Surgeons develop their own regimens to use antimetabolites in more cases

They are seeking to improve filtering surgery outcomes while controlling side effects.

CHICAGO — The use of antimetabolites has changed as surgeons develop their own regimens to improve filtration surgery outcomes, according to Jacob T. Wilensky, MD, a professor of ophthalmology here at the University of Illinois at Chicago.

“Virtually everyone I know now routinely uses antimetabolites on high-risk cases, and there are many people who use antimetabolites routinely on virtually all of their filtering surgery,” Dr. Wilensky said.

Finding the right dose has become an individual choice for surgeons.

Work conducted in the early 1980s applied the work of retinal surgeons trying to prevent vitreous proliferation. In 1985, the U.S. National Institutes of Health conducted a study of 5-FU and found it an effective adjunct in high-risk cases, he said.

Contradictory data

Since then, groups of surgeons across the nation have conducted their own research and reported results in the scientific literature. Comparisons of published studies are difficult because the various reports used different dosages and applied them in different ways.

“There is a lot of data, it’s very contradictory, and so you still have to pick and choose what you feel comfortable with,” he said.

Also the recent literature has had increasing reports of late complications following the use of antimetabolites such as bleb leaks, endophthalmitis and hypotony maculopathy. These complications have caused some surgeons to reassess their use of antimetabolites.

Less drug, less toxicity

The protocol for using 5-FU has changed from twice-per-day injections for the first week and once-per-day for the second week to three to seven or eight injections over a 2-week period or less, or a single application. Intraoperatively, during which the surgeons apply the drug for a few seconds or up to five minutes.

With so many variables reported in the literature, Dr. Wilensky said he has developed his own regimen for applying antimetabolites.

When he uses 5-FU, he applies it topically with a sponge for 5 minutes in the operating room using the full 50 mg/cc concentration. He said he uses 5-FU on the majority of his primary filters topically at the time of surgery. Occasionally, he will supplement the intraoperative 5-FU with postoperative subconjunctival injection of 5 mg during the postoperative period.

He switches to mitomycin for combined procedures, neovascular or uveitic eyes, and aphakic and pseudophakic patients.

“I almost very rarely use added 5-FU postoperatively,” he said. “I can count on two hands the number of times I’ve used it after mitomycin.”

Adjusting the regimen

He places the sponge with the antimetabolite on the scleral surface and not under the scleral flap because he believes that filters fail because of proliferation of Tenon’s capsule and not due to scarring of the scleral flap.

“You can just lift up the flap, and the flap is not the problem, it’s on the surface,” he said. “That’s why I have used the antimetabolites on the surface. I usually do it before I dissect the flap just because I think it’s easier.”

For Your Information:

Jacob T. Wilensky, MD, can be reached at 1855 W. Taylor, Chicago, IL 60612 U.S.A.; +(1) 312-996-7030; fax: +(1) 312-996-7770.