PURPOSE: To evaluate the real-world efficacy and safety of iStent implanted standalone or combined with phacoemulsification in open-angle glaucoma (OAG) patients. METHODS: This is a retrospective observational study of OAG patients who underwent standalone or combined iStent procedures were reviewed. Inclusion criteria included age over 18 years and open angle on gonioscopy. Exclusion criteria were prior incisional glaucoma surgeries, missing data, or follow-up shorter than 6 months. The primary outcome was surgical success between the two groups after one year. Secondary outcomes included differences in IOP reduction and medication use. RESULTS: We included 48 eyes with primary (n = 44) and secondary OAG (n = 4). Nineteen eyes had standalone while 29 eyes had combined procedures. Kaplan-Meier analysis revealed overall surgical success in 31.3% of eyes after one year. Qualified success was higher in the combined group than the standalone group [62.5% (10 eyes) vs 27.3% (3 eyes), p = 0.239]. At 24 months, mean IOP reduced by 2.2 ± 2.5 mmHg vs 3.3 ± 2.9 mmHg, p = 0.333), and the number of medications reduced by 1.1 ± 1.2 vs 1.3 ± 0.1, p <
0.001) in the standalone and combined group, respectively. Stent occlusion occurred in two eyes. CONCLUSIONS: While both standalone and combined iStent procedures provide safe IOP reduction throughout 12 months, there was no statistically significant difference in surgical success between them.