Donor tissue impact on Descemet Membrane Endothelial Keratoplasty (DMEK) graft preparation and clinical outcome

Introduction: To determine which donor characteristics, like previous diseases and surgeries, influence the graft preparation difficulty of the Descemet membrane (DM)/endothelial lamella in DMEK-surgery and to analyze the impact on the one-year clinical outcome. Methods: 1051 eyes with DMEK-surgery between 01/2018 and 01/2021 performed at the University Hospital Cologne, Germany were included in this single-center and retrospective study. Information regarding the donors’ previous diseases and surgeries were provided by a large database of a cornea bank (Multi Tissue Bank Mecklenburg-Vorpommern) and merged with the Cologne DMEK database, that contains information regarding preparation characteristics of the surgeon-prepared graft directly preoperatively and postoperative clinical follow-up. Three preparation groups (easy, difficult and very difficult) were correlated to the donors’ previous disease and surgeries. Also, outcome parameters, like visual acuity, endothelial cell density and graft survival were correlated to the graft preparation group. Results: Donor diabetes was found as significant predictor for central adhesions (p<0.001). Diabetes patients are 2-times more likely to have central adhesions complicating preparation than non-diabetes patients (OR =2.2). Previous cataract surgery was significantly associated with difficult stripping and preparation (p <0.001), with an estimated 1.07 fold increase in stripping difficulty (95% CI 0.80-1.34) and overall 1.99 fold increase in preparation difficulty (95% CI 1.71-2.29). Chronic kidney disease (p=0.012) and previous cataract-surgery (p=0.005) show significant associations to tissue loss. Donor diagnosis such as Diabetes Mellitus type 2, chronic ischemic heart disease and respiratory insufficiency have a significant association with the preparation group (p=0.001; p=.004 and p=0.032, respectively). No interactions were found between preparation difficulties and visual acuity (p=0.122), rebubbling rate (p=0.780) or endothelial cell density (p=0.886) nor graft survival (p value=0.157) one year postoperatively. Conclusions: Donor diabetes mellitus, heart failure, hypertension, respiratory insufficiency, kidney disease and previous cataract surgery are associated with difficult DMEK graft preparation, the latter two also with tissue loss. No impact of donor factors on clinical outcome was found.