Underestimation of Intraocular Pressure (IOP) After LASIK and PRK: Systematic Review and Meta-Analysis

Background/Objectives: Refractive corneal surgery alters corneal biomechanics and thickness, affecting the accuracy of intraocular pressure (IOP) measurements. This systematic review and meta-analysis aimed to quantify the postoperative underestimation of IOP following such procedures. Methods: This systematic review and meta-analysis, conducted based on PRISMA guidelines, evaluated pre- and postoperative IOP changes following LASIK and PRK using GAT, ORA, and CORVIS ST, based on studies identified through PubMed, Scopus, Cochrane Library, and ScienceDirect up to 31 December 2025, with results synthesized using random-effects models and reported as mean differences (MD) with 95% confidence intervals (CI). Results: Of the 1796 articles identified, 54 studies met the inclusion criteria, encompassing a total of 4730 eyes. After LASIK, a statistically significant underestimation of IOP was observed with all methods: GAT (MD: 3.23 mmHg, 95% CI: 2.77-3.69, p < 0.001), ORA (MD: 2.13 mmHg, 95% CI: 1.56-2.70, p < 0.001), and CORVIS ST (MD: 1.39 mmHg, 95% CI: 0.53-2.24, p = 0.001). Similarly, after PRK, a significant reduction in IOP was recorded with GAT (MD: 2.04 mmHg, 95% CI: 1.24-2.84, p < 0.001) and ORA (MD: 2.46 mmHg, 95% CI: 0.62-4.29, p < 0.01), while the difference measured by CORVIS ST was not statistically significant. Conclusions: LASIK and PRK result in systematic underestimation of IOP, most pronounced with GAT and less evident with ORA and CORVIS ST, highlighting the importance of selecting appropriate tonometry methods for accurate monitoring, especially in patients at risk of glaucoma or elevated IOP.