Background: In our previous study, both allogeneic and xenogeneic smallincision femtosecond laser-assisted intrastromal keratoplasty were demonstrated to be safe and effective surgeries. Glycerol-dehydrated corneal lamellae could serve as alternative xenogeneic inlay grafts. However, these xenogeneic lamellae have not been explored in lamellar keratoplasty (LK). The immunoreactivity differences between corneal intrastromal xenotransplantation and xenogeneic LK have not been assessed.
Methods: Rabbit lamellae were formed by femtosecond laser-assisted surgeries and dehydrated in glycerol for 1 week at 4°C. The lamellae were used in two surgical approaches in the small incision lenticule extraction (SMILE) group and the LK group. Postoperatively, slit-lamp examinations, corneal topography, anterior segment optical coherence tomography (AS-OCT), in vivo confocal microscopy and tear inflammatory mediator assays were performed.
Results: Throughout the 12-month observation period, all rejection index ratings were higher in the LK group than in the SMILE group. No signs of graft rejection were observed in the SMILE group, but obvious neovascularization and corneal rejection occurred in the LK group. Corneal topography showed that the anterior curvatures at the central cornea and the mid-peripheral cornea were significantly increased in the SMILE group but decreased in the LK group. All the grafts from both groups were clearly visible on AS-OCT. In vivo confocal microscopy showed few dendritic cells in the subepithelial region in the SMILE group. Numerous dendritic cells and inflammatory cells were observed in the basal epithelium and stroma in the LK group. In the LK group, the levels of TGF-β1, CD40, ICAM-1, CD14 and IL-10 changed more than those in the SMILE group. The levels of VEGF were significantly elevated 1 month after surgery in the LK group.
Conclusion: Small-incision femtosecond laser-assisted intrastromal keratoplasty minimized invasiveness and improved surgical efficiency. This small-incision intrastromal keratoplasty technique is superior to LK in terms of xenogeneic lamellae biocompatibility. Moreover, glycerol-dehydrated corneal lamellae might be a viable xenogenic corneal inlay graft.