The effect of central corneal thickness on intraocular pressure in healthy subjects: a systematic review and meta-analysis

Introduction This study aimed to evaluate the independent effects of central corneal thickness (CCT), age, and tonometer type on intraocular pressure in healthy populations.Methods We searched PubMed, Embase, Scopus, ScienceDirect, and the Cochrane Library from inception to December 2025. Sixty-one cross-sectional studies comprising 8,264 participants were included. A random-effects was performed to pool mean IOP. Subgroup analyses were conducted based on CCT, age, and tonometer type (Goldmann, iCare, Ocular Response Analyzer, Pascal, Tonopen, Corvis, and non-contact tonometers). Heterogeneity was assessed using I2 statistic.Results This meta-analysis establishes a global normative IOP of approximately 14.9 mmHg. The critical finding is that IOP values are fundamentally device-specific and not be used interchangeably. CCT remains a major confounder; measured IOP increases from 13 mmHg at 490 µm to 17 mmHg at 610 µm. A significant effect of age on IOP revealed that individuals under 20 years and those between 40–60 years exhibited elevated pooled mean IOP, while the lowest pressures were observed in the 20–40‑year and over‑60‑year subgroups. Conclusion The normative IOP in healthy populations is shaped by tonometer type, central corneal thickness, and age. The relationship between age and IOP highlights age as a distinct factor that must be accounted for in clinical and research settings.