title: Theoretical, experimental, and optical coherence tomography (OCT) studies of graft apposition and adhesion in Descemets stripping automated endothelial keratoplasty (DSAEK).
abstract: OBJECTIVE
  To investigate the effects of adhesion promoting surgical adjuncts in Descemets stripping automated endothelial keratoplasty (DSAEK). The effects of air-fill pressure, duration, use of venting incisions and stromal roughening on fluid dispersion, and donor adhesion strength were examined in theoretical, optical coherence tomography (OCT), and strain gauge models of DSAEK.
  
  
  METHODS
  OCT analysis: DSAEK modeled using a microkeratome prepared lenticule inserted under a "recipient" corneo-scleral rim mounted on an artificial anterior chamber. Pressure of 18 mm Hg (n = 6) or 60 mm Hg (n = 6) was applied. The area of interface fluid was measured sequentially. The area of interface fluid before and after opening of venting incisions was measured (n = 6). Adhesion experiments: Direct measurement of adhesion force using a universal testing machine was performed. Peak adhesion after compression at 60 mm Hg/8 minutes, 60 mm Hg/1 minutes, 18 mm Hg/8 minutes, and 18 mm Hg/1 minutes (n = 8 each group) was measured. Subsequently, adhesion after complete removal of interface fluid and after stromal roughening was measured in separate samples (n = 12).
  
  
  RESULTS
  Interface fluid diminishes with time during tamponade at both low and high pressures (P < 0.0001). Pressure had no effect on amount or rate of fluid dispersion. Venting incisions eliminated interface fluid in all samples when opened sufficiently. Adhesion is independent of anterior chamber air tamponade pressure (P = 0.38). Complete removal of interface fluid increases average adhesion (16.0 mN vs. 7.8 mN, P = 0.0001). Roughening of the host stroma increased adhesion (13.8 mN vs. 9.8 mN, P = 0.0034).
  
  
  CONCLUSIONS
  Venting incisions and stromal roughening aid adhesion in DSAEK. Sustained high-pressure anterior chamber air tamponade has no demonstrable effect on measured fluid dispersion or adhesion strength.
authors.affiliation: Department of Cornea and External Diseases, Moorfields Eye Hospital, London, UK. manibhogal@aol.com
authors.forename: Maninder S
authors.initials: MS
authors.lastname: Bhogal
authors.forename: Romesh I
authors.initials: RI
authors.lastname: Angunawela
authors.forename: Emiliano
authors.initials: E
authors.lastname: Bilotti
authors.forename: Ian
authors.initials: I
authors.lastname: Eames
authors.forename: Bruce D
authors.initials: BD
authors.lastname: Allan
mesh_terms: D001082:Aqueous Humor / Q000502:physiology; D003319:Corneal Stroma / Q000601:surgery; D003886:Descemet Membrane / Q000601:surgery*; D057111:Descemet Stripping Endothelial Keratoplasty / Q000379:methods*; D004728:Endothelium, Corneal / Q000637:transplantation*; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D008962:Models, Theoretical; D000267:Tissue Adhesions; D041623:Tomography, Optical Coherence / Q000379:methods*