Purpose <p>To report the three-year clinical outcomes and safety profile of standalone PreserFlo MicroShunt implantation.</p> Methods <p>A single-center, retrospective study of 151 eyes from 109 patients with open-angle glaucoma who underwent standalone microshunt implantation between February 2019 and December 2020.</p> Results <p>The mean IOP decreased significantly from 22.64 ± 8.79mmHg preoperatively to 12.76 ± 3.93mmHg three years postoperatively, with a mean IOP reduction of 43.6% (<i>p</i> = &lt; 0.001). The need for IOP-lowering medication was significantly reduced from 2.64 ± 1.15 at baseline to 0.71 ± 1.12 after three years, representing a mean reduction of 73.1% (<i>p</i> = &lt; 0.001). Three years post-implantation, 64.41% of eyes were free of glaucoma medication. Qualified and complete surgical success (IOP ≤ 21mmHg) was achieved in 77.6% and 42.3% of eyes, respectively, at three years. The most common complications were transient ocular hypotony (40.4%), choroidal detachment (13.25%), hyphema (11.92%). The vast majority of complications were self-limiting and did not pose a threat to vision. Open revision surgery was necessary in 14 eyes (9.27%). 7 eyes (4.63%) underwent further glaucoma surgery due to surgical failure. No statistically significant reduction in endothelial cell density (ECD) was observed 3 years after microshunt implantation (<i>n</i> = 13; <i>p</i> = 0.526).</p> Conclusion <p>PreserFlo MicroShunt implantation is an effective surgical technique for lowering intraocular pressure and reducing the need for antiglaucoma medication while maintaining a favorable safety profile. Its effect remains stable three years after surgery.</p>