In the news: Screen Time & Myopia: Guidance; Vitamin D Protects Telomeres

Does Digital Screen Time Lead to a Future of Blurry Vision for Children?

Most vision care professionals are aware that the prevalence of myopia or nearsightedness has been steadily rising over the past decade or so. Myopia prevalence was approximately 28% in 2010, and it is projected to reach 50% by 2050.

The link between digital screen time and myopia has been previously documented. What has not been clear is whether this association is dose-dependent and whether a safe viewing time threshold exists.

To provide more information, researchers conducted a meta-analysis of over 45 studies that investigated exposure to digital screen devices (smart-phones, tablets, game consoles, computers or TV) with prevalent or incident myopia and the rate of myopia progression(1). The analysis included over 335,000 participants (mostly children, average age of nine).

The study found that every one hour of daily screen time is associated with 21% higher odds of myopia. The risk increases from 1 to 4 hours of screen time daily, then rises more gradually with additional hours of use.

The results also showed that the risk of near-sightedness doubles for those spending four or more hours daily in total device screen time.

The investigators noted that the odds of myopia and screen time was evaluated independently of other close work activities such as reading or writing – activities that have also been linked to myopia risk.

However, it’s likely that screen time and other near-vision tasks collectively contribute to risk, according to the authors, who suggest minimizing over all up- close activities and promoting more time outdoors.

This study offers an up-to-date and comprehensive analysis of the relationship between screen time and myopia. The findings suggest that limited device use of up to an hour daily isn’t likely to pose any real risk for nearsightedness.

VITAL Findings: Vitamin D Protects Telomeres

According to recent results from an analysis of the VITAL study, supplementation with vitamin D plays a promising role in protecting telomeres and slowing their shortening(2,3).

Telomeres are specialized chromatin structures or caps found at the end of chromosomes where they function to help maintain the stability and integrity of the chromosomes when cells divide. Telomeres shorten with each cell division, and this shortening is linked to aging and disease development. Those with very short telomeres are more likely to have age-related conditions such as CVD, cancer and premature mortality.

The researchers assessed the relationship between supplemental vitamin D and telomeres because previous VITAL results showed a reduced risk for advanced and metastatic cancers and autoimmune conditions, as well as reduced inflammatory biomarkers. (For an overview of Harvard’s randomized Vitamin D and Omega-3 Trial or VITAL, see EduFacts Vol. 21, sbh.com)

Participants had blood collections at baseline, 2 years and 4 years; telomere length was measured by quantitative PCR. Results showed a substantial shortening in the placebo group versus minimal shortening in the vitamin D over the 4 years of intervention, with a significant difference between the two groups (p = 0.037).

The authors estimate that this between group difference is roughly equivalent to a 3 year decrease in aging, based on longitudinal studies that have looked at the amount of telomere loss with aging.

References

1. Ha A, et al. Digital screen time and myopia: A systematic review and dose-response meta-analysis. JAMA Netw Open. 8(2)e2460026, 2025.
2. Zhou H, et al. Vitamin D3 and marine ω-3 fatty acids supplementation and leukocyte telomere length: 4-year findings from the VITamin D and OmegA-3 TriaL (VITAL) randomized controlled trial. Am J Clin Nutr Published online May 21, 2025.
3. Manson J. Vitamin D supplementation protects telomeres in VITAL Medscape, May 21, 2025.