Optometrists are seeing more reports of visual discomfort associated with screen exposure, but a new study published in Optometry and Vision Science (Cognitive demand, concurrent viewing distances, and digital eyestrain, April 2025) reveals that the problem extends beyond simply screen time. It suggests that cognitive workload and task-related viewing behavior play a more prominent role in visual fatigue than previously understood. Let’s take a look.
Study summary
Study authors Elianna Sharvit, OD, MS, and Mark Rosenfield, PhD, FAAO, investigated how cognitive demand and viewing conditions affect symptoms of eye strain. Participants performed reading tasks under both low and high cognitive load, using either a screen or printed material.
Key findings
- Higher cognitive demand led to a significant increase in reported visual fatigue symptoms. Tasks that required more mental effort produced more discomfort, regardless of whether the material was presented on paper or a screen.
- While participants’ working distance decreased during both screen and paper tasks, this change in viewing distance did not significantly affect symptoms. In other words, how close the material was to the eyes wasn’t the main issue.
- Mode of presentation — paper versus digital — did influence symptoms slightly, but not as much as cognitive load. This suggests that visual fatigue may have less to do with screens themselves and more to do with the nature of the task and how mentally demanding it is.
- The study emphasized that cognitive factors had the clearest and most consistent impact on discomfort.
Academic insight from SUNY
A full thesis by Sharvit, available via the SUNY College of Optometry expands on the methods and psychometric analysis used. It offers a deeper look at how subjective symptoms align with objective changes in accommodation and blink behavior, further supporting the link between mental effort and visual strain.
Implications for optometric care
This research supports ODs looking beyond device use and considering how task complexity and visual behavior patterns may contribute to symptoms of digital eye strain:
- Ask patients if they frequently juggle demanding tasks or work that requires sustained concentration. Patients may not otherwise think to mention how often they do so.
- Review a patient’s work and study environments. Encourage strategies that reduce visual complexity, like minimizing back-and-forth between devices.
- Educate patients that visual fatigue can stem from cognitive stress and visual task switching, not just prolonged screen exposure.
The study also suggests “objective testing of visual function (such as accommodative lag and ocular alignment), as well as assessment of the anterior surface of the eye and tear film, both during and after the task, could be used to determine whether the symptoms are truly visual in origin or rather if the perceived difficulty of the task is related to the development of symptoms on a psychological basis.” (Source: Working distance on paper vs. screen not a factor in eyestrain in study)
Overall, you might begin to reconsider how you think about digital eye strain. Rather than focusing solely on screen usage, investigate visual fatigue through a broader lens that includes mental workload and viewing dynamics.
