Abstract
Purpose To compare the axial length difference (ALD) and the estimated generational axial length shift (ALS) from parents to their children and its risk factors in urban and rural China. Methods Participants were enrolled from two longitudinal cohort studies, the Beijing Myopia Progression Study (BMPS) and the Handan Offspring Myopia Study (HOMS). Ocular biometry was performed in both parents and their children. ALD was defined as the difference between the children's axial length and the corresponding parental axial length. Generational ALS was estimated according to a binominal prediction model at 18 years of age. Results 237 and 380 urban and rural Chinese children (6–17 years) and their parents from the BMPS and HOMS, respectively, were enrolled. Children's axial length was estimated to be closest to the parental axial length at 11 and 9 years of age in the urban and rural areas, respectively; the estimated generational ALS would be 1.53 and 0.57 mm, respectively. Multivariable regression analysis revealed that older children (urban β = 0.26, p < 0.001; rural β = 0.11, p < 0.001) and males had larger ALD (urban β = 0.55, p < 0.001; rural β = 0.52, p < 0.001) in both areas. Furthermore, urban children with more educated parents (fathers: β = −0.30, p=0.002; mothers: β = −0.29, p=0.004) and more outdoor activity (β = −0.23, p=0.006) had a less ALD. Conclusions The urban generational axial length shift was estimated to be approximately 1 mm longer than that of the rural area. These results suggest different environmental effects on the ocular development in these two populations of Chinese children.
Highlights
Myopia in school children is a major public health problem in both rural and urban populations in East Asia [1, 2]
It is noteworthy that these two studies shared many of the same procedures and questionnaires with Beijing Myopia Progression Study (BMPS) [10, 12]. e BMPS and Handan Offspring Myopia Study (HOMS) followed the tenets of the Declaration of Helsinki and were approved by the ethics committee of Beijing Tongren Hospital and Handan Eye Hospital, respectively
The vitreous chamber depth showed the greatest change in the urban children, indicating that posterior segment elongation was an important reason for myopic progression in children with moderate refractive error
Summary
Myopia in school children is a major public health problem in both rural and urban populations in East Asia [1, 2]. Both genetic and environmental factors may play important roles in the development of myopia [3, 4]. Different environment factors were believed to reflect their different generational myopia shifts [5, 6]. Since the incidence of juvenile myopia is high in East Asia [1, 9], investigation of variations in the ocular parameters between generations may enable better understanding of both the mechanisms and risk factors that lead to eye growth and myopia
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