Feline Corneal Stroma Is Endowed With Unique Regeneration Properties

Abstract

Abstract: : Purpose: To demonstrate corneal stroma thickness regeneration and reinnervation in 3 cats that underwent lamellar keratectomy during supradescemetic (∼99% depth) keratoprosthetic implantation. Methods: Three 2 y/o female adult cats that underwent spontaneous keratoprosthesis extrusion approx. 85 days (ranging from 15 to 150 days) after implanting a supra–Descemetic prosthesis into their right eye were studied. Corneal stroma thickness was evaluated by slit lamp photographs, pachymetry and real time confocal microscopy. Regenerated corneal stroma matrix and keratocytes and epithelial cells were studied with transmission electron microscopy and histological sections. Immunocharacterization was performed with antibodies against 68 kDa neurofilament that stained corneal nerves, monoclonal K3 antibodies that detects corneal epithelium and α– smooth muscle actin to identify myofibroblasts. Results: Corneas increased in thickness progressively and acquired a normal thickness and appearance within 40 – 60 days after KPro extrusion. Slit lamp photographs demonstrated a continuous increase in stromal thickness and transparency. Pachymetry demonstrated a continuous increase in corneal thickness until reaching 600 µm or more in all eyes. In vivo confocal microscopy showed the restoration of a normal epithelium, stroma and endothelium in all cats. Corneal nerves were seen in the stroma of 2 cats. In one cat, stromal and endothelial visualization were impaired by corneal haze. Electron microscopy showed regeneration of a normal epithelium with well formed basement membranes, organized corneal lamellae and the presence of normal appearance keratocytes. Immunostaining demonstrated the presence of immunoreactive neurofilament expressing nerves suggesting restoration of corneal reinnervation. Scarce myofibroblasts were observed in the regenerated stroma. Corneal stratified epithelium appeared normal and expressed K3 keratin. Conclusions: Feline are capable of regenerating corneal stroma matrix formation and reinnervation after deep lamellar keratectomy. The use of feline models in keratoprosthesis evaluation is questioned. Support: Florida Lions Eye Bank; NIH center grant P30–EY014801, Corneal SA, Paris France, Research to Prevent Blindness; Henri and Flore Lesieur Foundation.

Keywords: keratoprostheses • cornea: stroma and keratocytes • wound healing