title: Electron microscopy of surface smoothness of porcine corneas and acrylic plates with four brands of excimer laser.
abstract: OBJECTIVE
  This study compares ablation smoothness patterns produced on four different excimer laser devices available for photorefractive surgery.
  
  
  METHODS
  VISX calibration plastic and porcine cornea were ablated with standard -3.00-D, -6.00-D, and -9.00-D settings using four different excimer lasers: VISX S2 Smooth Scan, Nidek EC-5000, Autonomous Ladar Vision System, and Bausch and Lomb Technolas. Electron microscopy and laser interferometry were used for qualitative evaluation of the ablated surfaces. Corneal ablation surface smoothness was graded by ten independent observers. Calibration plastic ablated surfaces were evaluated quantitatively for smoothness by laser interferometry.
  
  
  RESULTS
  The independent observer assessment of corneal ablation surface smoothness demonstrated that the Autonomous small spot Gaussian profile laser produced the smoothest ablation surfaces, followed by the other broad beam lasers. In comparing ablation smoothness among various refractive powers (-9.00 D, -6.00 D, and -3.00 D), a trend was observed that indicated a correlation of higher refractive settings with decreasing surface smoothness. However, this trend was not statistically significant. The quantitative laser interferometry measurements supported the independent observer ranking of the Autonomous flying small spot ablation profile as the smoothest. However, there were differences between the laser interferometry smoothness rankings and independent observer smoothness rankings.
  
  
  CONCLUSIONS
  There were significant differences in ablation surface smoothness among the four excimer lasers tested.
authors.affiliation: Department of Ophthalmology and Visual Science at the Hermann Eye Center Refractive Surgery Unit, Houston, TX, USA.
authors.forename: Justus W
authors.initials: JW
authors.lastname: Thomas
authors.forename: Shrabanee
authors.initials: S
authors.lastname: Mitra
authors.forename: Alice Z
authors.initials: AZ
authors.lastname: Chuang
authors.forename: Richard W
authors.initials: RW
authors.lastname: Yee
mesh_terms: D000818:Animals; D003315:Cornea / Q000601:surgery* / Q000648:ultrastructure*; D007368:Interferometry; D054018:Lasers, Excimer; D008855:Microscopy, Electron, Scanning; D018903:Photorefractive Keratectomy / Q000379:methods*; D019904:Polymethyl Methacrylate; D013552:Swine
chemical_list: D019904:Polymethyl Methacrylate