title: Endothelial cell density after photorefractive keratectomy for moderate myopia using a 213 nm solid-state laser system.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Ophthalmology, University of Crete, Crete, Greece. ntsiklis@hotmail.com
authors.forename: Nikolaos S
authors.initials: NS
authors.lastname: Tsiklis
authors.forename: George D
authors.initials: GD
authors.lastname: Kymionis
authors.forename: Aristofanis I
authors.initials: AI
authors.lastname: Pallikaris
authors.forename: Vasilios F
authors.initials: VF
authors.lastname: Diakonis
authors.forename: Harilaos S
authors.initials: HS
authors.lastname: Ginis
authors.forename: George A
authors.initials: GA
authors.lastname: Kounis
authors.forename: Sophia I
authors.initials: SI
authors.lastname: Panagopoulou
authors.forename: Ioannis G
authors.initials: IG
authors.lastname: Pallikaris
mesh_terms: D000293:Adolescent; D000328:Adult; D002452:Cell Count; D004728:Endothelium, Corneal / Q000473:pathology*; D005260:Female; D006801:Humans; D054018:Lasers, Excimer; D053844:Lasers, Solid-State; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000601:surgery*; D018903:Photorefractive Keratectomy; D011446:Prospective Studies