Use of ultrasonic pachymetry for measurement of changes in corneal thickness in mouse corneal transplant rejection
- 1Department of Ocular Immunology, UCL Institute of Ophthalmology, London, UK
- 2Moorfields Eye Hospital, City Road, London, UK
- 3Dobbs Ocular Immunology Laboratories, Emory Eye Center, Emory University, Atlanta, Georgia, USA
- Correspondence to Mr Tom Flynn, Moorfields Eye Hospital, 162 City Road, London EC1V 2PD, UK;
- Accepted 5 September 2009
- Published Online First 12 October 2009
Background/aims 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 μm in all recipients. Graft thickness for grades 3 and 4 was greater than 300 μm in all cases. For measurements up to 400 μm, there was a good correlation between thickness as measured by in vivo pachymetry and in histopathological sections. The mean interobserver bias was −11.35 μm, while the mean intraobserver bias was +3.96 μm. Stromal cellularity increased with increasing corneal thickness up to approximately 300 μm.
Conclusion In vivo graft pachymetry provides a new and reliable way to objectively diagnose rejection in the mouse model of corneal transplantation.
Funding This research was supported by Fight for Sight, Special Trustees of Moorfields Eye Hospital, and an Irish College of Ophthalmologists/Pfizer research fellowship award.
Competing interests None.
Provenance and peer review Not commissioned; externally peer reviewed.