Intraoperative 5-fluorouracil for filtration surgery in the rabbit

Postoperative subconjunctival injections of 5-fluorouracil (5-FU) improve the success rate of filtration surgery, but there is still a 20% or greater failure rate at 1 year in pseudophakic and repeat trabeculectomy cases. The injections are inconvenient to give and may produce corneal epithelial toxicity and other side effects. An alternative method for administration of 5-FU is investigated.

A masked, randomized, prospective study was undertaken to compare bleb survival and complications in a rabbit model, after either a single intraoperative exposure to 5-FU (50 mg/ml concentration for 5 minutes) or five postoperative injections of 5-FU (5 mg injection on postoperative days 1, 3, 5, 7, and 9), or a combination of both, with controls that received only a 5-minute exposure to distilled water, intraoperatively.

For the control eyes, all blebs were "flat" to masked grading, and intraocular pressure returned to preoperative levels by postoperative day 11. In the group receiving postoperative injections of 5-FU only, blebs were flat and the pressure normalized by postoperative day 14. Rabbits receiving intraoperative 5-FU only, or combined intraoperative 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 until postoperative day 21 (P < 0.05 for days 5 through 18). A combination of intraoperative and postoperative 5-FU produced significantly higher blebs than intraoperative 5-FU alone on days 7 to 14.

Intraoperative application of high-dose 5-FU to the filtration site either as a single 5-minute treatment, or in conjunction with postoperative injections of 5-FU greatly prolongs bleb function after filtration surgery in the rabbit.