Instrument to Enhance Visualization of Descemet Membrane During Graft Preparation for DMEK Surgery

Purpose: Descemet membrane (DM) endothelial keratoplasty has improved outcomes of corneal transplantation in patients with corneal endothelial disease. However, the procedure has been criticized for jeopardizing donor tissue during graft preparation. Standardization of this procedure may provide a way toward minimizing tissue loss. For this purpose, we propose the use of a novel tool. Methods: Computerized numerical control milling was used to create a blunt instrument, which was used to remove endothelial cells within a defined area in the periphery of donor corneas. Trypan blue was used to stain denuded DM. Graft preparation was continued as per our standard protocol. Transmission electron microscopy was performed on the treated area, and endothelial cell counts were obtained. Results: Use of the modified procedure resulted in delineation of a peripheral band of denuded DM, which readily stained with trypan blue. This provided increased visibility of DM during subsequent steps. Transmission electron microscopy confirmed that no structural deficits of DM were induced. Mean endothelial cell loss (±SD) at 24 hours after preparation was 63 (±130) cells per square millimeter in the group prepared with the use of the new instrument (n = 7), versus 116 (±107) cells per square millimeter in the group prepared without the new instrument (n = 7; P = 0.45). Conclusions: The device presented here enhances visualization of DM during creation of the peripheral margin for subsequent lifting of the margin and stripping of the graft. This may increase success rates and shorten preparation times and learning periods for DM preparation. DM ultrastructure and endothelial cells were not negatively affected.