INTRAOPERATIVE 5-FLUOROURACIL FOR FILTRATION SURGERY IN THE RABBIT

Purpose. Postoperative subconjunctival injections of 5-fluorouracil (5 -FU) improve the success rate of filtration surgery, but there is stil l a 20% or greater failure rate at 1 year in pseudophakic and repeat t rabeculectomy cases. The injections are inconvenient to give and may p roduce corneal epithelial toxicity and other side effects. An alternat ive method for administration of 5-FU is investigated. Methods. A mask ed, randomized, prospective study was undertaken to compare bleb survi val and complications in a rabbit model, after either a single intraop erative exposure to 5-FU (50 mg/ml concentration for 5 minutes) or fiv e postoperative injections of 5-FU (5 mg injection on postoperative da ys 1, 3, 5, 7, and 9), or a combination of both, with controls that re ceived only a 5-minute exposure to distilled water, intraoperatively. Results. For the control eyes, all blebs were ''flat'' to masked gradi ng, and intraocular pressure returned to preoperative levels by postop erative day 11. In the group receiving postoperative injections of 5-F U only, blebs were flat and the pressure normalized by postoperative d ay 14. Rabbits receiving intraoperative 5-FU only, or combined intraop erative and postoperative 5-FU, had consistently higher blebs than the former two groups, and some blebs survived until postoperative day 25 . The mean intraocular pressure remained depressed in these groups unt il postoperative day 21 (P < 0.05 for days 5 through 18). A combinatio n of intraoperative and postoperative 5-FU produced significantly high er blebs than intraoperative 5-FU alone on days 7 to 14. Conclusions. Intraoperative application of high-dose 5-FU to the filtration site ei ther as a single 5-minute treatment, or in conjunction with postoperat ive injections of 5-FU greatly prolongs bleb function after filtration surgery in the rabbit.