Technical Procedures Necessary to Achieve Successful Endothelial Keratoplasty Using Human Donor Tissue in a Cat Model

Abstract

Purpose: To develop an appropriate surgical technique in the cat for studies evaluating the safety and efficacy of candidate products designed to treat corneal endothelial dystrophy. To demonstrate that DSEK with human donor tissue can be successfully performed on a cat model and thereby validate the cat as an appropriate testing ground for a bioengineered corneal transplant substitute.

Methods: DSEK surgery was performed on the right eye of 5 cats using human donor tissue. A single, fellowship-trained corneal surgeon performed all surgeries. Animals were treated in compliance with the guidelines set forth by ARVO. Human corneal endothelial cells and the posterior stroma from cadaveric human eyes donated to eye banks were used and prepared in the same fashion used for human surgery. The surgical technique performed was as similar to that performed on humans as possible. The folllowing modifications were made: (1) lateral canthotomy and placement of stay sutures; (2) destruction of endothelial cells and Descemet’s membrane instead of removing them; (3) stabilization of the implant with through-and-through corneal/implant sutures;(4) Supine positioning of animals postoperatively for 1 hour rather than 24 hours. The animals were observed for 8 weeks postoperatively, at which time they were euthanized and the eyes submitted for histologic examination. Corneal pachymetry and corneal clarity were assessed weekly. Slit lamp photos were taken weekly.

Results: All animals tolerated the procedure well and completed the study. Three out of 5 eyes regained clarity as evidenced by photography and subjective measure. 2 out of 5 eyes had significant scarring of the graft. Histology demonstrated good adherence of the graft with little intra-ocular inflammation in all 5 eyes.

Conclusions: The cat is a viable model for DSEK surgery using human donor tissue. Slight modifications to the procedure as done in humans proved necessary in cats to increase the success of the surgery. The cat model is a potential testing ground for bioengineered corneal donor substitutes.

Keywords: 481 cornea: endothelium • 741 transplantation