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

https://doi.org/10.1016/j.ajo.2011.03.005Get rights and content

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 μm, 542 ± 31.4 μm, 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 μm) 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.

Section snippets

Materials and Methods

The detailed study protocol has been reported elsewhere.22 In brief, subjects were enrolled from a population-based study conducted among residents of Liwan District, Guangzhou City, aged 50 years and above using cluster random sampling. Fieldwork was carried out between September 10, 2003 and February 14, 2004.

A standard questionnaire was administered by a trained interviewer. DM and hypertension were defined based on self-reported history of a diagnosis or previous medication use. Height and

Results

In total, 1865 people were identified as eligible in the sampling district. Among them, 1405 (75.4%) were successfully examined. Reasons for nonparticipation included 168 refusals (9%), 66 (3.5%) severely ill or physically disabled, and 226 (12.1%) who could not be contacted after at least 3 home visits. In general, people aged 80 years and over were less likely to participate than other age groups. Among the 1405 subjects, 12 did not have IOP data available. Optical CCT data were missing for

Discussion

This is the first study to provide population-based data on IOP and CCT distribution as well as their determinants in southern China. Both optical and ultrasound pachymetry data are available, allowing direct comparison with most existing studies.

The inter-ethnic comparison of CCT in population studies is summarized in Table 6. Our optical and ultrasound CCT values were 512 ± 29.0 μm and 542 ± 31.4 μm respectively, which were consistent with the results reported by a meta-analysis (510-519 μm

Dandan Wang, MD, graduated from Sun Yat-sen University of Medical Science, Guangzhou, China. She completed her ophthalmology training at the Zhongshan Ophthalmic Center and was certified by the China Board of Ophthalmology in 2005. She underwent further training in glaucoma at the University of California, San Francisco, in 2007. Dr. Wang currently serves as a postdoctoral research associate at the Doheny Eye Institute of the University of Southern California. Her research is mainly focused on

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    Dandan Wang, MD, graduated from Sun Yat-sen University of Medical Science, Guangzhou, China. She completed her ophthalmology training at the Zhongshan Ophthalmic Center and was certified by the China Board of Ophthalmology in 2005. She underwent further training in glaucoma at the University of California, San Francisco, in 2007. Dr. Wang currently serves as a postdoctoral research associate at the Doheny Eye Institute of the University of Southern California. Her research is mainly focused on the prevalence of eye disease among Chinese Americans.

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