Endothelial cell density and corneal graft thickness following excimer laser vs. femtosecond laser-assisted penetrating keratoplasty-a prospective randomized study.

Purpose: The study aims to compare the impact of non-mechanical excimer laser-assisted (EXCIMER) and femtosecond laser-assisted (FEMTO) trephinations on graft endothelial cell density (ECD) and graft thickness before and after suture removal following penetrating keratoplasty (PK).

Methods: The inclusion criteria for this prospective, randomized, clinical study were as follows: (1) surgeries performed by one surgeon; (2) primary central PK; (3) keratoconus (KC) or Fuchs' dystrophy (FUCHS); (4) no previous intraocular surgery; (5) graft oversize, 0.1 mm; and (6) 16-bite double-running suture. In 68 eyes of 68 patients (mean age: 53.3 ± 19.8 years), PK was performed using either 193-nm MEL70 excimer laser ("EXCIMER": 17 KC, 18 FUCHS) or 60-KHz femtosecond laser ("FEMTO": 17 KC, 16 FUCHS) trephination. Specular microscopy (EM 3000) and pachymetry (EM 3000; Pentacam HR; Casia SS-1000) were performed before removing the first suture (11.4 ± 1.9 months) and after removing the second suture (22.6 ± 3.8 months), but before any additional ophthalmic surgery.

Results: ECD did not differ significantly (P ≥ 0.436) between EXCIMER and FEMTO either with "all-sutures-in" (1887 ± 409 vs. 1886 ± 438) or with "all-sutures-out" (1703 ± 379 vs. 1737 ± 362). Central corneal thickness and corneal thickness at the thinnest point of the cornea did not differ significantly between EXCIMER and FEMTO either with all-sutures-in (P ≥ 0.096 and P ≥ 0.653) or with all-sutures-out (P ≥ 0.636 and P ≥ 0.717).

Conclusions: EXCIMER and FEMTO trephinations from the epithelial side seem to have no disadvantages regarding endothelial cell loss after PK, and both surgical procedures are safe for the endothelium. A larger sample size and longer follow-up are needed to evaluate the long-term impact of EXCIMER and FEMTO trephinations on ECD.