Manually prepared lamellae for Descemet stripping endothelial keratoplasty (Pachy-DSEK): comparison of four dissection depths.

Abstract

This study aimed to compare four depths of manual dissection for the preparation of Descemet stripping endothelial keratoplasty lamellae. Eye bank corneas were randomized into four groups according to dissection depths: Pachy-100 (incision depth = central corneal thickness-safety margin of 100 µm), Pachy-50 (safety margin of 50 µm), Pachy-0 (no safety margin), and Pachy+50 (incision depth = central corneal thickness + 50 µm). All endothelial lamellae were prepared using a standardized method of manual dissection (Pachy-DSEK). The central, paracentral (3.0-mm zone), and peripheral (6.0-mm zone) lamella thicknesses and incision depths were measured by optical coherence tomography. The 3.0-mm and 6.0-mm zone central-to-peripheral thickness ratios were calculated. Endothelial perforation occurred only in the Pachy+50 group (n=3, 30%). Central lamella's thickness in Pachy-100, Pachy-50, Pachy-0, and Pachy+50 groups measured 185 ± 42 µm, 122 ± 29 µm, 114 ± 29 µm, and 58 ± 31 µm, respectively (p<0.001). The overall 3.0- and 6.0-mm C/P ratios were 0.97 ± 0.06 and 0.92 ± 0.14, respectively. Preoperative donor characteristics were not correlated with most thickness outcomes. The planned incision depth correlated significantly with most lamella's thickness parameters (p<0.001). The overall thickness of the lamella negatively correlated with the planned incision depth (p<0.001, r=-0.580). The best outcome was found in the Pachy-0 group, as 75% of the lamellae measured <130 µm and there was no endothelial perforation. By using a standardized method of dissection, most manually prepared lamellae presented a planar shape. Setting the incision depth to the central corneal thickness did not result in endothelial perforation and a high percentage of ultrathin lamellae was achieved.