Adverse effects of excessive screen time can include computer vision syndrome, myopia, reduced sleep quality and reduced cognitive, social and linguistic skills. However, this study found improved color vision in boys, possible due to retinal stimulation from blue light. Photo: Getty Images. Click image to enlarge.

The necessity of digital technology in today’s world makes it difficult to avoid electronic screens. To curb the rise in childhood myopia, limiting screen time has been recommended. However, children may still be vulnerable to the effects of digital screens even small amounts. How much is too much? Recently, researchers evaluated the effects of moderate screen exposure at an early age and later visual function and found no harmful effects on visual function development.

The researchers examined broader aspects of visual function under normal viewing conditions such as color discrimination, contrast sensitivity and short-range visual acuity in 12-year-old children (n=305) from a sex-stratified French cohort. Screen exposure (video games and TV- and video-watching) data was obtained through parent self-reported questionnaire.

The researchers reported that screen exposure at six years of age was significantly associated with higher contrast sensitivity across all children at age 12 on regression models. After adjusting for covariates, this association was significant for only girls. Improved contrast sensitivity from playing video games has previously been documented. “This enhancement of the visual function is thought to rely on the brain’s capacity to adapt and reorganize neural pathways following extensive visual experience,” the researchers explained in their Vision paper, adding that action video games in particular seem to have this effect.

A novel finding of the study was improved tritan-axis color vision in boys, which may be due to retinal stimulation from blue light. “Moderate exposure to blue light from digital screens could have a greater impact on the tritan axis (compared to the other axes) due to the higher sensitivity of the corresponding blue-light photoreceptor cells to short-wavelength light (i.e., blue light),” the researchers suggested.

Interestingly, the study found no association between a need for glasses and screen exposure. “Contrary to our initial expectations, our study yielded results that challenge the prevailing belief regarding the detrimental impact of screen exposure on visual function,” the researchers wrote in their paper. “Indeed, our findings not only suggest an absent association between screen exposure and a decrease in the examined visual outcomes but that improvements can be observed in some sex-specific cases. These results diverge from previous studies that primarily focused on refractive errors (e.g., myopia or visual acuity) as the key indicators of visual health.”

They concluded that moderate screen exposure in middle childhood isn’t harmful to visual function development and that these findings may “provide new insights into the impact of digital technology on children’s visual health and development.”