title: Nonmechanical Q-switched erbium:YAG laser trephination for penetrating keratoplasty: experimental study on human donor corneas.
abstract: OBJECTIVE
  To assess the alterations in human donor corneal tissue induced by Q-switched erbium (Er):YAG laser corneal trephination.
  
  
  METHODS
  Thirty human corneoscleral donor buttons unsuitable for transplantation were placed in an artificial chamber on an automated rotation device. Corneas were trephined with a Q-switched Er:YAG laser (wavelength, 2.94 microm; pulse duration, 400 nanoseconds) along (donor and recipient) aluminum silicate (ceramic) open masks. A spot diameter of 0.65 mm, energy setting of 50 mJ/pulse, and repetition rate of 5 Hz were used. Corneal thermal damage and cut regularity were quantitatively assessed in 24 corneas processed for light microscopy and by transmission and scanning electron microscopy.
  
  
  RESULTS
  The stromal thermal damage was the highest (mean [SD], 8.0 [2.7] microm) at a 150-microm cut depth and decreased downward. Cut regularity was very good and did not significantly differ between donors and recipients. Scanning electron microscopy confirmed that the cuts were highly regular; transmission electron microscopy revealed 2 distinctive subzones within the stromal thermal damage zone.
  
  
  CONCLUSIONS
  Thermal damage induced by Q-switched Er:YAG nonmechanical corneal trephination was low, and the regularity of the cuts was very good.
  
  
  CONCLUSIONS
  The Q-switched Er:YAG laser may have the potential to become an alternative to the excimer laser for nonmechanical penetrating keratoplasty.
authors.affiliation: Department of Ophthalmology, Friedrich Alexander Universität -- Erlangen-Nürnberg, Erlangen, Germany.
authors.forename: Milenko
authors.initials: M
authors.lastname: Stojkovic
authors.forename: Michael
authors.initials: M
authors.lastname: Küchle
authors.forename: Berthold
authors.initials: B
authors.lastname: Seitz
authors.forename: Achim
authors.initials: A
authors.lastname: Langenbucher
authors.forename: Arne
authors.initials: A
authors.lastname: Viestenz
authors.forename: Anja
authors.initials: A
authors.lastname: Viestenz
authors.forename: Carmen
authors.initials: C
authors.lastname: Hofmann-Rummelt
authors.forename: Ursula
authors.initials: U
authors.lastname: Schlötzer-Schrehardt
authors.forename: Gottfried O H
authors.initials: GO
authors.lastname: Naumann
mesh_terms: D003315:Cornea / Q000601:surgery* / Q000648:ultrastructure; D003319:Corneal Stroma / Q000293:injuries / Q000648:ultrastructure; D004728:Endothelium, Corneal / Q000293:injuries / Q000648:ultrastructure; D006801:Humans; D015948:Keratoplasty, Penetrating / Q000295:instrumentation / Q000379:methods*; D053685:Laser Therapy / Q000009:adverse effects / Q000379:methods*; D014019:Tissue Donors