute of Vision and Optics (Tsiklis, Kymionis, A.I. Pallikaris, Diakonis, Ginis, Kounis, Panagopoulou, I.G. Pallikaris), University of Crete, Crete, Greece
Corresponding author: Nikolaos S. Tsiklis, MD, MSc, Institute of Vision and Optics, University of Crete, Medical School, Department of Ophthalmology, 71003 Heraklion, Crete, Greece.
No author has a financial or proprietary interest in any material or method mentioned.
ABSTRACT