To evaluate the safety and effectiveness of the Ahmed ClearPath® (ACP) 250 mm2 glaucoma drainage device (GDD) in managing refractory primary open-angle glaucoma (POAG).This was a retrospective case series focused on adult patients diagnosed with severe POAG who underwent implantation of an ACP GDD. Over a 36-month follow-up period, data on intraocular pressure (IOP), the number of glaucoma medications, and complications were recorded. The primary objectives were to assess the reductions from baseline in both IOP and medication usage, through 36 months. Secondary objectives included the proportion of eyes achieving an IOP reduction of ≥ 20% from baseline at 36 months. Intraoperative and postoperative complications were also assessed.Twelve eyes from 11 patients (mean age: 71.3 ± 14.1 years) met the inclusion criteria and were included in the study. All patients had severe POAG (n=11), with the majority being Caucasian (n=8) and female (n=10). The mean (standard deviation) IOP and number of glaucoma medications at baseline were 29 (7.6) mmHg and 3 (0.9), respectively. At 36 months, mean IOP was reduced to 10.6 (5.5) mmHg (-61.8%; p= 0.0008) and mean number of medications was reduced to 0.9 (0.9) (-71.4%; p=0.0005), with 88.9% of eyes achieving an IOP reduction by ≥20%. No vision threatening complications were observed.To our knowledge this is the first study to report 36-month outcomes of the novel ACP device in the treatment of refractory POAG. The safety profile and efficacy of the ACP was found to be comparable to that of other commonly utilized GDD models.