Refractive error and biometry in older Chinese adults: the Liw...

PURPOSE: To assess the prevalence of refractive error and describe the distribution of ocular biometry and its association with refraction in adult Chinese. METHODS: Random clustering sampling was used to identify adults aged > or = 50 years in Liwan District, Guangzhou. Refraction was determined by subjective refraction that achieved the best corrected vision based on monocular measurement. Ocular biometry was measured by A-mode ultrasound using a handheld applanation probe. RESULTS: Among 1405 participants in the study, data from 1269 phakic right eyes were available for analysis. The prevalence of myopia (SE < -0.5 D), hyperopia (SE > +0.5 D), and astigmatism (cylinder > 0.75 D) was 32.3% (95% confidence interval [CI], 27.8%-34.6%), 40.0% (95% CI, 37.3%-42.7%), and 48.3% (95% CI, 45.6%-51.1%), respectively. The spherical equivalent tended to become hyperopic at 60 years and shifted toward myopia at 75 years. Axial length did not change with age but was consistently shorter in women. Lens thickness increased with age and tended to be greater in women. CONCLUSIONS: The prevalence of myopia and biometric distribution in this urban Chinese cohort are similar to those observed in Singaporean Chinese but greater than in Mongolians and Europeans. Further studies are needed to clarify the role of environmental factors in the myopia rates.