Wound healing following anterior keratectomy and lamellar keratoplasty in the pig

PURPOSE: To examine corneal wound healing in an animal model of two types o f mechanical lamellar keratectomy. METHODS: One eye from each of 28 pigs was studied. Using a motorized kerato me, corneas were subjected to an anterior lamellar keratectomy with removal of anterior stroma and epithelium, or to automated lamellar keratoplasty ( ALK) with reapposition of a corneal flap. The exposed stromal surfaces were labeled intraoperatively with a fluorescent dye (DTAF) to assess depositio n of stromal components during subsequent wound healing Examination before surgery and enucleation included measurement of corneal curvature and intra ocular pressure, and assessment of corneal haze. Eyes were prepared for his tological examination, fluorescence microscopy, and for fibronectin immunoh istochemistry. RESULTS: Both keratectomy procedures produced Battening of corneas by up to 3.80 diopters, 28 days after surgery. Corneal haze was more pronounced in eyes from which epithelium was removed (anterior lamellar keratectomy group ). The increased haze in this group was associated histologically with appe arance of many reactive keratocytes and inflammaotory cells, deposition of new stromal material, and more widespread appearance of fibronectin immunor eactivity, In the lamellar keratoplasty group, only the edges of the cornea l wound showed significant reactivity, and included keratocyte activation a nd epithelial ingrowth. CONCLUSIONS: The pig provides a useful model for studies of refractive surg ical techniques using procedures and instruments designed for use in humans . Mechanized keratectomy procedures that. minimize disruption of the epithe lium and Bowman's layer produce a less reactive corneal wound than procedur es in which an expanse of epithelium and anterior stroma are removed.