Combination Effect of Outdoor Activity and Screen Exposure on Risk of Preschool Myopia: Findings From Longhua Child Cohort Study

Abstract

Evidence regarding screen use and outdoor activity during very early childhood (i. e., from aged 1 to 3 years) and their potential combined links to the later preschool myopia is limited. This information is needed to release effective public health messages and propose intervention strategies against preschool myopia. We collected information regarding very early childhood screen use, outdoor activity and the kindergartens vision screenings of 26,611 preschoolers from Longhua Child Cohort Study by questionnaires. Logistic regression models were used to examine the associations between reported outdoor activity, screen use from 1 to 3 years of age, and preschool myopia. Throughout very early childhood, from 1 to 3 years, the proportion of children exposed to screens increased (from 35.8 to 68.4%, p < 0.001), whereas the proportion of children who went outdoors ≥7 times/week (67.4-62.1%, p < 0.001) and who went outdoors for ≥60 min/time (53.3-38.0%, p < 0.001) declined. Exposure to fixed screen devices [adjusted odds ratio (AOR) = 2.66, 95% confidence interval (CI) = 2.09-3.44], mobile screen devices (AOR = 2.76, 95% CI = 2.15-3.58), and limited outdoor activity (AOR = 1.87, 95% CI = 1.42-2.51) during early childhood were associated with preschool myopia. Among children whose parents were myopic, the interactions between outdoor activity and fixed or mobile screen use on later preschool myopia were significant; the ORs and 95% CI were 3.34 (1.19-9.98) and 3.04 (1.06-9.21), respectively. Our findings suggest the possibility that the impact of screen exposure during early childhood on preschool myopia could be diminished by outdoor activity for children whose parents have myopia.

Keywords: early childhood; interaction; myopia; outdoor activity; screen use.

Figure 1

Yearly outdoor activity and screen use from 1 to 3 years of age. During the first 3 years after birth, the proportion of children who went outdoors for ≥7 times/week declined, from 67.4% at age 1 year to 62.1% at age 3 years, as did the proportion of children who spent ≥60 min outdoors, from 53.3% at age 1 year to 37.4% at age 3 years. In contrast, the proportion of children exposed to fixed screen devices increased from 17.7% at age 1 year to 55.3% at age 3 years, and the proportion of children exposed to handheld mobile devices went from 18.6% at age 1 year to 40.2% at age 3 years.

Figure 2

The combined effect of fixed screen use and outdoor activity from 1 to 3 years of age on preschool myopia. (A–C) Present the combined effects of frequency, duration of outdoor activity, the overall outdoor factors, and screen use on myopia after adjusting for children's age, gender, maternal age at childbirth, monthly household income, and parental history of myopia. Compared with children who had not been exposed to screens and had a high level of outdoor activity, children who were reported to have exposure to fixed screen devices and a low frequency of outdoor activity had an increased prevalence of myopia. **p < 0.01, ***p < 0.001.

Figure 3

The combined effect of mobile screen use and outdoor activity from 1 to 3 years of age on preschool myopia. (A–C) Present the combined effects of frequency, duration of outdoor activity, the overall outdoor factors, and screen use on myopia after adjusting for children's age, gender, maternal age at childbirth, monthly household income, and parental history of myopia. Compared with children who had not been exposed to screens and had a high level of outdoor activity, children who were reported to have exposure to mobile screen devices and a low frequency of outdoor activity had an increased prevalence of myopia. ^*p < 0.05, ^**p < 0.01, ^***p < 0.001.