Intraocular Pressure, Central Corneal Thickness, and Glaucoma in Chinese Adults: The Liwan Eye Study

PURPOSE: To describe the distribution of central corneal thickness (CCT), intraocular pressure (IOP), and their determinants and association with glaucoma in Chinese adults. DESIGN: Population-based cross-sectional study. METHODS: Chinese adults aged 50 years and older were identified using cluster random sampling in Liwan District, Guangzhou. CCT (both optical [OCCT] and ultrasound [UCCT]), intraocular pressure (by Tonopen, IOP), refractive error (by autorefractor, RE), radius of corneal curvature (RCC), axial length (AL), and body mass index (BMI) were measured, and history of hypertension and diabetes (DM) was collected by questionnaire. Right eye data were analyzed. RESULTS: The mean values of OCCT, UCCT, and IOP were 512 +/- 29.0 mu m, 542 +/- 31.4 mu m, and 15.2 +/- 3.1 mm Hg, respectively. In multiple regression models, CCT declined with age (P < .001) and increased with greater RCC (P < .001) and DM (P = .037). IOP was positively associated with greater CCT (P < .001), BMI (P < .001), and hypertension (P < .001). All 25 persons with open-angle glaucoma had IOP <21 mm Hg. CCT did not differ significantly between persons with and without open- or closed-angle glaucoma. Among 65 persons with ocular hypertension (IOP >97.5th percentile), CCT (555 29 gm) was significantly (P = .01) higher than for normal persons. CONCLUSIONS: The distributions of CCT and IOP in this study are similar to that for other Chinese populations, though IOP was lower than for European populations, possibly due to lower BMI and blood pressure. Glaucoma with IOP <21 mm Hg is common in this population. We found no association between glaucoma and CCT, though power (0.3) for this analysis was low. (Am J Ophthalmol 2011;152:454-462. (C) 2011 by Elsevier Inc. All rights reserved.)