CORNEAL NERVE DAMAGE AND REGENERATION AFTER EXCIMER-LASER PHOTOKERATECTOMY IN RABBIT EYES

Purpose. To investigate corneal nerve damage and its subsequent regene ration after excimer laser photokeratectomy in rabbit eyes. Methods. C orneal photokeratectomy was performed on the right eyes of 34 pigmente d rabbits, while the left eyes were used as a control. A Summit W 200 excimer laser (Summit Technology, Waltham, MA) was used to produce a 1 00 mu m depth phototherapeutic keratectomy (4.5 mm diameter). The rabb its were killed at 0, 1, 2, 3, 4, 5, 7, 8, 10, 15, and 20 days and 1, 2, 3, and 4 months after treatment. Corneal nerve regeneration was inv estigated using a monoclonal antibody directed against a 150 kD subuni t of neurofilaments, in combination with acetylcholinesterase staining . Results. At time 0, the subepithelial plexus had disappeared complet ely from the photoablated area. One day after treatment, some regenera ting nerves sprouting within the treated area were visualized by a mon oclonal antibody directed against a 150 kD subunit of neurofilaments. Acetylcholinesterase staining was detectable 7 days later. One month a fter surgery the subepithelial plexus had already reappeared, but was morphologically disorganized. Four months after treatment, the newly f ormed subepithelial plexus had considerably thickened in comparison wi th that of the control eye. Conclusions. This study shows that corneal nerve regeneration after excimer laser photoablation in rabbit eyes, although more intense, is similar to that produced after other surgica l procedures involving the epithelium and the anterior stroma or one o f the two.