title: Free-running erbium:YAG laser for nonmechanical trephination in penetrating keratoplasty: first results of experimental trephination of human donor corneas.
abstract: BACKGROUND
  A study was carried out to evaluate the potential suitability of a free-running erbium:YAG 2.94-microm laser for trephination of human corneas in penetrating keratoplasty.
  
  
  METHODS
  Two human donor corneas were placed in an artificial anterior chamber and moved with an automated rotation device (one rotation per minute). An erbium:YAG laser beam (pulse duration 400 micros, repetition rate 2/s, energy density 2.5 and 15.0 J/cm(2)) was focused on the outer edge of a round ceramic mask placed on the human donor corneas for ablation of tissue.
  
  
  RESULTS
  With a fluence of 15.0 J/cm(2), perforation was achieved after 500 pulses. Perpendicular central cut edges with mild stromal ridges and, by light microscopy, a 12 to 45-microm area of stromal thermal effects and focal endothelial changes up to 200 microm central to trephination were observed.
  
  
  CONCLUSIONS
  The erbium:YAG laser could be a promising "low-cost alternative" to the excimer laser for nonmechanical trephination in penetrating keratoplasty. Further studies will have to focus on reduction of thermal damage and on wound healing.
authors.affiliation: Department of Ophthalmology and University Eye Hospital, University Erlangen-Nürnberg, Schwabachanlage 6, D-91054 Erlangen, Germany. michael.kuechle@augen.med.uni-erlangen.de
authors.forename: M
authors.initials: M
authors.lastname: Küchle
authors.forename: A
authors.initials: A
authors.lastname: Behrens
authors.forename: B
authors.initials: B
authors.lastname: Seitz
authors.forename: A
authors.initials: A
authors.lastname: Langenbucher
authors.forename: G O
authors.initials: GO
authors.lastname: Naumann
mesh_terms: D000818:Animals; D002102:Cadaver; D003315:Cornea / Q000166:cytology / Q000601:surgery*; D006801:Humans; D066298:In Vitro Techniques; D015948:Keratoplasty, Penetrating / Q000379:methods*; D053685:Laser Therapy; D008875:Middle Aged; D013552:Swine; D014019:Tissue Donors