The Comparison of Femtosecond Laser-Assisted Penetrating Keratoplasty With Conventional Surgery in Terms of Endothelial Safety: Ex Vivo Study Using Porcine Eyes

Abstract

To evaluate the effect of using femtosecond (FS) laser technology for penetrating keratoplasty (PK) in terms of corneal graft endothelial ultrastructure and viability in porcine eyes. Thirty-two freshly enucleated porcine eyes were divided into 4 equal groups (n = 8): group 1, incomplete penetration using the FS laser (a 100 microm-depth from the endothelial side remained); group 2, complete penetration using the FS; group 3, trephination using a vacuum trephine until the aqueous humor appeared; group 4, no treatment (control group). For groups 1 and 2, side cuts were performed using a 60-kHz FS laser (IntraLase FS Laser, Abbot Medical Optics, Abbott Park, IL). Preoperative ultrasound pachymetry was used to make measurements at 5 positions. Scanning electron microscopy (SEM) was used to determine morphological changes, and light microscopy with Alizarin red staining was used to determine the amount of cell death. Preoperative corneal thicknesses were similar for all groups. All 4 groups showed similar corneal endothelial cell morphology and viability at the graft center (P = 0.15, Kruskal-Wallis test). At the graft border, endothelial cell damage was minor in group 1, moderate in group 2, and most severe and diffuse in group 3 (P = 0.009, Kruskal-Wallis test). FS laser use is safe for the endothelium at the graft center and has less harmful effects on the endothelium at the incision area than does conventional trephination. Therefore, FS laser-assisted corneal grafts with complete penetration seems to be the optimum choice for preserving endothelial cells during PK.