AIM: To investigate the effect of pharmacological pupil alterations on intraocular lens (IOL) power calculations. METHODS: A systematic review and Meta-analysis of studies published before December 2023 in the PubMed, Embase, and Cochrane library databases on the accuracy of pharmacological pupil changes on IOL power calculation was performed. The primary outcome was the results of IOL power calculations before and after the use of medications. Subgroup analyses were performed based on participants’ basic characteristics, such as age, axial length (AL), and whether miosis or mydriasis were used as classification criteria for further analyses. Each eligible study was evaluated for potential risk of bias by the AHRQ assessment scale. The study was registered on PROSPERO (CRD 42024497535). RESULTS: A total of 3062 eyes from 21 studies were eligible. There was no significant difference in the IOL power calculation before and after pharmacological pupil changes using any of the Hoffer Q (WMD=0.055, 95%CI=-0.046–0.156; P=0.29), SRK/T (WMD=0.003, 95%CI=-0.073–0.080; P=0.93), Haigis (WMD=-0.030, 95%CI=-0.176–0.116; P=0.69), Holladay 2 (WMD=-0.042, 95%CI=-0.366–0.282; P=0.80), and Barrett Universal II (WMD=0.033, 95%CI=-0.061–0.127; P=0.49) formulas. On the measurement of parameters related to IOL power calculation, for either miosis or mydriasis AL (P=0.98 and 0.29, respectively), lens thickness (P=0.96 and 0.13, respectively), and mean keratometry (P=0.90 and 0.86, respectively) did not present significant differences, while anterior chamber depth (P=0.07 and <0.01, respectively) and white-to-white distance (P=0.01 and 0.04, respectively) changed significantly between the two measurements prior and posterior. At the same time, despite there being some participants with the difference between the before and after calculations greater than 0.5 diopter, there was no significant difference in the incidence rate between these formulas. CONCLUSION: There is no significant effect of pharmacological pupil changes on the IOL power calculation. It will considerably reduce the visit time burden for patients who require cataract surgery.