Efficacy and Safety of the Subtenon Injection of 0.01% Mitomycin C-augmented Trabeculectomy

Background Trabeculectomy, with the application of mitomycin C (MMC), has been the gold standard glaucoma-filtering surgery. The conventional method of applying MMC using soaked sponges does not ensure a controlled amount of delivery of MMC, and incidences of blebitis are reported to be associated with leftover sponges. This study aims to assess the safety and efficacy of a low dose (0.1 mg/ml) of MMC administered through subtenon injection during trabeculectomy combined with cataract extraction, addressing existing research gaps. Methods It is a prospective interventional study on patients who underwent trabeculectomy with a subtenon injection of 0.1 mg/ml of MMC combined with cataract extraction and were followed up over six months. Efficacy was determined in terms of intraocular pressure (IOP) reduction; bleb architecture was graded using the Indiana Bleb Appearance Grading System (IBAGS) and success rate, and safety was commented upon in terms of complications. Results Thirty patients were enrolled, with the majority having primary open-angle glaucoma (63.33%), while 36.67% had primary angle-closure glaucoma. Baseline IOP was 31.40(±10.38) mmHg. It significantly reduced to 14.60(±3.75) mmHg on the first postoperative day, decreasing to 9.55(±1.57) mmHg by the sixth postoperative month (p=0.001). The percentage reduction in IOP was substantial, 69.57%, by the sixth postoperative visit. Bleb morphology assessment using IBAGS revealed significant improvements in bleb height and extent and a reduction in vascularity over the six-month follow-up (p=0.001), and no eyes had bleb encapsulation. Out of the total patients, 93.33% achieved controlled IOP without anti-glaucoma medications, while 6.67% required one medication for IOP control. Complications were minimal, with transient corneal edema in six patients and manageable postoperative hypotony in one case. Conclusion A subtenon injection of MMC during trabeculectomy effectively reduces IOP and promotes favorable bleb architecture, offering an effective and safer alternative to the conventional approach.