MACROPHAGES DURING FIBROSIS FOLLOWING SCLERAL FISTULISING SURGERY IN A RAT MODEL

Purpose. Glaucoma filtration surgery can fail in a minority of patient s as a result of fibrosis in the subconjunctival bleb space and closur e of the scleral fistula. In this study, the rat eye has been used as an experimental model for fistulising surgery in order to evaluate the clinical manifetation of bleb failure with the morphological evtns of the wound healing process. Methods. A conjunctival bleb was successfu lly formed in 25 rats and was examined daily using slit lamp microscop y to evaluate postoperative inflammation and the presence of a bleb. A t defined post-operative time points, serial frozen sections of eyes w ere stained immunohistochemically using a panel of monoclonal antibodi es directed against known surface markers on rat immune/inflammatory c ells. Positively stained cells were counted (a) in the bleb site, (b) at the sclerostomy and (c) at the suture site. Results. Following an i nitial post-operative inflammation, a surgically formed sclerostomy an d conjunctival bleb underwent a granulation and scarring response so t hat by 7-19 days the bleb had disappeared. Using the monoclonal antibo dies applied in this study, it was possible to show that macrophages m ost likely play a major and pivotal role throughout the sequence of ev ents that lead to repair of the fistula and closure of the bleb. It wa s also noted that the presence of an otherwise inert nylon suture used to close the incised conjunctiva can serve as a focus for macrophages . Conclusion. The rat has been successfully used as an experimental mo del of fistulising surgery and its subsequent failure. The use of a pa nel of monoclonal antibodies directed against specific surface markers on immune-inflammatory cells, high-lighted macrophages to be prominen t in all stages of this wound healing process.