Intraocular Pressure, Ethnicity and Refractive Error in the Collaborative Longitudinal Evaluation of Ethnicity and Refractive Error (CLEERE) Cohort

Abstract

Purpose:: The large ethnically diverse CLEERE cohort provides a unique opportunity to explore associations between intraocular pressure (IOP), ethnicity and refractive error (RE) while adjusting for potentially confounding variables.

Methods:: Cross-sectional data from the first study visit (1995 to 2003) were used for 4405 children 6 to 16 years old. IOP was measured by Tono-Pen (Mentor XL), RE by cycloplegic autorefraction and ethnicity by parent report. Regression methods were used to examine the relationship of age, RE and ethnicity with IOP. Only IOP differences that are both statistically significant and clinically meaningful (> 2mm) are considered relevant.

Results:: Differences in IOP among the refractive error groups were noted in models adjusting for age and ethnicity but all statistically significant differences were less than 1mmHg (greatest difference = 0.94mmHg with IOP of emmetropes [-0.75 to +1D] > hyperopes [≥ 2.5D]). Adjusting for RE, IOP varied by age and ethnicity. For Native Americans, IOP was stable across age with a 0.5mmHg decrease from age 6 to 15. At age 6, Whites and African Americans had the highest mean IOP (19.31 and 19.03mmHg, respectively) and Native Americans and Asians the lowest (15.43 and 16.75mmHg, respectively). IOP decreased with age in African Americans, Whites and Hispanics (>2.5mm across 8 years) but increased in Asians (>1.5mmHg). By age 12 years the IOP of Asians was 2.5mmHg higher than Whites and African Americans, 2.7mmHg higher than Native Americans, and 4mmHg higher than Hispanics.

Conclusions:: Cross-sectional analysis of this large and ethnically diverse cohort showed interesting differences in IOP by age and ethnicity but not by refractive error. Interactions between RE and age and/or ethnicity may be responsible for previous reports of associations between refractive error and IOP in children.

Keywords: intraocular pressure • clinical (human) or epidemiologic studies: prevalence/incidence