title: Use of ultrasonic pachymetry for measurement of changes in corneal thickness in mouse corneal transplant rejection.
abstract: OBJECTIVE
  Diagnosis of rejection in the mouse model of corneal transplantation is based on subjective judgement of loss of graft transparency. The aims of this study were to (1) evaluate a pachymetry technique to measure changes in mouse corneal thickness and (2) correlate increases in transplant thickness with clinical and histological features of rejection.
  
  
  METHODS
  Orthotopic corneal allografts (C57BL/6 strain donor) and syngeneic grafts were performed in A/J mice. Graft transparency was graded and corneal thickness measured by pachymetry on alternate days. Transverse sections of donor cornea excised from eyes representative of clinical opacity grades 1-4 were prepared, photographed, graft section thickness measured and stromal graft-infiltrating cells counted. Intraobserver and interobserver variations in pachymetry were statistically tested.
  
  
  RESULTS
  Graft thickness, as measured by pachymetry, increased with each clinical opacity grade. Thickness for opacity grades 0, 1 and 2 was less than 300 microm in all recipients. Graft thickness for grades 3 and 4 was greater than 300 microm in all cases. For measurements up to 400 mum, there was a good correlation between thickness as measured by in vivo pachymetry and in histopathological sections. The mean interobserver bias was -11.35 microm, while the mean intraobserver bias was +3.96 microm. Stromal cellularity increased with increasing corneal thickness up to approximately 300 microm.
  
  
  CONCLUSIONS
  In vivo graft pachymetry provides a new and reliable way to objectively diagnose rejection in the mouse model of corneal transplantation.
authors.affiliation: Department of Ocular Immunology, UCL Institute of Ophthalmology, London, UK. thomas.flynn@ucl.ac.uk
authors.forename: T H
authors.initials: TH
authors.lastname: Flynn
authors.forename: M
authors.initials: M
authors.lastname: Ohbayashi
authors.forename: M
authors.initials: M
authors.lastname: Dawson
authors.forename: M
authors.initials: M
authors.lastname: Siddique
authors.forename: S J
authors.initials: SJ
authors.lastname: Ono
authors.forename: D F P
authors.initials: DF
authors.lastname: Larkin
mesh_terms: D000818:Animals; D003315:Cornea / Q000473:pathology; D003319:Corneal Stroma / Q000473:pathology; D019781:Corneal Topography / Q000379:methods; D016039:Corneal Transplantation; D015925:Cryopreservation; D003941:Diagnostic Techniques, Ophthalmological; D004195:Disease Models, Animal; D005260:Female; D006084:Graft Rejection / Q000000981:diagnostic imaging* / Q000473:pathology; D051379:Mice; D008805:Mice, Inbred A; D008810:Mice, Inbred C57BL; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D014463:Ultrasonography