Antifibrotic Agents in Trabeculectomy
The increased use of mitomycin C and 5-fluorouracil has improved the rate of surgical success, especially in patients with risk factors for failure. Use of these antifibrotic agents has also led to higher rates of bleb leak, infection, and hypotony; but the increase is related to the longer survival of the trabeculectomy attained with these agents. Antifibrotic agents can be applied subconjunctivally by means of soaked sponges or injection.
5-Fluorouracil (5-FU) is a pyrimidine analogue that inhibits DNA synthesis through its action on thymidylate synthetase and thereby interferes with fibroblast proliferation. This agent can be used both intraoperatively (soaked on sponges) and postoperatively (injected subconjunctivally) to increase the success rate of trabeculectomy. 5-FU can be highly toxic to the corneal epithelium and thus should be used with caution in patients with ocular surface disease.
Mitomycin C (MMC) is a naturally occurring compound with antineoplastic and antibiotic activities. MMC is an alkylating agent that crosslinks DNA, thus inhibiting DNA replication and inducing apoptosis. It is cytotoxic to fibroblasts and vascular endothelial cells, thereby modulating the fibroproliferative and angiogenic steps of wound healing. It is administered by application of soaked sponges or subconjunctival injection. Both techniques lead to similar IOP outcomes, although injection may promote the formation of more diffuse blebs (Figs 13-10, 13-11). MMC is highly toxic, and intracameral exposure should be avoided.
A Cochrane review of the literature found that IOP was significantly lower with adjunctive MMC compared with 5-FU 1 year after trabeculectomy. Visual outcomes were similar between the groups.
Cabourne E, Clarke JC, Schlottmann PG, Evans JR. Mitomycin C versus 5-fluorouracil for wound healing in glaucoma surgery. Cochrane Database Syst Rev. 2015;11:CD006259. Epub 2015 Nov 6.
Esfandiari H, Pakravan M, Yazdani S, et al. Treatment outcomes of mitomycin C-augmented trabeculectomy, sub-Tenon injection versus soaked sponges, after 3 years of follow-up. Ophthalmol Glaucoma. 2018;1(1):66–74.
Palanca-Capistrano AM, Hall J, Cantor LB, Morgan L, Hoop J, WuDunn D. Long-term outcomes of intraoperative 5-fluorouracil versus intraoperative mitomycin C in primary trabeculectomy surgery. Ophthalmology. 2009;116(2):185–190.
Figure 13-10 Clinical photograph shows a diffuse conjunctival bleb. Although it is difficult to see the bleb, the clues are the irregular conjunctival border at the limbus and scarring at the 10- and 2-o’clock positions, where sutures were placed during surgery. With careful slit-lamp examination, one will notice that the bleb is elevated off the sclera.
(Courtesy of JoAnn A. Giaconi, MD.)
Figure 13-11 Clinical photograph of a localized conjunctival bleb.
(Courtesy of Jody Piltz-Seymour, MD.)
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.