Evaluation of Total Donor Endothelial Viability After Endothelium-Inward Versus Endothelium-Outward Loading and Insertion in Descemet Membrane Endothelial Keratoplasty

Abstract

PURPOSE: This study compares endothelial cell density (ECD) and viability between 2 different techniques used to prepare and insert Descemet membrane endothelial keratoplasty (DMEK) donor tissues. The first technique uses the naturally forming Descemet membrane (DM) scroll where the endothelial cells face outward; in the second technique, the DM is folded into thirds (trifold) with the endothelial cells facing inward. METHODS: Eighteen cadaveric corneas from 9 donors (matched pairs) were used to compare the 2 tissue-insertion techniques. In the scroll, endothelium-outward technique, standard DMEK preparation was used, and the naturally forming DM scroll was inserted into a Geuder Cartridge. In the trifold, endothelium-inward technique, DMEK preparation was undertaken by folding the donor tissue into thirds before being pulled into the EndoGlide Ultrathin. In each case, the tissue was injected onto a glass slide. Endothelial cell counting was performed using microscopy preinjection and postinjection, and vital staining using calcein acetoxymethyl (AM) was used for quantitative cell viability analysis across the whole tissue. RESULTS: Manual ECDs using direct microscopy did not demonstrate a statistically significant difference in ECD between the 2 injection techniques. Using vital staining of the entire 8.0-mm diameter tissue, there was a significantly higher percentage of viable cells using the trifold, endothelium-inward technique (63.1%) compared with the scroll, endothelium-outward technique (41.5%) (P = 0.013). There was no difference in the pattern of cell loss between the 2 groups. CONCLUSIONS: Greater endothelial cell viability was observed using the trifold, endothelium-inward technique compared with the scroll, endothelium-outward technique.