Epidemiologic Characteristics of Intraocular Pressure in the Korean and Mongolian Populations: The Healthy Twin and the GENDISCAN Study

Abstract

Purpose: The purpose of this study was to demonstrate a negative association between intraocular pressure(IOP) and age in 2 Asian populations. In addition, we evaluated genetic and nongenetic factors associated withIOP.Design: Family-based cohort study.Participants: Study subjects 10 years of age from one Korean (The Healthy Twin; n 1431) and 2Mongolian populations (The GENDISCAN; n 859 and 806) with IOP values.Methods: The IOP values were measured with a noncontact tonometer. Each participant received astandard health examination and received questionnaires, which include candidate risk factors on IOP. Mixedmodels were used to identify risk factors for IOP. Variance-component methods were applied to estimate theheritability of IOP.Main Outcome Measures: The negative trend of IOP with aging and evaluation of impact of genetic andnongenetic components on IOP.Results: The mean ages were 43.6, 34.1, and 36.3 years for the Korean, Orhontuul, and Dashbalbarpopulations, respectively. The mean IOPs were 14.4 mmHg (95% confidence interval [CI], 14.3.14.6) in theKoreans and 14.1 mmHg (95% CI, 13.9.14.3) and 12.6 mmHg (95% CI, 12.4.12.9) in the Orhontuul andDashbalbar populations, respectively. In the 3 populations, the IOP decreased as age increased. We replicatedan association of systolic blood pressure (SBP) with IOP. In addition, components of the metabolic syndrome(MS), such as plasma glucose, lipid level, and body mass index, showed positive associations with IOP, afteradjusting for age and SBP. The IOP also had strong genetic contributions in all populations (heritability,0.47.0.51).Conclusions: Negative associations between age and IOP were observed in all 3 populations, which cannotbe explained by the increasing prevalence of myopia in the younger generation. The different age trend in IOPmay in part be responsible for differences in the prevalence of glaucoma subtypes. Our findings suggest thatassociations between IOP and MS components were independent of established risk factors such as SBP or age.In addition, the importance of inherited risks requires further genetic dissection of IOP determinants for biologicalunderstandings of underlying pathophysiology.Financial Disclosure(s): The authors have no proprietary or commercial interest in any materials discussedin this article. Ophthalmology 2011;xx:xxx ⓒ 2011 by the American Academy of Ophthalmology.