Quantifying Corneal Endothelial Cell Damage During Descemet Membrane Endothelial Keratoplasty Graft Loading and Ejection Using a Calcein-AM Imaging Method.

Purpose: (1) To compare total endothelial cell damage from loading and ejection of Descemet membrane endothelial keratoplasty (DMEK) grafts through Straiko and Lions World Vision Institute (LWVI) glass cannulas. (2) To isolate and quantify endothelial cell damage from loading or ejection alone in Straiko tubes.

Methods: DMEK grafts were peeled, stained with Calcein-AM (CAM), and imaged under fluorescence microscopy to evaluate baseline endothelial damage. Grafts were then loaded and ejected from Straiko and LWVI glass cannulas, and reimaged. Loss of CAM fluorescence signal was evaluated to calculate change in Area of Cell Damage (ACD). ACD changes were compared between Straiko and LWVI cannulas. Custom-made Straiko "half-tubes," consisting of only the loading or ejection end of a Straiko tube, were used to isolate graft loading from ejection, and CAM-based ACD was again assessed.

Results: Loading and ejection resulted in a significant increase in ACD for both Straiko (4.88% ± 0.53%) and LWVI (4.22% ± 0.57%) cannulas, but this was not statistically different between cannulas (P = 0.42). For Straiko half-tubes, ejection alone (3.08% ± 0.31%) resulted in a significantly greater increase in ACD compared with loading alone (1.38% ± 0.36%) (P = 0.004).

Conclusions: Ejection of DMEK grafts through a Straiko tube causes more endothelial cell damage than loading. Loading and ejection of DMEK grafts through Straiko and LWVI tubes were associated with similar endothelial cell damage. Bore size alone cannot explain these results. The overall damage, measured using CAM, was lower than previously reported studies that relied on different methods for quantifying damage.