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Digital Screen Time and Myopia: A Systematic Review and Dose-Response Meta-Analysis

Author/s: 
Ahnul Ha, Yun Jeong Lee, Marvin Lee, Sung Ryul Shim, Young Kook Kim

Importance: The association of digital screen time with myopia has been documented, but the dose-response association and safe exposure threshold remain unclear.

Objective: To evaluate the dose-response association of time spent on digital screens with myopia risk.

Data sources: PubMed, EMBASE, Cochrane Library databases, CINAHL, and ClinicalTrials.gov were searched for full-length articles from peer-reviewed journals without restrictions on study design, publication date, or language from inception to November 25, 2024.

Study selection: Primary research articles investigating the association of exposure to digital screen devices (ie, smartphones, tablets, game consoles, computers, or television) with myopia-related outcomes (ie, prevalent or incident myopia and the rate of myopia progression) were identified by reviewers.

Data extraction and synthesis: Two independent reviewers extracted data using a standardized procedure in accordance with the Meta-Analysis of Observational Studies in Epidemiology (MOOSE) and Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) reporting guidelines. A random-effects, dose-response meta-analysis (DRMA) was utilized to examine the pattern of the association of screen time with myopia.

Main outcome and measures: Increased odds of myopia per hour of daily screen time.

Results: In the linear DRMA of 45 studies with 335 524 participants (mean [SD] age, 9.3 [4.3] years), an additional hour of daily screen time was associated with higher odds of myopia (odds ratio [OR], 1.21; 95% CI, 1.13-1.30). The nonlinear DRMA of 34 studies with 314 910 participants also indicated higher odds of myopia with increasing screen time, ranging from 1 hour of daily exposure (OR, 1.05; 95% CI, 1.01-1.09) to 4 hours (OR, 1.97; 95% CI, 1.56-2.40). The dose-response curve showed myopia risk increasing significantly between 1 to 4 hours of daily screen time, and then rising more gradually after 4 hours.

Conclusions and relevance: In this systematic review and DRMA, a daily 1-hour increment in digital screen time was associated with 21% higher odds of myopia and the dose-response pattern exhibited a sigmoidal shape, indicating a potential safety threshold of less than 1 hour per day of exposure, with an increase in odds up to 4 hours. These findings can offer guidance to clinicians and researchers regarding myopia risk.

Keywords 
screen time myopia

Twenty-Four-Hour Movement Guidelines and Body Weight in Youth

Author/s: 
Zhu, X, Healy, S, Haegele, JA, Patterson, F

Objective

To examine the prevalence of youth meeting the 24-hour healthy movement guidelines (ie, ≥60 minutes of moderate-to-vigorous physical activity, ≤2 hours of screen time, age-appropriate sleep duration), and which combination of meeting these guidelines was most associated with bodyweight status, in a nationally representative US sample.

Study design

Cross-sectional data from the 2016-2017 National Survey of Children's Health were used. A multinomial regression model of body weight status was generated (underweight, overweight, obese vs healthy weight) and then stratified by sex. Analyses were adjusted for potential confounders.

Results

The sample (n = 30 478) was 50.4% female, 52.4% white, and the mean age was 13.85 ± 2.28 years; 15% percent were obese and 15.2% were overweight. Overall, 9.4% met all 3 of the 24-hour healthy movement guidelines, 43.6% met 2, 37.9% met 1, and 9.1% met none. Meeting zero guidelines (vs 3) was associated with the greatest likelihood of overweight (aOR, 1.85; 95% CI, 1.31-2.61), and obesity (aOR, 4.25; 95% CI, 2.87-6.31). Females (aOR, 4.97; 95% CI, 2.59-9.53) had higher odds of obesity than males (aOR, 3.99; 95% CI, 2.49-6.40) when zero (vs 3) guidelines were met. Meeting the moderate-to-vigorous physical activity guideline, either alone or in combination with screen time or sleep duration (vs all 3), was associated with the lowest odds for overweight and obesity in the full sample.

Conclusion

Meeting all movement guidelines was associated with the lowest risk for obesity, particularly in females. Meeting the moderate-to-vigorous physical activity guideline may be a priority to prevent overweight and obesity in youth.

Keywords 
24-hour healthy movement screen time sleep physical activity children adolescent
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