Abstract
Purpose: :
Outdoor activity has been reported to be protective against the development of myopia in childhood. Other risk factors including family history and environment have also been proposed. The present study evaluates risk factors for the development of myopia amongst a cohort of Northern Irish children.
Methods: :
The Northern Ireland Childhood Errors of Refraction (NICER) study used stratified random sampling to identify a representative group of children in which to investigate prevalence of refractive error. Initially 399 6-7 year-old and 669 12-13-year-old children were examined. Parental questionnaires were administered; including questions on parental refractive status. Assessment of economic deprivation and urban/rural classification were based on participants’ home address. After 36±3 months participants were invited for repeat examination (aged 9-10 years and 15-16 years) at school. Each participant completed a questionnaire including questions relating to time spent on outdoor activity, visual activity and exercise. Participant refractive errors were determined by cycloplegic autorefraction (1 drop 1% cyclopentolate HCl), axial length measured using the Zeiss IOLMaster and right eye data are presented. Myopia was defined as less than or equal to -0.75 D in each meridian. Risk factors were explored separately for myopia development using univariate logistic regression adjusted for cluster design. A multiple logistic regression model was constructed for those factors showing significant associations under univariate analysis. Odds ratios (OR) with 95% confidence intervals were calculated.
Results: :
Of the original participants 75.7% and 65.2% of the younger and older cohorts respectively were re-examined. In the younger cohort, only lower SER (OR 0.02, CI 0.00 to 0.05) and longer AL (OR 10.88, CI 2.89 to 40.92) at baseline were significant risk factors for myopia development. In the older cohort, whilst lower SER at baseline (OR 0.02, CI 0.00 to 0.11) was a significant risk factor, having two myopic parents (OR 3.49, CI 1.01 to 12.92) was the strongest predictor for future myopia.
Conclusions: :
Our data do not show a protective effect of outdoor activity on myopia development for Northern Irish children. Lower SER at baseline increased the risk of future myopia in the NICER cohort, and having two myopic parents was the most significant risk for developing myopia during teenage years.
Keywords: myopia • refractive error development