Minimally invasive glaucoma surgery: comparison of Hydrus microstent with iStent inject in primary open-angle glaucoma

Background To evaluate and compare the efficacy of a single Hydrus and double iStent inject both combined with cataract surgery for the treatment of primary open-angle glaucoma (POAG).Methods The study was designed as a prospective comparative case series. Patients with POAG undergoing trabecular microbypass stent insertion in addition to cataract surgery were recruited and consent was obtained. Baseline demographic information and preoperative, intraoperative and postoperative outcomes including intraocular pressure (IOP), visual acuity and topical glaucoma medication use were recorded and analysed. Treatment outcomes were analysed after propensity score matching to adjust for baseline differences between the two groups. Primary success was defined as an IOP of <= 18 and >= 20% IOP reduction at 12 months; other outcomes included IOP <= 15 mm Hg and <= 21 mm Hg. These were measured against complete success (no medications) and qualified success (one or more medications).Results The study comprised 85 eyes in the Hydrus group and 100 eyes in the iStent inject group at commencement, with 12-month follow-up for 85 and 78, respectively. When correcting for baseline differences between the two groups using propensity score matching, Hydrus eyes were not more likely to achieve primary success (average treatment effect -0.79, p=0.15).Conclusion After adjusting for baseline differences, there was no statistically significant difference between combined Hydrus microstent implantation and cataract surgery when compared with the iStent inject in reducing IOP at 12-month follow-up. This study was limited by statistically significant baseline differences between the two study groups, adjusted for with propensity score matching.