title: Corneal surface morphology following excimer laser ablation with humidified gases.
abstract: OBJECTIVE
  To compare the effects of blowing dry (nitrogen or helium) and humidified gases over the corneal surface during photorefractive keratectomy.
  
  
  METHODS
  Excimer laser myopic ablations were performed on porcine eyes (10 per group) using humidified and dry nitrogen and helium gas under ambient conditions. Surface smoothness was quantified with light and electron microscopy.
  
  
  RESULTS
  Corneas that were ablated using humidified gas were smooth and equivalent to those ablated under ambient conditions. Dry nitrogen and helium blowing resulted in increased surface irregularity evident on light and electron microscopy (P < .001). The pseudomembranes in the humidified gas and ambient air groups had fewer surface discontinuities than did those in the nonhumdified gas groups and appeared to have a thinner electron-dense surface layer.
  
  
  CONCLUSIONS
  The blowing of humidified gas during excimer laser corneal ablation produces a smoother surface than does the blowing of dry gas and is comparable to that produced under ambient (no blowing) conditions. Maintaining corneal moisture is important in photorefractive keratectomy. If blowing gas is necessary to remove debris from the surface, the gas should be humidified.
authors.affiliation: Doheny Eye Institute, Los Angeles.
authors.forename: R R
authors.initials: RR
authors.lastname: Krueger
authors.forename: M
authors.initials: M
authors.lastname: Campos
authors.forename: X W
authors.initials: XW
authors.lastname: Wang
authors.forename: M
authors.initials: M
authors.lastname: Lee
authors.forename: P J
authors.initials: PJ
authors.lastname: McDonnell
mesh_terms: D000818:Animals; D003315:Cornea / Q000601:surgery* / Q000648:ultrastructure*; D006371:Helium; D006813:Humidity; D007091:Image Processing, Computer-Assisted; D053685:Laser Therapy / Q000379:methods*; D008855:Microscopy, Electron, Scanning; D009216:Myopia / Q000601:surgery; D009584:Nitrogen; D013552:Swine
chemical_list: D006371:Helium; D009584:Nitrogen