5-FU recommended for primary trabeculectomy

Intraoperative 5-fluorouracil treatment results in fewer focal blebs, less leakage and reduced infection in primary trabeculectomies, according to one surgeon.

Issue: February 1, 2005

ByKim Norton

One 50-mg/mL intraoperative application of 5-fluorouracil for 5 minutes can successfully treat a large exposure area of a primary trabeculectomy with few complications in low-risk glaucoma patients. For high-risk patients, an intraoperative application of 5-fluorouracil with an additional postoperative injection is also effective, according to Celso Tello, MD.

In place of the 5-fluorouracil (5-FU) treatments in high-risk glaucoma patients, a single intraoperative application of mitomycin-C can be equally effective, according to Dr. Tello. However, the complication rate of mitomycin-C is higher than that of 5-FU, Dr. Tello said in his presentation at the American Academy of Ophthalmology meeting in New Orleans.

“A single intraoperative application of 5-FU can mean fewer focal blebs, which means less leakage and a reduced probability of infection in low-risk glaucoma patients undergoing a primary trabeculectomy,” Dr. Tello said.

5-FU

A postoperative injection of 5-FU increases the likelihood of a successful filtration surgery outcome, according to the clinical research presented by Dr. Tello. He found that in high-risk patients an intraoperative application of 5-FU followed by a postop injection could be successful in lowering IOP and ensuring the viability of the bleb.

“A single intraoperative injection of 5-FU may be sufficient in controlling IOP in the short term, but in high-risk patients, a single application of 5-FU may not be enough to ensure bleb survival,” Dr. Tello said. He noted that supplemental postoperative injections may be required.

Despite the effectiveness of 5-FU in trabeculectomy patients, there are risks associated with its use, mainly corneal toxicity, conjunctival wound leak and late endophthalmitis related to thin avascular blebs, he said.

In clinical manifestations, punctate and filamentary keratopathy were observed. Other complications included a large epithelium defect, a whorl-like or striate melanokeratosis, corneal changes that may predispose patients to bacterial corneal ulceration, corneal melting and corneal perforation. The use of topical steroids to reduce postop inflammation may predispose the patient to corneal toxicity, Dr. Tello added.

To avoid toxicity, 5-FU injections should be administered based on the patient’s response to the drug rather than administering a fixed protocol, he said.

In a prospective randomized clinical trial of mitomycin-C vs. 5-FU, both had similar IOP-lowering effects but complications occurred more often in the mitomycin-C group, according to Dr. Tello.

Mitomycin-C

In high-risk patients, mitomycin-C can be more effective in a single application than 5-FU in multiple doses, Dr. Tello said. Unlike 5-FU, which can be applied intraoperatively and as a postop injection, mitomycin-C can only be used during surgery to control endothelial cell growth and replication, he said. The toxicity of mitomycin-C will not allow it to be used in postoperative treatment, he added.

Mitomycin-C is more potent than 5-FU. Blebs treated with mitomycin-C are usually thinner and more vascular, Dr. Tello said. Prolonged exposure of mitomycin-C makes it a more suitable single-use adjunct in high-risk glaucoma filtering patients, according to his research.

Complications with mitomycin-C are similar to those of 5-FU, but the complications tend to be more severe, he said. Late-onset bleb leaks are three times more likely to occur in patients treated with mitomycin-C vs. those treated with 5-FU, Dr. Tello said. Hypotony maculopathy secondary to overfiltration is also a complication of mitomycin-C, he said.

For Your Information:
Celso Tello, MD, can be reached at 310 E. 14th St., New York, NY 10003; 212-477-7540; fax: 212-420-0067; e-mail: ctello@nyee.edu.
Kim Norton is an OSN Staff Writer who covers all aspects of ophthalmology.