Non-white Ethnicity, Lower Dose of Mitomycin C Associated with Increased Surgical Failure in MIBS

Minimally invasive bleb surgeries (MIBS), including Xen Gel Stent (Allergan Inc.) and PreserFlo MicroShunt (Santen Pharmaceutical Co.), have garnered attention in recent years due to their enhanced safety profile and faster visual recovery compared to conventional bleb-forming glaucoma filtration surgeries such as trabeculectomy. However, the long-term effectiveness of these procedures in lowering intraocular pressure (IOP) remains uncertain, and there is still ambiguity concerning the risk factors that influence surgical success. To help improve patient selection, a recent systematic review published in American Journal of Ophthalmology analyzed the demographic and ophthalmic variables associated with surgical failure in observational studies of MIBS. A systematic review found that patients who undergo minimally invasive bleb surgery (e.g., Xen Gel Stent and Preserflo MicroShunt) are more likely to experience surgical failure if they have a higher baseline IOP, are on multiple glaucoma meds prior to surgery or have greater visual impairment at baseline. Higher risk was also noted among patients of Asian or non-Hispanic Black ethnicity and those who received lower doses of mitomycin C (<0.4mg/mL) during surgery. Photo: Allergan/Glaukos. Click image to enlarge.The authors reviewed 395 articles from various databases, ultimately narrowing their selection to 18 studies that encompassed 19 cohorts. In total, data from 9,580 eyes of 9,281 subjects were analyzed. Some studies defined surgical success strictly in terms of IOP thresholds, while others combined percentage reductions and the absence of additional glaucoma surgeries (excluding needling) to characterize successful outcomes.The results highlighted significant associations between specific preoperative and demographic factors and surgical failure rates. Notably, non-white ethnicities, particularly Asian and non-Hispanic Black patients, were shown to have a higher risk of surgical failure, with hazard ratios ranging from 1.52 to 4.9. The study also examined the influence of mitomycin C usage during surgery, finding that lower doses (<0.4mg/mL) correlated with increased failure rates compared to higher doses (0.4 to 0.5mg/mL). Ophthalmic factors associated with a higher risk of surgical failure included baseline IOP, baseline medication use and baseline visual field mean deviation. Glaucoma subtypes were also shown to significantly impact outcomes; namely, patients with pseudoexfoliative/pigmentary, angle-closure, uveitic and normal-tension glaucoma presented higher risks of surgical failure. In contrast, greater surgical success rates were observed among ocular hypertension/open-angle suspects and patients with non-primary open-angle or secondary open-angle glaucoma. However, the researchers note that these findings were markedly heterogeneous with a very low certainty of evidence and should be interpreted with caution.“The conflicting associations between secondary glaucoma diagnosis and surgical failure may arise from the heterogeneity of this group of conditions,” they explained in their paper. The authors continued, “The distribution of secondary glaucoma subtypes appears to influence reported surgical outcomes, as glaucoma secondary to medication, trauma or inflammation has been shown to reduce the risk of failure for MIBS.” Considering the high cost of MIBS devices, continued research is necessary to delineate risk factors for surgical failure and guide patient selection, the study authors concluded.Click here for the journal source. Jung M, Kong YZ, Ansari AS, Lawlor M, Tan JCK. Risk factors for failure in minimally invasive bleb surgery: a systematic review. Am J Ophthalmol. December 2, 2025. [Epub ahead of print]. This article was developed by the editorial staff in conjunction with experts in the field. In the process, AI may have been among the editorial tools used to meet the goals of human editors, who approved all content.