Associations of Children's Close Reading Distance and Time Spent Indoors with Myopia, Based on Parental Questionnaire

Purpose: To study the association of parents’ reports about their children’s near work and outdoor habits with myopia in their children. Methods: Data from a questionnaire study conducted in 1983 among Finnish schoolchildren were reanalyzed. Vision screening had been performed for all the schoolchildren (n = 4961) in the 1st, 5th, and 8th grades (7-, 11-, and 15-year-olds) in an area of Central Finland. The questionnaire, including information about myopia, was returned by 4305 (86.7%) participants. Items concerned parents’ estimates of their child’s habitual reading distance, time spent indoors as compared with age peers, daily near work, outdoors time, and parents’ myopia. The associations of myopia with these factors were studied. Results: Myopia prevalence in those with a habitual close reading distance vs. others was 14.3% vs. 2.1%, 28.7% vs. 13.1% and 45.8% vs. 24.7% for the 7-, 11- and 15-year-olds (p < 0.001 in all age-groups). Myopia prevalence in children reported by their parents as spending more time indoors than age peers was 10.9% vs. 2.8% (p < 0.001), 25.0% vs. 14.7% (p = 0.004) and 41.9% vs. 25.7% (p < 0.001) in the three age groups. Myopia prevalence among those reported as spending both more time indoors and reading at a close distance vs. others was 44.2% vs. 11.9% (Fisher’s exact t-test, p < 0.001). In the multiple logistic regression models, parental myopia almost doubled the risk of myopia in the 11- and 15-year-olds. ORs (95% CI) for myopia adjusted for parental myopia and sex were for close reading distance 7.381 (4.054−13.440), 2.382 (1.666−3.406), 2.237 (1.498−3.057), (p < 0.001), and for more time spent indoors, 3.692 (1.714−7.954), p = 0.001, 1.861 (1.157−2.992), p = 0.010), 1.700 (1.105−2.615), p = 0.016, in the three age groups. Conclusion: Children, especially 7-year-olds, reported by their parents as having a close reading distance and spending a lot of time indoors were associated with a higher risk for myopia.

Associations of near work time, watching TV, outdoors time, and parents' myopia with myopia among school children based on 38-year-old historical data

PURPOSE

To study the prevalence and risk factors of myopia with data from a questionnaire study conducted in 1983 among Finnish school children.

METHODS

School children (n = 4 961) from the 1st, 5th and 8th grades of school (7-, 11- and 15-year-olds) in Central Finland were screened for vision followed by a questionnaire, which was returned by 4 352 (87.7%) participants. Myopia was categorized based on the questionnaire. Items concerned daily time spent on near work and outdoor activities, excluding time spent at school, watching TV and parental myopia and the associations of myopia with these factors were studied.

RESULTS

The prevalence of myopia was 3%, 15% and 27% among the 7-, 11- and 15-year-olds, and if daily near work at home was ≤1 hr, myopia prevalence was 0.5%, 3.3% and 17.6%, respectively. The adjusted risk of myopia for each daily near work hour was OR 1.476 (95% confidence interval 1.099-1.984, p = 0.010), OR 1.346 (1.170-1.584, p < 0.001) and OR 1.206 (1.076-1.352, p = 0.001), in the 3 age groups, respectively. The adjusted risk of myopia for each daily hour spent outdoors was OR 0.764 (0.648-0.900, p = 0.001) in the 11-year-olds and OR (0.840, 0.743-0.950, p = 0.005) in the 15-year-olds. Outdoors time prevented myopia at different levels of near work, although less at the highest levels, and near work increased risk of myopia with the level of outdoors time. If the ratio between near work and outdoors time was ≤0. 5 or >1.5, the prevalence of myopia was 1.4% versus 5.6%, 6.3% versus 24.7% and 15.9% versus 36.9%, among the 7-, 11- and 15-year-olds, respectively. The higher prevalence of myopia among the 11- and 15-year-old girls than boys was explained by more near work and less outdoor time among the girls. Having two myopic parents roughly doubled the risk of myopia compared to if one myopic parent in the 11- and 15-year-olds.

CONCLUSIONS

Myopic parents, greater near work time, less outdoors time, a higher near work/outdoors ratio, and being a girl increased the risk of myopia. Myopia was rare in the 7- and 11-year-olds if daily near work at home did not exceed one hour or if the near work/outdoors ratio was not higher than 0.5. Outdoors time was associated with the prevalence of myopia at all levels of near work, although the association was weaker at the highest level.