Gazing at smartphone screens for even one hour a day can cause digital eye strain, especially when scrolling through social media. According to a new study published in the Journal of Eye Movement Research, it is not just the time spent on digital devices but also the type of content being used that can cause the condition.

Smartphone use has surged across the world in recent years, with around 90% of mobile phone users having one. As people spend several hours a day on their devices, there is a growing concern for their vision and eye health. Digital eye strain is a group of vision-related problems that can cause symptoms like blurred vision, double vision and eye tearing.

Studying the risks

To better understand the prevalence and risks of prolonged screen use, scientists studied 30 young adults in India, where smartphone use is particularly high. The researchers developed a portable eye-monitoring system using a Raspberry Pi and an IR camera to track real-time measures of eye strain, such as blink rate, pupil diameter and inter-blink intervals.

Researchers conducted the experiment over several days. Each participant used a Realme 6 Pro smartphone for one-hour sessions of reading e-books, watching videos and scrolling through social media reels. They were seated in a non-adjustable office chair with the phone at a fixed distance.

Pupil size variations: (a) larger and (b) smaller.

An analysis of the data revealed that scrolling through social media reels caused the most eye strain. Pupil dilation fluctuated more when reading social media compared to reading e-books or watching videos.

"The constant changes in content and brightness during social media browsing lead to more significant eye strain," the researchers wrote in their paper.

The study also found a significant decrease in blink rate (by 54–61%) over one hour of smartphone use and an increase in the inter-blink interval (39–42%), which means eyes stay open for longer. A decrease in the blink rate and an increase in the inter-blink interval are both indicators of visual fatigue.

This study highlights the risk of everyday smartphone use. While most previous studies measured eye fatigue for brief periods of three to 15 minutes, which does not reflect real-world usage, this research looked at longer durations.

Although one hour is still shorter than the time many people spend on their devices, the findings can be used to inform public health initiatives that encourage people to protect their eye health, for example, by minimizing social media use on smartphones.

As screen time increases, the need for solutions to protect eye health has never been greater. The study's authors believe their system can help address this issue. As they note in their paper, "Our portable system offers a cost-effective way to monitor and address this growing health concern."

More information: Bhanu Priya Dandumahanti et al, Digital Eye Strain Monitoring for One-Hour Smartphone Engagement Through Eye Activity Measurement System, Journal of Eye Movement Research (2025). DOI: 10.3390/jemr18040034