Endothelial Approach Ultrathin Corneal Grafts Prepared by Femtosecond Laser for Descemet Stripping Endothelial KeratoplastyCorneal Graft by Femtosecond Laser Inverse Cutting

METHODS. Thirty human corneoscleral buttons were cut from the endothelial side by laser Doppler velocimetry (LDV) with or without viscoelastic materials coating. Two cutting depths were selected: 70 and 90 lm. The postcut endothelial count was determined by specular microscopy, and the graft thickness was evaluated by anterior segment optical coherence tomography. The endothelial viability was determined using Trypan blue/Alizarin red staining, calcein-AM/EthD-1 live/dead cell assay, and scanning electron microscope (SEM). The graft interface smoothness was evaluated by SEM. Another 18 corneoscleral buttons were used as controls for the comparisons. RESULTS. The overall targeted cutting depth and achieved cutting depth were significantly highly correlated (r ¼ 0.84). The central to peripheral corneal thickness ratio was 0.976 and 0.998 for the 70- and 90-lm grafts. The percentage of the damaged endothelial cells assessed by vital staining and SEM showed the 70-lm grafts had noticeably more endothelial damage compared with the 90-lm grafts. But the damage was significantly reduced, to the control corneas level, after coating the endothelium with Viscoat. The 90-lm grafts had a slightly rougher graft interface than the 70-lm grafts, but all the grafts dissected by a Chansue dissector exhibited a generally smooth interface.