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Myopia in school-aged children with preterm birth: the roles of time spent outdoors and serum vitamin D
  1. Hung-Da Chou1,2,
  2. Tsung-Chieh Yao2,3,
  3. Yu-Shu Huang2,4,
  4. Chung-Ying Huang1,2,
  5. Men-Ling Yang1,2,
  6. Ming-Hui Sun1,2,
  7. Hung-Chi Chen1,2,
  8. Chun-Hsiu Liu1,2,
  9. Shih-Ming Chu2,3,
  10. Jen-Fu Hsu2,3,
  11. Kuan-Jen Chen1,2,
  12. Yih-Shiou Hwang1,2,
  13. Chi-Chun Lai1,2,
  14. Wei-Chi Wu1,2
  1. 1 Department of Ophthalmology, Chang Gung Memorial Hospital, Linkou Medical Center, Taoyuan, Taiwan
  2. 2 College of Medicine, Chang Gung University, Taoyuan, Taiwan
  3. 3 Department of Pediatrics, Chang Gung Memorial Hospital, Linkou Medical Center, Taoyuan, Taiwan
  4. 4 Department of Child Psychiatry and Sleep Center, Chang Gung Memorial Hospital, Linkou Medical Center, Taoyuan, Taiwan
  1. Correspondence to Professor Wei-Chi Wu, Department of Ophthalmology, Chang Gung Memorial Hospital, Linkou, No. 5 Fu-Hsing Street, Kwei-Shan 333, Taoyuan, Taiwan; weichi666{at}


Aims To analyse the factors associated with myopia in school-aged children with preterm birth and with or without retinopathy of prematurity (ROP).

Methods Children born prematurely between January 2010 and December 2011 were enrolled in this cross-sectional study when they reached school age between April 2017 and June 2018 in a referral centre. The main parameters were cycloplegic refraction, time spent outdoors and serum 25-hydroxyvitamin D (25(OH)D) concentration.

Results A total of 99 eyes from 99 children with a mean age of 6.8 years underwent analysis. The average time spent outdoors was significantly higher in the non-myopic group (0.9 ± 0.5 hours/day) than in the myopic group (0.7 ± 0.3 hours/day) (p = 0.032). After adjustment for age, sex, number of myopic parents, ROP severity, near-work time and serum 25(OH)D concentration, more time spent outdoors was correlated with a lower odds of myopia (OR, 0.13 per additional hour per day; 95% CI, 0.02–0.98; p = 0.048). Mean serum 25(OH)D concentrations were similar between the myopic and non-myopic groups (49.7 ± 13.6 and 48.8 ± 14.0 nmol/mL; p = 0.806) and were not correlated with spherical equivalence power (r = −0.09; p = 0.418). Vitamin D insufficiency was present in 57% of the participants.

Conclusions Among preterm children with or without ROP, more time spent outdoors was associated with lower odds of myopia. The serum 25(OH)D concentration was not associated with myopia, but a high proportion of the participants had insufficient levels.

  • child health (paediatrics)
  • optics and refraction
  • public health
  • retina
  • vision

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  • Contributors Chou HD drafted the manuscript and organised the data for analysis. Yao TC, Huang YS and Wu WC provided the idea of the study. Yao TC, Huang YS, Huang CY, Lai CC and Wu WC planned the study and obtained grants. Huang CY, Yang ML, Sun MH, Chen HC, Liu CH, Chu SM, Hsu JF, Chen KJ, Hwang YS and Wu WC conducted the study. Wu WC revised the manuscript and reviewed the article. All authors read and approved the final manuscript.

  • Funding This study was supported by research grants from Chang Gung Memorial Hospital (CMRPG3I0071-3 and CMRPG3G0581-3) and a Ministry of Science and Technology Research Grant (MOST 106-2314-B-182A-040-MY3).

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Ethics approval The study was approved by the Institutional Review Board (201 601 156A3) and adhered to the tenets of the Declaration of Helsinki.

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

  • Data availability statement Data are available upon reasonable request.

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