Purpose <p>To evaluate the safety and efficacy of trabeculectomy, modified with a subscleral polytetrafluoroethylene (Teflon) tube for posterior aqueous diversion, in eyes with refractory glaucoma.</p> Methods <p>In this prospective pilot study, 43 eyes with refractory glaucoma underwent fornix-based trabeculectomy with placement of a 26 G IV cannula (tube), within a subscleral tunnel designed to create a posterior outflow pathway. Success was defined as an IOP of ≥6 mmHg and ≤18 mmHg, with at least 30% reduction from preoperative treated values and was deemed absolute success if no anti glaucoma medications were needed to achieve this target, and qualified if medications were needed. Outcomes analysed included IOP, number of antiglaucoma medications, bleb morphology, anterior segment OCT, and complications over 12 months.</p> Results <p>Data of thirty eyes with a complete 12-month follow-up was analysed. Mean preoperative IOP was 41.4 ± 9 mmHg on 4.1 ± 0.8 medications. At 12 months, mean IOP decreased to 14.6 ± 2.9 mmHg (<i>p</i> &lt; 0.001) with 1 ± 1 medication. The overall success was 97%, with the absolute and qualified success being 43% and 54%, respectively. Early hypotony occurred in 77% of eyes, resolving spontaneously within 2 weeks. Posteriorly elevated or diffuse blebs developed in 10 eyes, anterior blebs in 5 eyes, 8 eyes had blebs localised around the posterior tube opening, while flat blebs with subscleral fluid reservoirs developed in 7 eyes, non-inferior to elevated blebs in IOP control.</p> Conclusions <p>Trabeculectomy with subscleral tube placement provides effective, low-cost IOP reduction in refractory glaucoma, while preserving vision.</p>