Myopia prevalence in Canadian school children: A pilot study

TitleMyopia prevalence in Canadian school children: A pilot study
Publication TypeJournal Article
Year of Publication2018
AuthorsYang, M., D. Luensmann, D. Fonn, J. Woods, D. Jones, K. Gordon, and L. Jones
JournalEye (Basingstoke)
Keywordsaccommodation paralysis, adolescent, Article, axial length, biometry, Canada, Canadian, child, clinical assessment, Cross-Sectional Studies, cross-sectional study, daily life activity, environmental factor, Eye, eye axis length, eye refraction, female, groups by age, human, Humans, Logistic Models, major clinical study, male, myopia, outcome assessment, Pilot Projects, pilot study, Prevalence, questionnaire, school child, statistical model
AbstractPurpose: A pilot study to determine the prevalence of myopia, proportion of uncorrected myopia and pertinent environmental factors among children in a suburban region in Canada. Methods: Refraction with cycloplegia and ocular biometry were measured in children of two age groups. Myopia was considered at a spherical equivalent refraction (SER) ≤-0.50 D in at least one eye. Parents completed a questionnaire that captured the child's daily activities. Results: A total of 166 children completed the study (83 aged 6-8 and 83 aged 11-13). Myopia prevalence was 17.5% among the overall group, 6.0% among ages 6-8 and 28.9% among ages 11-13. Mean subjective SER in myopic children was -1.10 D (95% confidence interval (CI), -0.34 to -1.86 D) at ages 6-8 and -2.44 D (95% CI, -1.71 to -3.18 D) at ages 11-13. In this study, 34.5% of the myopic children were uncorrected, which represented 6.0% of the entire group of children. Mean axial length (AL) increased by 1.03 mm from ages 6-8 (mean 22.62 mm; 95% CI, 22.45 to 22.79 mm) to ages 11-13 (mean 23.65 mm; 95% CI, 23.45 to 23.84 mm; p < 0.01). The correlation coefficient between AL and SER was -0.618 (p < 0.01). Binary logistic regression between outdoor time and the prevalence of myopia showed that one additional hour of outdoor time per week lowered the odds of a child having myopia by 14.3% (p = 0.007). Conclusion: Myopia prevalence increased from 6% at ages 6-8 to 29% at ages 11-13. Thirty-five per cent of the myopes in this study were uncorrected. More time outdoors may be beneficial to protect against myopia onset. © 2018 The Royal College of Ophthalmologists.