Eccentrically Punched Descemet Membrane Endothelial Keratoplasty Grafts Expand the Descemet Membrane Endothelial Keratoplasty Donor Pool: One Eye Bank's Reappraisal of the Central Clear Zone Convention

Abstract

To ascertain whether offsetting the Descemet membrane endothelial keratoplasty (DMEK) punch can expand the donor pool in conjunction with prepunched and preloaded services by recapturing the corneas otherwise excluded by the conventional central clear zone criteria. In this retrospective review of corneas recovered and processed for DMEK by a single eye bank between March 2017 and October 2018, corneas failing to meet the conventional central clear zone requirement during initial evaluation (defined as an area in the central cornea where an 7.5- to 8.0-mm diameter graft can be obtained free of previous surgical scars, Descemet tears, or confined areas of endothelial defects) were further evaluated for offset punching. Corneas with a central endothelial cell density of at least 2000 cells/mm at the initial screening (average of 3 specular images assessed with the center dot method) that had a clear zone of 7.5- to 8.0-mm diameter where a graft could be obtained were designated as eligible for offset punching for either prepunched or preloaded DMEK. A total of 2607 corneas were found to be suitable for DMEK using the conventional central clear zone criteria. An additional 62 corneas were deemed DMEK suitable by offsetting the punch, yielding a 2.4% increase in the availability of DMEK suitable corneas. Offsetting the DMEK punch can recapture corneas otherwise excluded from the DMEK donor pool because of a failure to meet the conventional central clear zone criteria, and by our estimation may help eye banks meet the growing demand for DMEK tissue while maximizing the transplant potential of every cornea.