Associations with intraocular pressure across Europe: The European Eye Epidemiology (E$^3$) Consortium

Raised intraocular pressure (IOP) is the most important risk factor for developing glaucoma, the second commonest cause of blindness globally. Understanding associations with IOP and variations in IOP between countries may teach us about mechanisms underlying glaucoma. We examined cross-sectional associations with IOP in 43,500 European adults from 12 cohort studies belonging to the European Eye Epidemiology (E$^3$) consortium. Each study conducted multivariable linear regression with IOP as the outcome variable and results were pooled using random effects meta-analyzis. The association of standardized study IOP with latitude was tested using meta-regression. Higher IOP was observed in men (0.18 mmHg; 95 % CI 0.06, 0.31; $\small \textit{P}$ = 0.004) and with higher body mass index (0.21 mmHg per 5 kg/m2 ; 95 % CI 0.14, 0.28; $\small \textit{P}$ < 0.001), shorter height (-0.17 mmHg per 10 cm; 95 % CI –0.25, -0.08; $\small \textit{P}$ < 0.001), higher systolic blood pressure (0.17 mmHg per 10 mmHg; 95 % CI 0.12, 0.22; $\small \textit{P}$ < 0.001) and more myopic refraction (0.06 mmHg per Dioptre; 95 % CI 0.03, 0.09; $\small \textit{P}$ < 0.001). 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. We found no significant association between standardized IOP and study location latitude ($\small \textit{P}$ = 0.76). Novel findings of our study include the 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. Despite the limited range of latitude amongst included studies, this finding is in favour of collaborative pooling of data from studies examining environmental and genetic determinants of IOP in Europeans.Medical Research Council (G1000143), Cancer Research UK (C864/A14136), Research into Ageing (262), Wellcome Trust, Richard Desmond Charitable Trust (via Fight for Sight), National Institute for Health Research, Stichting Lijf en Leven, Krimpen aan de Lek, MD Fonds, Utrecht, Rotterdamse Vereniging Blindenbelangen, Rotterdam, Stichting Oogfonds Nederland, Utrecht, Blindenpenning, Amsterdam, Blindenhulp, The Hague, Algemene Nederlandse Vereniging ter Voorkoming van Blindheid (ANVVB), Doorn, Landelijke Stichting voor Blinden en Slechtzienden, Utrecht, Swart van Essen, Rotterdam, Stichting Winckel-Sweep, Utrecht, Henkes Stichting, Rotterdam, Lameris Ootech BV, Nieuwegein, Medical Workshop, de Meern, NWO (Graduate Programme 2010 BOO (022.002.023)), Laboratoires Thea (Clermont-Ferrand, France), inter regional grant (PHRC) and the regional Council of Burgundy, European Community’s Seventh Framework Programme (FP7/2007-2013), Rheinland-Pfalz AZ 961-386261/733), Johannes Gutenberg-University of Mainz, Boehringer Ingelheim, PHILIPS Medical Systems, Novartis Pharma, Novartis  European Union (European Social Fund—ESF), Greek National Strategic Reference Framework (NSRF) (Research Funding Program: THALES), European Social FundThis is the final version of the article. It first appeared from Springer via http://dx.doi.org/10.1007/s10654-016-0191-