title: Laboratory Evaluation of Femtosecond Laser Lamellar Cuts in Gamma-Irradiated Corneas.
abstract: OBJECTIVE
  To evaluate the stromal interface quality after femtosecond laser full lamellar cuts in gamma-irradiated corneas (VisionGraft sterile cornea) and to determine the limits of the cut depth using the VisionGraft as donor corneas for laser-assisted lamellar anterior keratoplasty.
  
  
  METHODS
  Fourteen VisionGraft corneas underwent full lamellar cuts using the femtosecond laser. The percent cut depth was 17% to 21% (100 μm, n = 2), 31% to 35% (n = 3), 38% to 40% (n = 3), 45% to 48% (n = 3), and 50% (n = 3) of the total stromal thickness (not including the epithelium). The cap and stromal bed surfaces were imaged with a scanning electron microscope. The quality of cut surfaces was graded by 2 masked observers based on two indices: ridge and roughness. Ridge grading indicated macroscopic irregularity. Roughness grading indicated microscopic irregularity. The grading was done on a subjective integer scale of 1 to 5 (1 = best and 5 = worst), which was used in a previous study of cut quality in fresh corneas.
  
  
  RESULTS
  The ridge grading ranged from 1.5 for the shallowest cut to 2.2 for the deepest cut and weakly (r = 0.279) but significantly (P = 0.037) correlated with the percent cut depth. The roughness grading ranged from 2.63 to 2.56 and showed no trend with the percent cut depth (r = 0.006, P = 0.968).
  
  
  CONCLUSIONS
  Compared with previously published results of fresh corneas, in which ridge grading exceeded 3 for cuts deeper than 31%, cut quality was better for the VisionGraft. Even at depths up to 48% of the total stromal thickness, ridge grading was not worse than shallow cuts. Thus, gamma-irradiated corneas could provide a smoother interface than do fresh eye bank corneas for laser-assisted lamellar anterior keratoplasty.
authors.affiliation: *Center for Ophthalmic Optics and Lasers, Casey Eye Institute, Portland, OR; †Department of Ophthalmology, Oregon Health and Science University, Portland, OR; ‡Department of Ophthalmology, Southwest Eye Hospital, Third Military Medical University, Chongqing, China; and §Department of Ophthalmology, Peking Union Medical College Hospital, Beijing, China.
authors.forename: Chenxing
authors.initials: C
authors.lastname: Zhang
authors.forename: Liang
authors.initials: L
authors.lastname: Liu
authors.forename: Maolong
authors.initials: M
authors.lastname: Tang
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.forename: Winston
authors.initials: W
authors.lastname: Chamberlain
authors.forename: David
authors.initials: D
authors.lastname: Huang
mesh_terms: D003315:Cornea / Q000528:radiation effects* / Q000601:surgery*; D003319:Corneal Stroma / Q000648:ultrastructure*; D048988:Corneal Surgery, Laser / Q000379:methods*; D016039:Corneal Transplantation / Q000379:methods*; D005720:Gamma Rays; D006801:Humans; D008855:Microscopy, Electron, Scanning; D014019:Tissue Donors; D041623:Tomography, Optical Coherence