Strong Association Between Smartphone Use and Myopia, According to New Study

According to a study presented at the 2025 American Optometric Association Conference in Minneapolis, MN, increased weekly smartphone use may increase myopia risk due to cumulative near-work exposure.1

Widespread acceptance of screens for diverse purposes has led to noticeable reductions in cardiovascular, mental, and ocular health across the population. The COVID-19 pandemic brought about a substantial increase in screen exposure and time indoors worldwide, both of which investigators have previously indicated as being associated with rising rates of myopia.2

To that end, Alvin Munsamy, PhD, associate professor at the University of KwaZulu-Natal, and colleagues conducted a cross-sectional, observational study sampling university students to investigate myopia incidence in young adults. To be included, patients had to be smartphone users between 18 and 30 years old with no ocular diseases. Exclusion criteria included best corrected distance of 6/6, near visual acuity (VA) poorer than 1M, and no mobile screen time application.1

A total of 232 patients were randomly recruited to participate in the study; the mean (Standard Deviation [SD]) participant age was 20 years +/- 2 years, and the group was 74.6% female. Investigators collected each participant’s objective mobile screen time measurements and dry autorefraction and biometry.1

Participants had a mean (SD) spherical equivalent of -1.03 +/- 2.19 and a mean axial length of 23.39mm +/- .87. Daily mobile device screen exposure averaged out to 447.86 minutes +/- 149.43, while weekly exposure measured at 2047.98 minutes +/- 1044.97.1

Upon analysis, investigators noted a significant relationship between higher mobile device screen exposure and axial length. Daily exposure was associated with an odds ratio (OR) of 1.21 (95% CI, 1.14 to 1.28; P <.001), while weekly exposure was associated with a 1.24 OR (95% CI, 1.17 to 1.31; P <.001). These data suggested a direct relationship between screen exposure and axial length, with more exposure resulting in higher axial length.1

Munsamy and colleagues indicated higher weekly mobile device screen time as a greater risk than daily, due in large part to cumulative near-work exposure. Additionally, prolonged screen use increases sustained accommodation, which contributes to axial elongation. The team also noted a significant reduction in recall bias risk by using objective screen time measurement.1

According to investigators, prior research largely focused on children and utilized subjective screen time assessment; both issues were avoided in this study. However, the team also noted a few limitations, including the study group’s skewing towards female participants. They stated this may impact the generalizability of findings. Additionally, screen time from non-mobile devices was not included in the study.1

Ultimately, the team suggests objective measurement across all electronic devices in future studies to strengthen findings, given the cumulative nature of screen exposure. Additionally, longitudinal studies are necessary to evaluate causality. Notably, investigators also strongly recommend a screen time threshold linked to axial elongation, which would inform guidelines for safe device usage.1

“Promoting responsible digital device use is essential to protect long-term ocular health in today’s digital environment,” Munsamy and colleagues wrote.1

References

1. Munsamy AJ, Beekuram R, Dawood F, et al. The Impact of Screen Time on Axial Length in Smartphone Users. Abstract presented at the 2025 American Optometric Association Conference in Minneapolis, MN, June 25-28, 2025.

2. Hoff JM, Midelfart A. COVID-19 and myopia. Koronamyopi. Tidsskr Nor Laegeforen. 2021;141(9):10.4045/tidsskr.21.0336. Published 2021 May 27. doi:10.4045/tidsskr.21.0336