Trabeculectomy has been performed since the mid-1960s and remains the gold standard for glaucoma surgery. Newer surgical options have evolved, collectively referred to as minimally invasive glaucoma surgeries (MIGS). Despite producing large intraocular pressure decreases, full-thickness procedures into the subconjunctival space may be limited by fibrosis. Application of 5-fluorouracil and mitomycin-C (MMC) have been in use with trabeculectomy with good evidence of significantly increased success, at the cost, however of an increased risk of complications. Off-label MMC application can be found in almost all clinical trials, including in combination with MIGS. We explore current evidence for MMC use in trabeculectomy, how this may differ for MIGS devices, and analyze the range of agents and doses that are used. Although we found that most studies could not show any correlation between MMC dosage and the surgical outcome, the success rates with the Xen microshunt seemed to be higher when using 20 mcg of MMC than when using 10 mcg. Certain important methodological considerations make this hard to confirm definitively, and other factors such as placement of the device may play a more substantial role. For the PreserFlo microshunt, preliminary data suggests higher success rates with higher MMC dosage at the cost of higher device-related adverse events and reoperations. Although the ideal dose still needs to be established, it seems very likely that MMC provides significant improvement in outcomes in bleb-forming MIGS procedures.Copyright © 2020. Published by Elsevier Inc.