Effect of Proteolytic Enzymes on Descemet Membrane Endothelial Keratoplasty (DMEK) Graft Elasticity

Purpose To investigate the proteolytic effect on Descemet membrane endothelial keratoplasty (DMEK) graft elasticity.Methods The ex-vivo experimental study included 19 DMEK-grafts treated with elastase, hyaluronidase, collagenase-IV, or collagenase-VIII at varying concentrations and temperatures. The maximal-scroll-width (MSW) served as a quantitative marker for scroll-tightness. Following enzymatic treatment, endothelial toxicity was evaluated by vital dye staining and endothelial cell shedding into the immersion buffer solution was quantified using a hemocytometer.Results Collagenase-IV (N = 6) at 1–2.5 mg/mL, 37°C for 30–45 min increased MSW by a mean of 22.1% (p < .05), whereas higher concentrations at room-temperature (RT) decreased MSW by 9.7% (p > .05). Collagenase-VIII (N = 2) showed no significant effects. Elastase (N = 7) at 1–2.5 mg/mL, RT for 90–120 min increased MSW by 6.7% (p < .05), while exposure at 37°C reduced MSW by 10.5% (p < .05). Hyaluronidase (N = 4) at 1–2.5 mg/mL, 37°C for 120 min decreased MSW by 19.2% (p < .01), whereas at RT, 1 mg/mL for 60 min increased MSW by 23% (p < .01). 29% of injured endothelial cells were observed across all the groups. Endothelial cell shedding was not significantly different between the two groups (p > .05).Conclusion Collagenase IV showed promising preliminary effects under selected experimental conditions; however, given the small subgroup sizes and variable findings, further controlled studies are required.