Qualitative Blade Topology in Donor Cornea Punches and Corresponding Endothelial Cell Loss in PK and DMEK Grafts

Abstract

Purpose: Two commonly used donor cornea punches were assessed using quantification of peripheral endothelial cell loss (ECL) and scanning electron microscopy (SEM) of blade topology and associated features on donor grafts. Methods: Penetrating keratoplasty (PK) (n = 8 pairs) and Descemet membrane endothelial keratoplasty (DMEK) (n = 8 pairs) grafts were prepared from mate donor corneas using Moria Busin or Corza Barron donor cornea punches (all punches were 7.5 mm) and analyzed for global and peripheral ECL. Punches were examined by SEM and subsequently used to prepare PK grafts from mate donor corneas (n = 3 pairs) that were also assessed by SEM. Results: For PK grafts, peripheral ECL caused by Busin and Barron punches was 4.2% ± 0.6% and 4.0% ± 0.9% (P = 0.62), respectively. For DMEK grafts, peripheral ECL caused by Busin and Barron punches was 3.6% ± 1.9% and 3.0% ± 1.3% (P = 0.48), respectively. SEM analysis of the Busin punch identified a rolled blade with a seam; the Barron punch is created from full rod stock and is seamless. Busin punch PK grafts have a ridge of stromal tissue that was not observed in the Barron PK grafts. Both punches exhibit anomalies along the blade edge, and the stroma of both grafts exhibited “drag lines.” Conclusions: Both punches caused similar and minimal ECL. In PK grafts, the seam of the Busin punch may be the source of the observed uneven stromal surface. Striations and debris on the cutting surfaces of both punches may produce drag lines in cut stroma. These topological features may contribute to uneven donor–recipient tissue apposition, leading to astigmatism after PK.