Choice of antifibrotic agent depends on risk of bleb failure

New York—Patients undergoing primary trabeculectomy who are at high risk for bleb failure should be treated with either a single application of mitomycin-C (MMC; Mutamycin, Bristol-Myers Oncology) or 5-fluorouracil (5-FU) intraoperatively followed by subconjunctival injection of 5-FU later, reported glaucoma specialist Celso Tello, MD.

"Although 5-FU and MMC increase the success of glaucoma filtering surgery by inhibiting fibroblast proliferation, MMC is more effective in preventing wound healing," explained Dr. Tello, assistant professor of ophthalmology, New York Medical College, New York Eye & Ear Infirmary, New York.

He explained the differences between the two antifibrotic agents during the glaucoma subspecialty day meeting at the American Academy of Ophthalmology annual meeting.

A single application Both antifibrotic agents can be used intraoperatively, applied with the use of large sponges. The 5-FU is applied for approximately 5 minutes while MMC is limited to a 1- to 3-minute application to avoid potential postoperative complications.

The 5-FU can also be delivered as a subconjunctival injection postoperatively, Dr. Tello said.

In a study at Moorfields Eye Hospital, London, researchers found that intraoperative 5-FU application was as effective as 5-FU subconjunctival injections in controlling fibroblast proliferation, he noted.

Safety and efficacy Two clinical trials have been conducted to evaluate the safety and efficacy of MMC and 5-FU in primary trabeculectomy. Singh and colleagues published a report in Ophthalmology in 2000, and WuDunn and colleagues published one in the American Journal of Ophthalmology in 2002. Both studies found that MMC and 5-FU were equally effective in IOP reduction for patients undergoing primary trabeculectomy. It was noted, however, that more complications were seen in patients treated with MMC, Dr. Tello said.

Complications seen with either antifibrotic agent include late-onset bleb leaks, bleb-related endophthalmitis, and hypotony maculopathy secondary to overfiltration.

"But these complications are more commonly seen with MMC," he said.

Recommendations For patients who are at low risk for bleb failure, Dr. Tello recommends 5-FU (50 mg/ml) given as a single intraoperative application over a wide area of exposure for 5 minutes. For those patients at high risk for bleb failure, he suggests MMC (0.2 to 0.4 mg/ml) administered as a single application over a wide area of exposure for 1 to 3 minutes. He also said that 5-FU can be used as described above and then followed later by a supplemental subconjunctival injection of 5-FU as needed for high-risk cases.

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