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Clinical science
Association of time outdoors and patterns of light exposure with myopia in children
  1. Mijie Li1,2,
  2. Carla Lanca2,
  3. Chuen-Seng Tan1,
  4. Li-Lian Foo3,4,
  5. Chen-Hsin Sun5,
  6. Fabian Yap6,
  7. Raymond P Najjar4,7,
  8. Charumathi Sabanayagam3,4,
  9. Seang-Mei Saw1,2,4
  1. 1 Saw Swee Hock School of Public Health, National University of Singapore, Singapore
  2. 2 Myopia Research Group, Singapore Eye Research Institute, Singapore
  3. 3 Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
  4. 4 Ophthalmology and Visual Sciences Academic Clinical Programme, Duke-NUS Medical School, Singapore
  5. 5 Yong Loo Lin School of Medicine, National University of Singapore, Singapore
  6. 6 Department of Maternal Fetal Medicine, KK Women’s and Children’s Hospital, Singapore
  7. 7 Visual Neuroscience Research Group, Singapore Eye Research Institute, Singapore
  1. Correspondence to Dr Seang-Mei Saw, Singapore Eye Research Institute, The Academia, 20 College Road, Discovery Tower Level 6, Singapore 169856, Singapore; ephssm{at}nus.edu.sg

Abstract

Background/aims To evaluate the association of reported time outdoors and light exposure patterns with myopia among children aged 9 years from the Growing Up in Singapore Towards Healthy Outcomes birth cohort.

Methods We assessed reported time outdoors (min/day), light exposure patterns and outdoor activities of children aged 9 years (n=483) with a questionnaire, the FitSight watch and a 7-day activity diary. Light levels, the duration, timing and frequency of light exposure were assessed. Cycloplegic spherical equivalent (SE), myopia (SE≤−0.5 D) and axial length (AL) of paired eyes were analysed using generalised estimating equations.

Results In this study, 483 (966 eyes) multiethnic children (50.0% boys, 59.8% Chinese, 42.2% myopic) were included. Reported time outdoors (mean±SD) was 100±93 min/day, and average light levels were 458±228 lux. Of the total duration children spent at light levels of ≥1000 lux (37±19 min/day), 76% were spent below 5000 lux. Peak light exposure occurred at mid-day. Children had 1.7±1.0 light exposure episodes/day. Common outdoor activities were walks, neighbourhood play and swimming. Greater reported time outdoors was associated with lower odds of myopia (OR=0.82, 95% CI 0.70 to 0.95/hour increase daily; p=0.009). Light levels, timing and frequency of light exposures were not associated with myopia, SE or AL (p>0.05).

Conclusion Reported time outdoors, light levels and number of light exposure episodes were low among Singaporean children aged 9 years. Reported time outdoors was protective against myopia but not light levels or specific light measures. A multipronged approach to increase time outdoors is recommended in the combat against the myopia epidemic.

  • epidemiology
  • public health
  • child health (paediatrics)
  • vision

Data availability statement

The data that support the findings of this study are generated from the Growing Up in Singapore Towards healthy Outcomes (GUSTO) study, but restrictions apply to the public availability of these data, due to ethical restriction (patient confidentiality) imposed by the Singhealth Centralised Institutional Review Board. Datasets are, however, available from the authors upon reasonable request and with the permission of the GUSTO study.

https://doi.org/10.1136/bjophthalmol-2021-318918

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    Data availability statement

    The data that support the findings of this study are generated from the Growing Up in Singapore Towards healthy Outcomes (GUSTO) study, but restrictions apply to the public availability of these data, due to ethical restriction (patient confidentiality) imposed by the Singhealth Centralised Institutional Review Board. Datasets are, however, available from the authors upon reasonable request and with the permission of the GUSTO study.

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    Footnotes

    • Twitter @Ray_Najjar

    • Contributors ML was involved in data collection, statistical analysis, data interpretation, drafting, revision and review of the manuscript. CL served as the study coordinator and was involved in data collection, data interpretation, revision and review of the manuscript. ML and CL contributed equally to this manuscript and are joint first authors and guarantors. C-ST provided statistical advice and was involved in data interpretation, revision and review of the manuscript. L-LF was involved in data interpretation, revision and review of the manuscript. C-HS and FY served as site coordinators, advised on clinical aspects of the study, and were involved in patient recruitment, revision and review of the manuscript. RPN was involved in data interpretation, revision and review of the manuscript. CS was involved in data interpretation, revision and review of the manuscript. S-MS conceived, designed, served as the principal investigator and guarantor of the study. She was involved in data interpretation, revision and review of the manuscript.

    • Funding This study was supported by the Agency for Science Technology and Research, Singapore (A*STAR) and JANSSEN World Without Disease Grant (grant JRBMRR151701).

    • Competing interests None declared.

    • Provenance and peer review Not commissioned; externally peer reviewed.

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