title: Human corneal ablation threshold using the 193-nm ArF excimer laser.
abstract: OBJECTIVE
  To determine the human corneal threshold ablation energy density for the 193-nm ArF excimer laser, approximating clinical conditions.
  
  
  METHODS
  The VISX Star (Santa Clara, CA) 193-nm argon fluoride excimer laser was used to ablate the cornea in human eye bank eyes under clinical conditions. Corneas were exposed to energy densities of 10, 20, 30, 35, 40, 45, and 140 to 160 mJ/cm2. Corneas were fixed for light and transmission electron microscopy immediately after laser exposure.
  
  
  RESULTS
  Different ablation thresholds for various corneal structural elements were observed. The ablation threshold for the collagen in the corneal stroma was determined to be 30 mJ/cm2. Keratocytes had ablation thresholds of 40 mJ/cm2. These different ablation thresholds accounted for the production of stromal peaks and valleys, with the keratocytes atop the peaks.
  
  
  CONCLUSIONS
  Different corneal structural elements have different ablation threshold energy densities.
authors: Beckman Laser Institute, University of California-Irvine, 92612, USA.
authors: M W
authors: MW
authors: Berns
authors: L
authors: L
authors: Chao
authors: A W
authors: AW
authors: Giebel
authors: L H
authors: LH
authors: Liaw
authors: J
authors: J
authors: Andrews
authors: B
authors: B
authors: VerSteeg
mesh_terms: D003094:Collagen / Q000378:metabolism; D003315:Cornea / Q000378:metabolism / Q000473:pathology* / Q000601:surgery*; D003319:Corneal Stroma / Q000378:metabolism / Q000473:pathology; D005347:Fibroblasts / Q000473:pathology; D006801:Humans; D054018:Lasers, Excimer; D018903:Photorefractive Keratectomy
chemical_list: D003094:Collagen