Purchase this article with an account.
N. G. Congdon, L. Chen, M. Zhang, L. Li, J. Wu, J. Lee, A. Yang, D. Xu, C. Chen, D. S. C. Lam; Population Density and Refractive Error Among Chinese Children. Invest. Ophthalmol. Vis. Sci. 2010;51(13):2967.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To better understand the reasons for observed differences in urban versus rural myopia prevalence among Chinese children.
Cycloplegic refractive error was measured among all children with uncorrected acuity <= 6/12, and a 50% random sample of children with vision > 6/12 at all junior and senior high schools in mixed rural-urban Liangying Township, Guangdong, China. Questionnaires were used to ascertain age, gender, parental education, near work (measured as diopter-hours based on self-reported time and working distance), self-reported time outdoors and development level of the respondent's neighborhood (15-item questionnaire). Population density for each of 32 villages/urban zones in Liangying was calculated from census figures (mean population density 217 persons/km2, range 94 to 3738/km2, mean for Guangdong 486/km2, China 139/km2).
Among 5844 children of consenting parents, 4612 (78.9%) completed examinations, 2960 were refracted per protocol and 2584 (87.3%) of these had questionnaire data. Those with completed exams were more likely to be girls (P < 0.001) and questionnaire respondents were slightly (2 months, P = 0.002) older, but otherwise did not differ significantly from non-respondents. In multivariate models, older age (P = 0.01), more near work (P < 0.0001) and higher population density (P = 0.009), but not development index (P = 0.23), parental education or time outdoors, were significantly associated with more myopic refractive error.
Higher population density appears to be associated with myopia risk independent of academic activity, time spent outdoors, familial educational level or economic development, factors which have in the past been thought to explain urban-rural differences in myopia prevalence. Biological mechanisms underlying this apparent effect should be sought.
This PDF is available to Subscribers Only