1. Effect of Donor Processing and Storage Time and Preoperative Endothelial Cell Counts on DSAEK Detachment Rates Daniel Demsey BScE Stephanie Baxter MD, FRCSC Queen’s University School of Medicine, Department of Ophthalmology. Kingston, ON, Canada The authors have no financial interest in the subject matter of this poster.

2. Rationale To determine whether the rate of graft detachment in patients undergoing the DSAEK procedure is influenced by the time elapsed between donor death, tissue procurement, processing, storage, and implantation, as well as endothelial cell count, in one surgeon’s practice.

3. Introduction The DSAEK procedure is primarily used to treat corneal endothelial dystrophies 1, and more recently to treat endothelial failure in previous penetrating keratoplasty, irido- corneal-endothelial (ICE) syndrome, aphakia, aniridia, and complex anterior segments with anterior chamber lenses 2. Descemet’s membrane and endothelium are removed through a small incision and replaced with donor tissue, which adheres to the recipient’s inner corneal stroma 1. The major post-operative complication of the DSAEK procedure is dislocation of the donor tissue from the corneal transplant bed, which has been reported to happen in 4-27% of patients 1,5,8,10,11. Donor detachments are most likely attributed to surgeon error or a lack of donor tissue viability.

4. Introduction In Ontario, Canada donor tissue is procured from cadavers and sent to the Eye Bank of Canada, Ontario Division in Toronto before being shipped to the transplanting surgeons for implantation in a patient. A period of time, typically hours, passes between the death of the donor and enucleation of the eye, and between enucleation and processing by the Eye Bank. The tissue then spends a period of days in storage at the Eye Bank before implantation in the recipient eye. Currently all DSAEK donor tissue is currently prepared by individual surgeon’s at the site and time of transplantation.

5. Hypothesis It is our hypothesis that a greater period of time spent in storage or prior to processing results in a potentially greater loss of tissue viability and concordantly leads to a higher rate of detachment post operatively. Additionally, it is hypothesized that the endothelial cell count of the donor tissue plays a role in detachment rate, with a higher count possibly indicating better tissue function and thus a lower detachment rate. The primary aim of our investigation is to determine whether these factors play a predictive role in tissue detachment in one surgeon’s practice.

6. Methods Data on procedure outcome and donor tissue for all patients in one surgeon’s practice undergoing the DSAEK procedure between April 1, 2007 and April 30, 2010 was reviewed through a retrospective chart review. Data on time elapsed between harvest, processing, storage, and implantation of the tissue was obtained from reports made available from the Eye Bank of Canada, Ontario Division. The adverse outcome of interest was graft detachment requiring re-bubbling.

7. Results No DetachmentSDDetachmentSDP N6110 Time to Procurement (hours)6.23.57.44.00.36 Time to Processing (hours)13.15.913.56.30.87 Time in Bank (days)3.92.24.62.20.36 Cell Count2647.4244.52776.5299.50.14

8. Results 71 cases were reviewed, with 14% resulting in dislocation. Averages were determined of the time between donor death and tissue procurement, procurement and processing, storage at the Eye Bank, and implantation in the recipient, as well as endothelial cell count, and compared between the grafts that failed and those that did not using a paired student’s t-test. There was no statistically significant difference in any of these parameters between the two groups.

9. Discussion As demonstrated in the results section, there was no statistically significant difference in the storage and processing times between the detachment and non-detachment groups. This suggests that slight variations in donor tissue processing and storage times do not result in a higher incidence of DSAEK graft dislocation.

10. Conclusions The range of processing times and endothelial cell counts in donor tissue available from the Eye Bank did not predict a change in the rate of graft dislocation in one surgeon’s practice.

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