Elsevier

Ophthalmology

Volume 115, Issue 8, August 2008, Pages 1279-1285
Ophthalmology

Original article
Outdoor Activity Reduces the Prevalence of Myopia in Children

https://doi.org/10.1016/j.ophtha.2007.12.019Get rights and content

Objective

To assess the relationship of near, midworking distance, and outdoor activities with prevalence of myopia in school-aged children.

Design

Cross-sectional study of 2 age samples from 51 Sydney schools, selected using a random cluster design.

Participants

One thousand seven hundred sixty-five 6-year-olds (year 1) and 2367 12-year-olds (year 7) participated in the Sydney Myopia Study from 2003 to 2005.

Methods

Children had a comprehensive eye examination, including cycloplegic refraction. Parents and children completed detailed questionnaires on activity.

Main Outcome Measures

Myopia prevalence and mean spherical equivalent (SE) in relation to patterns of near, midworking distance, and outdoor activities. Myopia was defined as SE refraction ≤−0.5 diopters (D).

Results

Higher levels of outdoor activity (sport and leisure activities) were associated with more hyperopic refractions and lower myopia prevalence in the 12-year-old students. Students who combined high levels of near work with low levels of outdoor activity had the least hyperopic mean refraction (+0.27 D; 95% confidence interval [CI], 0.02–0.52), whereas students who combined low levels of near work with high levels of outdoor activity had the most hyperopic mean refraction (+0.56 D; 95% CI, 0.38–0.75). Significant protective associations with increased outdoor activity were seen for the lowest (P = 0.04) and middle (P = 0.02) tertiles of near-work activity. The lowest odds ratios for myopia, after adjusting for confounders, were found in groups reporting the highest levels of outdoor activity. There were no associations between indoor sport and myopia. No consistent associations between refraction and measures of activity were seen in the 6-year-old sample.

Conclusions

Higher levels of total time spent outdoors, rather than sport per se, were associated with less myopia and a more hyperopic mean refraction, after adjusting for near work, parental myopia, and ethnicity.

Section snippets

Materials and Methods

The Sydney Myopia Study is a population-based survey of refraction and other eye conditions in a sample of year 1 and year 7 school children resident in the metropolitan area of Sydney, Australia. Methods used to identify and select the target sample, as well as a description of this sample and study procedures, are reported elsewhere.28, 30 In brief, the study area was stratified by socioeconomic status, using Australian Bureau of Statistics 1996 and 2001 national census data. Using this

Results

Of the 2238 eligible children in year 1, 1765 (78.9%) were given parental permission to participate and 1740 were examined. Of the 3130 eligible children in year 7, 2367 (75.3%) were given permission and 2353 were examined (Table 1). Mean ages were 6.7 years (year 1 participants; range, 5.5–8.4) and 12.7 (year 7 participants; range, 11.1–14.4). Girls comprised just under half of each sample (49.4% in year 1 and 49.4% in year 7). Ethnicity of the year 1 sample was predominantly European

Discussion

Although some previous studies have reported an association between refractive error and more time spent on sport or outdoor activities, this population-based study is the first to make separate detailed measurements of time spent on outdoor activities and engagement in near work and indoor activities, which enable a discrimination between the effects of near work, middistance, and distance activities, as well as the effects of time spent on sport and total time spent outdoors.

Parssinen and

References (38)

  • R. Lim et al.

    Refractive associations with cataract: the Blue Mountains Eye Study

    Invest Ophthalmol Vis Sci

    (1999)
  • T.Y. Wong et al.

    Refractive errors and incident cataracts: the Beaver Dam Eye Study

    Invest Ophthalmol Vis Sci

    (2001)
  • K. Grodum et al.

    Refractive error and glaucoma

    Acta Ophthalmol Scand

    (2001)
  • M.T. Tay et al.

    Myopia and educational attainment in 421,116 young Singaporean males

    Ann Acad Med Singapore

    (1992)
  • M.M. Wu et al.

    The effect of having myopic parents: an analysis of myopia in three generations

    Optom Vis Sci

    (1999)
  • L.L. Lin et al.

    Changes in ocular refraction and its components among medical students—a 5-year longitudinal study

    Optom Vis Sci

    (1996)
  • W.W. Woo et al.

    Refractive errors in medical students in Singapore

    Singapore Med J

    (2004)
  • L.L. Lin et al.

    Prevalence of myopia in Taiwanese schoolchildren: 1983 to 2000

    Ann Acad Med Singapore

    (2004)
  • S.M. Saw et al.

    Myopia and associated pathological complications

    Ophthalmic Physiol Opt

    (2005)
  • Cited by (932)

    • The challenges of the myopia pandemic

      2024, Bulletin de l'Academie Nationale de Medecine
    • The influence of the environment and lifestyle on myopia

      2024, Journal of Physiological Anthropology
    View all citing articles on Scopus

    Manuscript no. 2007-1147.

    No conflicting relationship exists for any author.

    The Sydney Myopia Study is supported by the National Health & Medical Research Council, Canberra, Australia (grant no. 253732), and Westmead Millennium Institute, University of Sydney, Sydney, Australia. Dr Morgan's contribution was supported by the Australian Research Council, Canberra, Australia (grant no. COE561903). The sponsors and funding organizations had no role in the design or conduct of the research.

    View full text