Background <p>To evaluate the efficacy and safety of inferonasal quadrant (IN) Ahmed Valve implantation (AVI) using the double scleral tunnel technique in patients who had previously failed glaucoma surgery.</p> Methods <p>This retrospective comparative study included data from 69 patients diagnosed with refractory glaucoma who were followed in a tertiary referral hospital. The IN-AVI group included 35 patients who underwent IN-AVI after failed trabeculectomy or superotemporal quadrant (ST) AVI, and the ST-AVI group included 34 patients who underwent primary ST-AVI. The primary outcome was to analyse the surgical success rate, the secondary outcome was to compare the intraocular pressure (IOP) reduction in the IN-AVI and ST-AVI groups at 1-year postoperatively.</p> Results <p>Significant reduction in IOP was observed after IN-AVI at 1-year postoperatively (<i>p</i> &lt; 0.001). The overall success rate was 88.6%. IN-AVI after failed trabeculectomy didn’t differ from primary ST-AVI in terms of IOP reduction. IN-AVI after failed ST-AVI showed a lower IOP reduction compared to primary ST-AVI (<i>p</i> = 0.003). No tube exposure was observed at 1-year postoperatively using the double scleral tunnel technique.</p> Conclusions <p>In patients with refractory glaucoma, IN-AVI after failed trabeculectomy was as effective as the primary ST-AVI. Although IN-AVI after failed ST-AVI was effective in reducing IOP, it was significantly less effective than the primary ST-AVI. The prior failure of a trabeculectomy had no impact on the success of AVI. Conversely, a second AVI was less efficacious than the primary AVI.</p>