Intraocular pressure and corneal biomechanics in an adult British population: the EPIC-Norfolk eye study.

PURPOSE To describe the distribution and determinants of intraocular pressure (IOP) and indices of corneal biomechanics in an adult British population. METHODS Goldmann-equivalent IOP (IOPg), corneal mechanical characteristics (corneal hysteresis, CH; corneal resistance factor, CRF), and IOP adjusted for corneal factors (IOPcc) were measured. Ocular biometric characteristics were also measured in 4184 consecutive individuals aged 48 to 91 years recruited from the European Prospective Investigation into Cancer (EPIC)-Norfolk cohort. Sociodemographic data were recorded with a standardized questionnaire. Blood pressure and anthropometric data were recorded by trained staff according to a standard protocol. RESULTS Mean IOP was similar to that reported in previous United Kingdom population studies (IOPg: 16.0 mm Hg, SD 3.68). These data confirmed systolic blood pressure as the major identifiable correlate of IOP. There was a significant positive association between IOP and axial length of the eye. The IOPg, but not IOPcc, was higher in the women than in the men. No difference in IOP between the different age groups was identified. CRF and CH varied with IOPg, age, sex, and axial length of the eye. CONCLUSIONS The study provided current population-based values for IOP and corneal biomechanical parameters. Mean IOP in this British population was very similar to levels previously reported over 40 years ago. There was no identifiable relationship between IOP and age within this cohort with an older age range, in contrast to previous studies. Systolic blood pressure was identified as the major correlate of IOP.