Sub-Tenon injection of mitomycin C may have advantages over sponge application
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Sub-Tenon injection of mitomycin C may be an alternative to conventional application of MMC with sponges, according to a study.
The use of antimetabolites to prevent excessive postoperative scarring and reduce the risk for failure has become standard in glaucoma surgery. Since its first application in 1992, MMC has significantly improved the success rate of trabeculectomy. However, MMC has several potential toxicity-related side effects. Different concentrations and exposure times have therefore been tested to find the right balance between safety and efficacy.
In a prospective, randomized, single-center study, MMC administration by sub-Tenon injection was evaluated in comparison with the classic application of soaked sponges. Fifty-six eyes of 49 patients undergoing trabeculectomy for primary open-angle glaucoma were randomly assigned to MMC injection or sponge application. The injection group received 0.15 mL of the 0.1 mg/mL MMC solution administered in the sub-Tenon space with a 30-gauge needle at the beginning of surgery, after IV sedation and topical anesthesia. In the sponge group, six pieces of sponge presoaked in 0.2 mg/mL MMC solution were applied around and under the scleral flap for 2 minutes.
Comparable IOP reduction was achieved in the two groups, and complication rates were similar. Bleb morphological differences were reported in favor of the injection group at 1 year, in which blebs were lower, more diffuse and less vascularized.
“Injectable MMC during enhanced trabeculectomy has potential benefits over sponge application,” the authors wrote. These include less surgical time and elimination of the risk for retained sponge material, which may lead to tissue necrosis. In addition, injections deliver a specific measurable quantity of MMC to the surgical area.
This study demonstrated that sub-Tenon injection is similar in safety and efficacy to sponge application.
“Bleb morphologic features have notable differences that could favor a better long-term outcome in these cases, although studies with a larger sample size and longer follow-up are needed for confirmation,” the authors wrote.
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