1.2

Environmental Risk Factors for

Myopia in Children

Wilson C.J. Low*, Tien-Yin Wong*,†,‡,§ and Seang-Mei Saw*,‡

Introduction

In Caucasian populations, approximately 20% to 25% of individuals develop myopia.1 In contrast, the prevalence of myopia is much higher, reaching epidemic levels of up to 80% in selected regions of Asian countries, such as Taiwan, Hong Kong, and Singapore.2–4 Myopia is a major public health problem because of under-correction and undiagnosed cases, which can lead to visual impairments and potentially blinding ocular complications.5 Myopia also poses a direct economic burden resulting from the cost of refractive correction through repeat optometry visits and prescription of eyeglasses, contact lenses, and refractive surgery.6 In Singapore, the mean annual direct cost of myopia for each schoolchild aged 7 to 9 years is US$148.7 Myopia is a complex eye disease, in which both genetic and environmental factors contribute to its development.8 Twin heritability, familial aggregation, pedigree segregation, and linkage studies provide evidence to support a major genetic component influencing myopic development.9–12 Additionally, environmental factors such as near work and outdoor activities appear to also play an important role in the development of myopia.13–15 This chapter aims to provide a summary of the known as well as controversial risk factors for myopia and ocular biometry in children, including family

*Department of Epidemiology and Public Health, Yong Loo Lin School of Medicine, National University of Singapore, Singapore. E-mail: g0801125@nus.edu.sg

†Centre for Eye Research Australia, University of Melbourne, Australia.

‡Singapore Eye Research Institute, Singapore.

§Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.

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