A study investigated the use of handheld digital devices and the prevalence of self-reported asthenopia among college students in China using a self-reported questionnaire. The survey recorded the students’ demographic characteristics and habits regarding digital device use.

The prevalence of the eye condition in the cohort of 4,786 students was 53.3%. Multivariate analysis revealed significant relationships between asthenopia and level of digital reliance, workload, the time spent on computer per day, sex and time spent on handheld digital devices in bed and at desk. The study did find that aerobic exercise duration was a strong predictor of fewer asthenopia complaints.

To help reduce and combat eye strain in students, researchers recommend limiting the amount of time spent using digital devices in bed to less than half an hour, adopting a posture of lying on one's back while doing so and also engaging in aerobic exercise for more than one hour per day.