title: Surface quality of femtosecond dissected posterior human corneal stroma investigated with atomic force microscopy.
abstract: OBJECTIVE
  To investigate and compare the surface roughness and morphology of posterior stromal lenticules created with a femtosecond laser using various pulse energies to that obtained with a mechanical microkeratome.
  
  
  METHODS
  A 150 kHz femtosecond laser platform (IntraLase iFS; Abbott Medical Optics) was programmed to create an 8.5-mm-diameter posterior stromal lenticule in 12 human corneal tissues. Specimens were dissected using different pulse energies (1.00, 0.75, 0.65, and 0.50) and fixed 2 μm spot separations. Three additional posterior corneal lenticules were prepared using a mechanical microkeratome (Moria Evolution 3; Moria). After the procedure, each corneal tissue was examined by atomic force microscopy (Autoprobe CP; Veeco).
  
  
  RESULTS
  Femtosecond laser-treated tissues revealed similar morphological features, however, with significant differences in surface roughness in relation to the energy pulse used for lamellar dissection (P<0.001). The most regular stromal surface was achieved when using 0.50 μJ pulse energy; on the contrary, the roughest specimens were those dissected using 1.00 μJ pulse energy. No differences in surface roughness were measured between mechanically resected tissues and those treated using 0.50 μJ pulse energy (P>0.05).
  
  
  CONCLUSIONS
  Atomic force microscopy submicron analysis of femtosecond-dissected donor tissues provided quantitative demonstration of the relation between pulse energy and stromal surface roughness. Surface quality of posterior corneal lenticules, comparable with that provided by mechanical microkeratome, is significantly improved when setting pulse energy for lamellar dissection of 0.50-μJ and 2-μm spot separations.
authors.affiliation: IRCCS Fondazione G.B. Bietti, Rome, Italy. mlombardo@visioeng.it
authors.forename: Marco
authors.initials: M
authors.lastname: Lombardo
authors.forename: Maria P
authors.initials: MP
authors.lastname: De Santo
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Lombardo
authors.forename: Domenico
authors.initials: D
authors.lastname: Schiano Lomoriello
authors.forename: Giovanni
authors.initials: G
authors.lastname: Desiderio
authors.forename: Pietro
authors.initials: P
authors.lastname: Ducoli
authors.forename: Riccardo
authors.initials: R
authors.lastname: Barberi
authors.forename: Sebastiano
authors.initials: S
authors.lastname: Serrao
mesh_terms: D000368:Aged; D002452:Cell Count; D003319:Corneal Stroma / Q000473:pathology* / Q000601:surgery; D057111:Descemet Stripping Endothelial Keratoplasty; D004210:Dissection / Q000379:methods; D004728:Endothelium, Corneal / Q000473:pathology; D006801:Humans; D053685:Laser Therapy; D018625:Microscopy, Atomic Force; D013499:Surface Properties; D014019:Tissue Donors