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Anthony P Khawaja, Henriet Springelkamp, Nomdo M Jansonius, Paul J Foster, ; Associations with intraocular pressure across Europe: The European Eye Epidemiology (E3) Consortium. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):4338.
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© ARVO (1962-2015); The Authors (2016-present)
Previous population studies examining intraocular pressure (IOP) have had limited statistical power to identify small associations, and have not compared IOP between countries. The European Eye Epidemiology (E3) consortium is a collaborative network of population-based studies. We conducted a large cross-sectional study of Europeans from 12 studies in 6 countries, with the aim of identifying systemic and ocular associations with IOP, and to test for an association between latitude and IOP.
IOP was measured using Goldmann applanation tonometry in 6 studies and non-contact tonometry in 6 studies. Mean IOP of right and left eyes was used in analyses. We excluded participants with a history of glaucoma. Each study conducted multivariable linear regression analysis with IOP as the outcome variable, and age, sex, height, body mass index (BMI), systolic blood pressure (SBP) and spherical equivalent (SE) together as explanatory variables. Results from each study were pooled using random effects meta-analysis. The association between age and IOP was further tested stratified into age groups. A standardized IOP was calculated for each study using set values for covariables (age 65 yrs, sex 1.5, SBP 135 mmHg, height 165 cm, BMI 25 Kg/m2, SE 0 D) and association of standardized IOP with latitude was tested using meta-regression.
We analysed data from 43,500 phakic participants aged 49 to 81 years. As shown in the Table, higher IOP was observed in men (P=0.004) and with higher BMI (P<0.001), shorter height (P<0.001), higher SBP (P<0.001) and more myopic refraction (P<0.001). A Forest plot for the height association is shown in the Figure. An inverted U-shaped trend was observed between age and IOP, with IOP increasing up to the age of 60 and decreasing in participants older than 70 years (Table). Mean standardized IOP for all studies was 14.8 mmHg (95% CI 14.3, 15.3). We found no significant association between standardized IOP and study location latitude (P=0.76).
We report a novel association of lower IOP in taller people, and an inverted-U shaped association of IOP with age. We found no evidence of significant variation in IOP across Europe, supporting the necessary collaborative pooling of data from studies examining the genetic determinants of IOP in Europeans.
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