Caffeine Intake Effects on Intraocular Pressure in Healthy and Glaucomatous Populations: A Systematic Review and Meta-Analysis.

PURPOSE: To evaluate the effect of caffeine intake on intraocular pressure (IOP). METHODS: The PubMed, Cochrane, Scopus, and ProQuest databases were searched for publications of randomized trials investigating the effect of caffeine consumption on IOP in healthy and glaucomatous populations until February 1, 2025. Outcomes at 30 min, 1, 1.5, 2, and 3 h were analyzed using a random-effects model. Subgroup analysis was done for different types of caffeine-containing beverages and different amounts of caffeine. RESULTS: Sixteen studies, including 599 healthy participants and 63 glaucomatous patients (with primary open-angle glaucoma, ocular hypertension, and normotensive glaucoma), were included in this meta-analysis. The weighted mean difference (WMD) with 95% confidence intervals of IOP in the healthy population at 30 min, 1 h, 1.5 h, and 2 h were significant at 0.61 (0.07; 1.16), 0.87 (0.40; 1.33), 1.60 (0.40; 2.80), and 0.63 (0.03; 1.22), respectively. In glaucomatous patients, WMD at 1 and 1.5 h time points were significant at 1.51 (0.83; 2.18) and 1.39 (0.99; 1.78), respectively. Ingestion of >100 mg of caffeine significantly increased IOP at 30 min, 1, and 1.5 h, whereas ingestion of ≤100 mg did not significantly increase IOP in healthy populations. All included studies with glaucomatous populations used >100 mg of caffeine. CONCLUSION: Caffeine ingestion, especially of >100 mg, acutely elevates IOP in both healthy and glaucomatous populations.