iStent combined with phacoemulsification versus phacoemulsification alone in open-angle glaucoma: a meta-analysis by medication washout status

To assess how preoperative medication washout influences the interpretation of intraocular pressure (IOP) outcomes in randomized controlled trials (RCTs) comparing iStent combined with phacoemulsification versus phacoemulsification alone. Systematic searches in PubMed, Embase, Web of Science, Cochrane Library, and ClinicalTrials.gov were conducted through December 2025. RCTs comparing combined surgery versus phacoemulsification alone in open-angle glaucoma were included. Random-effects meta-analyses pooled weighted mean differences (WMDs) for IOP and medications, stratified by washout status and follow-up duration. Five RCTs (915 eyes) were included. In short-term follow-up (≤ 15 months), IOP reduction did not differ significantly between groups. In long-term follow-up (> 15 months), combined surgery showed greater IOP reduction in trials with medication washout (WMD = 1.29 mmHg; 95% CI: 0.61 to 1.97) but not in trials without washout (WMD = 0.69 mmHg; 95% CI: −2.25 to 3.63). Combined surgery consistently reduced medication use (WMD = 0.39) and increased the likelihood of medication-free status (RR = 1.31; 95% CI: 1.15 to 1.51). Preoperative washout status substantially influences IOP outcome quantification. In patients assessed without washout, where baseline IOP is medically controlled, the principal benefit of combined surgery is sustained medication burden reduction rather than additional numerical IOP lowering.