Anterior chamber fibrin reaction during Descemet membrane endothelial keratoplasty

PURPOSE: To report a series of five cases of intraoperative spontaneous anterior chamber fibrin reaction during Descemet Membrane Endothelial Keratoplasty (DMEK). METHODS: We retrospectively collected demographic data and data for ocular disease history for each patient. Donor age, preoperative graft endothelial density, surgical complications on surgery and intraoperative OCT videos, intraoperative management and outcome were assessed. The same standardized DMEK technique was used for all patients. RESULTS: We report intraoperative fibrin formation in five eyes subjected to DMEK. Three pseudophakic eyes underwent single DMEK, and the other two underwent combined DMEK and cataract surgery. In one case, a fibrin filament was observed before graft insertion, with multiplication during surgery, whereas, in the other four cases, strands of fibrin from the iris appeared after graft insertion. This complication resulted in graft failure in four cases (80%). No recipient- or donor-related risk factor was identified. CONCLUSIONS AND IMPORTANCE: The anterior chamber fibrin reaction is a very uncommon complication of DMEK. The underlying pathophysiological mechanisms remain unknown, but analyses of surgical videos and intraoperative OCT suggest iris involvement. This phenomenon may be induced by chronic subclinical anterior chamber inflammation, due to a blood-aqueous barrier breakdown associated with acute iris trauma during surgery. Thus, intraoperative microtraumatism of the iris should be avoided.