Low Versus High Intraoperative Intraocular Pressure During Phacoemulsification Cataract Surgery: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Objective: To conduct a systematic review and meta-analysis of randomized controlled trials (RCTs) comparing low versus high intraoperative intraocular pressure (IOP) during phacoemulsification. Methods: PubMed, Scopus, Web of Science (WoS), and CENTRAL were searched from inception through 6 July 2026, followed by a supplementary manual search conducted before data extraction on 5 August 2026, to identify any additional eligible studies. RCTs comparing low-IOP versus high-IOP strategies during phacoemulsification were included. Outcomes were categorized as intraoperative, postoperative, and safety outcomes. Data were pooled as mean differences (MDs) or risk ratios (RRs) with corresponding 95% confidence intervals (CIs) using random-effects models. Results: Twelve RCTs comprising 1051 eyes were included. Cumulative dissipated energy was comparable between low- and high-IOP strategies (MD −0.12, 95% CI −0.45 to 0.20; p = 0.42). No significant between-group differences were observed in endothelial cell density, best-corrected visual acuity, central corneal thickness, or postoperative IOP across the reported follow-up periods (all p > 0.05). Intraoperative pain, aspiration time, total case time, fluid usage, and safety outcomes were also comparable between groups. Low-IOP phacoemulsification was associated with a modest increase in total ultrasound time (MD 1.53 s, 95% CI 0.03 to 3.03; p = 0.047). Conclusions: Low-IOP phacoemulsification provides intraoperative, postoperative, and safety outcomes broadly comparable to high-IOP strategies. Despite a statistically significant but clinically negligible increase in ultrasound time of approximately 1.5 s in favor of low-IOP, no significant differences were observed in cumulative dissipated energy, endothelial cell density, best-corrected visual acuity, central corneal thickness, postoperative IOP, or safety outcomes. However, these findings should not be interpreted as definitive evidence of equivalence or non-inferiority between the two strategies.