Investigators examined the association between digital screen time and myopia in a systematic review and identified a significant dose-response relationship.
In a linear dose-response meta-analysis of 45 studies encompassing 335,524 participants who were a mean age of 9.3 years, they found that each additional hour of daily screen time was associated with a 21% increase in the risk of developing myopia.
In a nonlinear dose-response meta-analysis of data from 34 studies with 314,910 participants, the investigators, led by Ahnul Ha, MD, of the Department of Ophthalmology at the Jeju National University Hospital in Jeju-si, Korea, demonstrated that myopia risk increased significantly between 1 and 4 hours of daily screen exposure, after which the risk rise plateaued, according to the study, published in JAMA Network Open.
For 1 hour of daily screen use, the odds ratio (OR) for myopia was 1.05 (95% confidence interval [CI] = 1.01–1.09). The risk increased to 1.97 (95% CI = 1.56–2.40) at 4 hours. Beyond 4 hours, the risk continued to rise but at a slower rate, forming a sigmoidal curve.
The investigators systematically searched PubMed, EMBASE, Cochrane Library, CINAHL, and ClinicalTrials.gov for full-length peer-reviewed articles published through November 2024. Inclusion criteria focused on studies that explored the association between digital screen use (smartphones, tablets, gaming consoles, computers, and televisions) and myopia-related outcomes (prevalence, incidence, and progression). Data were extracted independently by two reviewers following PRISMA and MOOSE guidelines. Bias assessments were conducted using the Newcastle-Ottawa Scale.
Subgroup analyses were conducted based on age, geographic region, and study design. Sensitivity analyses adjusted for potential confounders, including the use of different screen devices and myopia diagnostic methods.
In addition to the 21% increase in the risk of developing myopia associated with each additional hour of daily screen time (OR = 1.21, 95% CI = 1.13–1.30), the investigators noted from previous research that the risk of myopia increased by 77% when smartphone or tablet use was combined with computer use.
“The widespread adoption of smart devices among children introduces a novel dimension to our understanding and measurement of near-work activities. Global smartphone penetration surged from 21.6% in 2014 to 69.0% in 2023. Additionally, the age at which children begin using smart devices is decreasing, with many 2-year-olds spending up to 2 hours daily on such devices,” the study authors wrote.
They acknowledged several limitations, including heterogeneity among included studies, variability in the assessment of screen time, and reliance on self-reported data in some cases. Most studies analyzed were cross-sectional and limited the ability to establish causality. The overall certainty of evidence was rated as low because of inconsistencies in study methodologies and potential residual confounding factors. The investigators also analyzed the association between myopia and screen time independently of reading, writing, and other near-vision activities.
“It is also likely that digital screen use and other near-vision tasks collectively contribute to myopia risk, potentially influencing the overall dose-response trend. Therefore, caution is warranted when considering the 1-hour daily screen time safety threshold reported here,” the study authors underscored.
They concluded that these results could inform future research, educational strategies, and public health policies regarding myopia intervention.
No conflicting interests were declared.
