Patterns of Daily Outdoor Light Exposure in Australian and Singaporean Children.

Scott A Read,Cheryl Ngo,Michael J Collins,Seang-Mei Saw,Stephen J Vincent,Chuen-Seng Tan

doi:10.1167/tvst.7.3.8

Abstract

PurposeMyopia is rising in prevalence in many locations, and there is evidence that outdoor light exposure is a major environmental factor playing a role in myopia development. This study examined the patterns of daily light exposure in similarly aged children from two geographic locations (Australia and Singapore) known to exhibit differences in myopia prevalence.MethodsWearable light sensors were used to assess daily light exposure in 69 Singaporean children aged 8 to 12 years (mean, 9.2 ± 1.1) and 43 Australian children aged 10 to 12 years (mean, 11.3 ± 0.6). The mean daily time exposed to bright outdoor light (>1000 lux) and the number and duration of daily episodes of outdoor exposure were examined.ResultsPatterns of daily outdoor light exposure differed substantially between Australia and Singapore. Australian children (105 ± 42 min/d) experienced significantly longer daily outdoor light exposure than Singaporean children (61 ± 40 min/d; P = 0.005), with the largest differences found on weekdays during school hours. Australian children (6.9 ± 1.5 episodes per day) had more frequent daily episodes of outdoor light exposure compared with Singaporean children (4.6 ± 1.5; P = 0.02); however, there was no significant difference in the mean duration of these episodes between countries (P = 0.54).ConclusionsChildren living in Singapore were exposed to significantly less daily outdoor light than Australian children, and these differences may be one of several factors contributing to the differences in myopia prevalence typically found between these populations.Translational RelevanceKnowledge of these light exposure patterns may assist in the design of outdoor interventions, including school programs, to increase outdoor time in urban Asian populations.

Highlights

Myopia typically occurs due to excessive axial eye growth in childhood and is one of the major causes of visual impairment in young populations.[1]
Analysis of these data revealed that the mean temperature was significantly warmer in Singapore, and significantly greater rainfall occurred in Singapore compared with Australia
This study provides the first intercountry comparison of personal objective measures of light exposure in children living in Australia and Singapore captured with wearable sensors, and demonstrates substantive differences in the magnitude and pattern of daily outdoor light exposure between the samples of children living in these two geographic locations

Summary

Introduction

Myopia typically occurs due to excessive axial eye growth in childhood and is one of the major causes of visual impairment in young populations.[1] In recent decades, there is evidence for substantial increases in the prevalence of myopia in many locations around the world,[2] in developed East Asian countries, such as Singapore,[3] Taiwan,[4] and Korea,[5] where epidemic levels (.80%) of myopia have been reported. These large differences in myopia prevalence associated with geographic location are unlikely to be due to ethnicity, because 6- to

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Conclusion