Association between near work, screen time, outdoor time and myopia in children

Objective  To analyze the correlation between near work, screen time, outdoor time and myopia in children based on objective monitoring technology and to explore the influencing factors related to myopia in children.

Methods  A cross-sectional study was conducted.From October 2022 to March 2023, the purposive sampling method was used to select 596 children in Grade 2 and Grade 3 from two primary schools in Shandong Province as study subjects.Eye-Monitor technology of eye-use behavior based on artificial intelligence was used to quantify parameters of near work, screen time and outdoor time.The eye-use behavior parameters were compared within each subject and between non-myopic and myopic children on weekdays and weekends.A multivariate binary logistic regression model was constructed to analyze the influencing factors related to myopia.The study protocol was approved by the Medical Ethics Committee of the Affiliated Eye Hospital of Shandong University of Traditional Chinese Medicine (No.HEC-HY-2022023KY).Written informed consent was obtained from the legal guardian of each subject.

Results  For each subject, the proportion of near work time on weekdays was greater than on weekends, the proportion of time spent looking at cell phones, computer screens, and outdoor activities was smaller, the duration of single continuous near eye use was longer, the tilt angle of the head in sitting position was greater, and the light intensity was stronger, showing statistically significant differences ( t=19.427, -9.964, -5.916, -10.470, 2.211, 2.898, 15.061; all P<0.05).During weekdays, compared with the non-myopia group, the myopia group had longer total near work duration, longer single continuous near eye use duration, shorter outdoor activity duration, closer eye use distance, larger proportion of near work time, and smaller proportion of outdoor activity time, showing statistically significant differences (all P<0.05).During weekends, compared with the non-myopia group, the myopia group had longer time spent looking at cell phones and computer screens, shorter outdoor activity time, greater proportion of time spent looking at cell phones and computer screens, and smaller proportion of outdoor activity time, with statistically significant differences (all P<0.05).During weekdays, after adjusting for confounding factors, longer single continuous near eye use duration ( OR=1.138, 95% CI: 1.086-1.192, P<0.001) was the risk factor for myopia, and longer working distance ( OR=0.906, 95% CI: 0.847-0.970, P=0.004) and longer outdoor activity time ( OR=0.127, 95% CI: 0.023-0.703, P=0.018) were protective factors for myopia.During weekends, after adjusting for confounding factors, longer time spent on looking at cell phone screens ( OR=2.437, 95% CI: 1.460-4.068, P<0.001) and longer time spent on looking at computer screens ( OR=2.260, 95% CI: 1.283-3.979, P=0.005) were risk factors for myopia, and longer outdoor activity time ( OR=0.624, 95% CI: 0.416-0.934, P=0.022) was the protective factor for myopia.

Conclusions  The eyes with continuous near work, prolonged use of smartphone and computer screens, closer eye use distance, and less time spent outdoors have been confirmed to be significantly correlated with myopia based on objective monitoring data.When formulating intervention measures for myopia prevention and control in children, it is advocated to further pay attention to control the distance and duration of near work on weekdays and strengthen screen time management on weekends.

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