Influence of Graft Unfolding Time During Descemet Membrane Endothelial Keratoplasty on Postoperative Endothelial Cell Loss and Visual Acuity.

Descemet membrane endothelial keratoplasty (DMEK) is currently the gold standard for Fuchs endothelial corneal dystrophy (FECD). The steps of graft insertion, unfolding, and attachment are known to be challenging. The aim of the study was to explore the influence of graft unfolding time on postoperative visual outcomes and endothelial cell loss (ECL). In this retrospective single center case series, 117 eyes of 90 patients with FECD were included. Endothelial cell density (ECD) and best-corrected visual acuity (BCVA) were measured preoperatively, 3 months and 1 year after DMEK, and we recorded graft unfolding time during DMEK. To assess the correlation between the outcome parameters and the graft unfolding time, Spearman correlation was performed. Mean ECD of the grafts was 2574.5 (±196.0) cells/mm2 preoperatively and 1642.1 (±531.1)/1585.6 (±478.5) cells/per mm2 at 3 months/1 year postoperatively, respectively, which led to an average ECL of 36.3/38.6%. BCVA preoperatively was 0.40 (±0.26) logMAR, which improved to mean postoperative BCVA of 0.16 (±0.10)/0.13 (±0.09) logMAR 3 months/1 year after DMEK, respectively. The mean graft unfolding time was 03:06 (±02:17) minutes. A significant higher endothelial cell loss at 3 months was found among patients whose graft unfolding time took ≥5 minutes. However, no significant correlations between graft unfolding time and BCVA, ECL, or rebubbling rate were shown. Our analysis showed that the BCVA is not affected by the graft unfolding time, but suggests that prolonged graft unfolding time may have a clinically relevant impact on postoperative ECL. Therefore, it may affect graft survival in the long term.