REAL-TIME CONFOCAL MICROSCOPY OF KERATOCYTE ACTIVITY IN WOUND-HEALINGAFTER CRYOABLATION IN RABBIT CORNEAS

A modified tandem scanning confocal microscope was used for real-time in vivo examination of the rabbit cornea following a cryogenic injury. The corneas of New Zealand white rabbits were frozen with a probe tha t had been cooled by immersion in liquid nitrogen, effectively destroy ing keratocytes in a central 5 mm diameter zone throughout the total t hickness of the cornea. In these eyes, keratocyte repopulation and cor neal stromal wound healing proceeded similarly to that which occurs af ter epikeratophakia, a refractive surgical procedure designed to chang e the curvature and optical power of the cornea. In epikeratophakia, a cryolathed donor corneal stroma lenticule is sutured on to the bare s troma of the recipient cornea. The collagen tissue lenticule is repopu lated by keratocytes (corneal fibroblasts) that migrate in from the ho st cornea. In our study, the confocal microscope permitted sequential, noninvasive examination of the corneal stroma in the treated animals. Necrosis of the keratocytes, followed by activation of the remaining viable cells in the corneal periphery, was observed in the first 2 to 3 days after cryo injury. A fine stromal fibrous network was seen to d evelop; in three eyes, this network progressed to the development of a retrocorneal fibrous membrane and dense stromal fibrosis, both of whi ch resulted in significant loss of corneal clarity. Our results sugges t that the confocal microscope may be a valuable tool to provide much needed information on wound healing processes at the cellular level af ter corneal surgery and injury.