April 15, 2025
By Dwight Akerman, OD, MBA, FAAO, Dipl AAO, FBCLA, FIACLE
Photo Credit: Dreamstime Photos
The systematic review and dose-response meta-analysis (DRMA) conducted by Ha et al. (2025) investigates the relationship between digital screen time and the prevalence of myopia through a systematic review and dose-response meta-analysis. The authors aimed to quantify the risk associated with increased screen time and its impact on myopia development.
The researchers performed a comprehensive literature search to identify relevant studies that examined the association between screen time and myopia. They included studies that provided data on screen exposure and myopia prevalence or incidence. The meta-analysis incorporated data from multiple studies, allowing the authors to calculate pooled odds ratios (ORs) and assess the dose-response relationship.
The findings revealed a positive association between digital screen time and myopia. Specifically, the meta-analysis demonstrated that each additional hour of daily screen time increased the risk of myopia. The dose-response curve indicated a significant rise in myopia prevalence with higher screen exposure. The pooled ORs suggested that children and adolescents who spent more time on digital screens were more likely to develop myopia than those with less screen exposure.
The study also highlighted the variability in risk estimates across different age groups and types of screen devices. For instance, younger children and those using handheld devices showed a higher risk of myopia than older adolescents and those using computers or televisions. The authors emphasized the importance of considering these factors when assessing the impact of screen time on myopia.
Furthermore, the meta-analysis identified several confounding factors that could influence the association between screen time and myopia. These factors included age, sex, socioeconomic status, parental myopia, and outdoor activity levels. The authors adjusted for these variables in their analysis to ensure the robustness of their findings.
Study Limitations
The study has limitations. First, some studies did not use objective measures to assess myopia. In addition, the authors did not analyze long-term fluctuations or temporal variations in digital screen time because most primary studies lacked repeated measurements. Future researchers need to use objective, serial assessments of digital screen time and myopia to establish a more detailed dose-response pattern.
Second, while most of the analyzed studies accounted for confounding factors associated with myopia risk, they handled covariates differently. Several risk factors influence myopia, including a combination of genetic, environmental, and lifestyle factors. Screen time falls into the latter category and potentially interacts with the others. Therefore, the magnitude and pattern connecting screen time and myopia may vary depending on which factors individual studies adjusted.
Third, the authors rated the overall certainty of the evidence at the outcome level as low in their analysis. This downgrade was primarily due to inconsistent results from high heterogeneity, which indicates that the actual effect may differ significantly from the estimated value.
Fourth, most of the studies included in this analysis were cross-sectional. This means that the associations reported cannot allow for the derivation of causal relationships. It is essential to consider the possibility of confounding actors in the association of screen time with myopia. For instance, because screen use predominantly occurs indoors, the resulting reduction in exposure to the protective benefits of outdoor environments may contribute to the increased risk of myopia.
Conclusion
In conclusion, this systematic review and DRMA by Ha et al. (2025) provide evidence of the link between digital screen time and myopia. A daily one-hour increment in digital screen time was associated with 21% higher odds of myopia. The dose-response pattern exhibited a sigmoidal shape, indicating a potential safety threshold of less than one hour per day of exposure, with an increase in odds up to four hours.
Abstract
Digital Screen Time and Myopia: A Systematic Review and Dose-Response Meta-Analysis
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 (i.e., smartphones, tablets, game consoles, computers, or television) with myopia-related outcomes (i.e., 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.
Ha, A., Lee, Y. J., Lee, M., Shim, S. R., & Kim, Y. K. (2025). Digital Screen Time and Myopia: A Systematic Review and Dose-Response Meta-Analysis. JAMA Network Open, 8(2), e2460026-e2460026.
DOI: 10.1001/jamanetworkopen.2024.60026
