title: Manual suction versus femtosecond laser trephination for penetrating keratoplasty: intraocular pressure, endothelial cell damage, incision geometry, and wound healing responses.
abstract: OBJECTIVE
  To measure real-time intraocular pressure (IOP) during trephination with a manual suction trephine (MST) and the femtosecond laser (FSL), and to assess endothelial cell damage, incision geometry, and wound healing response with these procedures.
  
  
  METHODS
  IOP was monitored with an intracameral sensor. Eight rabbits underwent manual suction trephination. Eight rabbits had FSL trephination (FSL-T). Slit lamp photography, confocal microscopy, and anterior segment optical coherence tomography (AS-OCT) were performed at baseline and postoperatively. Animals were sacrificed at 4 hours and 3 days. Tissue was examined with scanning electron microscopy (SEM) and immunohistochemistry for an array of wound-healing markers. Separately, 6 human corneas had MST (3) and FSL-T (3). Incision geometry was imaged with high resolution Optovue AS-OCT.
  
  
  RESULTS
  The average IOP during MST and FSL-T was similar (37 mm Hg). There was wider IOP fluctuation during the MST cutting phase (60 mm Hg maximum). There were 1-2 rows of endothelial loss on either side of the incision for FSL-T and 2-5 rows deep for MST. Immune cell responses at 4 hours (CD11b) were comparable, greater apoptosis with FSL-T (TUNEL) occurred at 4 hours, and there was increased keratocyte proliferation at 3 days (Ki67) with FSL-T. There was significantly greater undercutting of the cornea with MST (46.86 degrees versus 16.72 degrees).
  
  
  CONCLUSIONS
  There is more IOP variation during MST. Average IOP is 37 mm Hg for both techniques. More endothelial damage and undercutting of the cornea occurs with MST. The wound healing response to FSL-T appears greater at 3 days.
authors.affiliation: Singapore National Eye Centre, 11 Third Hospital Avenue, Singapore.
authors.forename: Romesh I
authors.initials: RI
authors.lastname: Angunawela
authors.forename: Andri
authors.initials: A
authors.lastname: Riau
authors.forename: Shyam S
authors.initials: SS
authors.lastname: Chaurasia
authors.forename: Donald T
authors.initials: DT
authors.lastname: Tan
authors.forename: Jodhbir S
authors.initials: JS
authors.lastname: Mehta
mesh_terms: D000328:Adult; D000368:Aged; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002452:Cell Count; D003315:Cornea / Q000601:surgery*; D055954:Corneal Endothelial Cell Loss / Q000175:diagnosis* / Q000378:metabolism; D004728:Endothelium, Corneal / Q000473:pathology; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D020287:In Situ Nick-End Labeling; D007429:Intraocular Pressure / Q000502:physiology*; D015948:Keratoplasty, Penetrating / Q000379:methods*; D053685:Laser Therapy / Q000379:methods*; D008297:Male; D008855:Microscopy, Electron, Scanning; D008875:Middle Aged; D011817:Rabbits; D013396:Suction / Q000379:methods*; D041623:Tomography, Optical Coherence; D014945:Wound Healing / Q000502:physiology*; D055815:Young Adult
chemical_list: D015415:Biomarkers