Five-Year Outcomes of First-Generation iStent Versus Hydrus Microstent Implantation Combined with Phacoemulsification in Patients with Open-Angle Glaucoma: A Prospective Non-Randomized Comparative Study

Background: This study assessed the 5-year clinical outcomes of phacoemulsification combined with implantation of either the first-generation iStent Trabecular Micro-Bypass or the Hydrus Microstent in eyes with open-angle glaucoma. Methods: In this prospective, non-randomized comparative study, 65 eyes of 65 patients underwent combined cataract and micro-invasive glaucoma surgery with either iStent or Hydrus implantation. Intraocular pressure (IOP), number of glaucoma medications, best-corrected visual acuity (BCVA), surgical success, postoperative complications, and subsequent glaucoma procedures were analyzed over a 60-month follow-up. Results: At 60 months, outcome data were available for 47 eyes (72.3%), including 25 eyes in the iStent group and 22 eyes in the Hydrus group. Baseline characteristics did not differ significantly between groups. Mean IOP at 60 months was similar after iStent and Hydrus implantation (16.7 ± 1.8 mmHg vs. 16.5 ± 1.9 mmHg, respectively). The mean number of glaucoma medications decreased from 1.86 ± 0.94 to 1.36 ± 1.08 in the iStent group and from 1.60 ± 0.72 to 0.36 ± 0.49 in the Hydrus group, with significantly fewer medications required after Hydrus implantation at 60 months. Medication-free complete surgical success using the IOP ≤ 18 mmHg criterion was achieved in 20.0% of iStent-treated eyes and 63.6% of Hydrus-treated eyes. No eye underwent additional glaucoma surgery or selective laser trabeculoplasty during follow-up. Conclusions: In this prospective non-randomized comparative cohort, both procedures provided comparable long-term treated IOP control when combined with phacoemulsification. Hydrus implantation was associated with a greater medication-sparing effect and a higher proportion of medication-free complete surgical success at 5 years; however, these findings should be interpreted in the context of the non-randomized design and available-case follow-up.