Comparison of stromal remodeling and keratocyte response after corneal incision and photorefractive keratectomy]

PURPOSE: We investigated the keratocyte response and stromal remodeling after corneal incision and photorefractive keratectomy, respectively to learn the difference between the two surgeries histophysiologically and immunohistochemically. METHODS: We performed corneal incision or photorefractive keratectomy in rabbits or rats, and then we chronologically observed the histological changes and the changes in localization of extracellular matrix proteins. RESULTS: In both types of surgery, the keratocyte population in the damaged stroma became sparse, and the cells were undergoing apoptosis immediately after the procedures. After that, activated keratocytes migrated into the acellular zone, and the cells formed multiple layers at the resurfaced subepithelial regions. Deposition of amorphous substances was observed between migrated keratocytes, and stromal remodeling began. Three months after the surgery, corneal structure had recovered to near normal condition in the corneal incisions. In photorefractive keratectomy, however, strong immunoreactivity of extracellular matrix proteins was observed in the subepithelial regions. CONCLUSIONS: These results suggested that stromal wound healing processes were similar in both corneal incision and photorefractive keratectomy. Corneal incision may induce transient keratocyte response during the stromal remodeling, but photorefractive keratectomy may induce sustained keratocyte response.