title: Photorefractive keratectomy using solid state laser 213 nm and excimer laser 193 nm: a randomized, contralateral, comparative, experimental study.
abstract: OBJECTIVE
  To compare histopathologic changes after photorefractive keratectomy (PRK) for myopia using either a solid state laser (SSL) at 213 nm or an excimer laser (EL) at 193 nm in an experimental model.
  
  
  METHODS
  Forty pigmented rabbits (80 eyes) underwent myopic PRK for the correction of 6 D. Photoablation was randomly assigned, with a solid state laser used in one eye and an EL in the fellow eye. Rabbits were killed immediately after ablation (n = 10) or at 7 days (n = 10), 1 month (n = 8), 3 months (n = 6), or 12 months (n = 6) after surgery. Corneal tissue was preserved for light microscopy and transmission electron microscopy at all postoperative intervals.
  
  
  RESULTS
  All eyes reepithelialized in 1 week with no early or late postoperative complication. Immediately after ablation, light, scanning, and transmission electron microscopy revealed relatively smooth ablation surfaces in both groups. Seven days after surgery, epithelium in the SSL specimens appeared thinner than in the EL specimens. Activated keratocytes were observed adjacent to the epithelium in both groups, whereas endothelial cells demonstrated normal morphology. At 1, 3, and 12 months after surgery, tissue appearance of all corneal layers was similar in both groups.
  
  
  CONCLUSIONS
  PRK in rabbits using ultraviolet SSL and EL revealed similar histopathologic findings up to 1 year after surgery.
authors.affiliation: Department of Ophthalmology, Institute of Vision and Optics, University of Crete Medical School, Heraklion, 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: George A
authors.initials: GA
authors.lastname: Kounis
authors.forename: Irini I
authors.initials: II
authors.lastname: Naoumidi
authors.forename: Ioannis G
authors.initials: IG
authors.lastname: Pallikaris
mesh_terms: D000818:Animals; D003315:Cornea / Q000601:surgery* / Q000648:ultrastructure; D003319:Corneal Stroma / Q000648:ultrastructure; D004195:Disease Models, Animal; D019573:Epithelium, Corneal / Q000648:ultrastructure; D005260:Female; D054018:Lasers, Excimer; D053844:Lasers, Solid-State; D008297:Male; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D009216:Myopia / Q000473:pathology / Q000601:surgery*; D018903:Photorefractive Keratectomy / Q000379:methods*; D011817:Rabbits; D011897:Random Allocation