What is the recommended viewing distance for digital devices?

By Neha MathurOct 12 2023Reviewed by Lily Ramsey, LLM

In a recent article published in Nature’s Eye Journal, researchers presented the findings of a prospective, cross-sectional study conducted among their coworkers to evaluate how viewing distance from digital devices, such as smartphones and computers, affects binocular vision.

Study: At what distance should digital devices be viewed? Image Credit: fizkes/Shutterstock.com

Background

Studies have evidenced that spending more time working on computers/laptops or viewing smartphones causes asthenopic symptoms, such as fatigue of the eyes accompanied by pain and headache.

About the study

In the present study, researchers hypothesized that closer viewing distance and smaller font size increase the demand for binocular vision, which, in turn, aggravates or worsens asthenopic symptoms.

In other words, looking at digital devices from a short distance (less than 35cm) compromises the focusing mechanism of the eyes that helps produce a sharp image on the retina (accommodation) and the ability to fixate on objects and perceive them as single (vergence).

To test their hypothesis, the researchers recruited 114 (72 females) 19–50-year-old participants, with an average age of 26±6, who provided written consent and readily filled a modified convergence insufficiency symptoms survey.

The total scores of this survey ranged between zero and 39, where zero and 39 indicated that a participant was asymptomatic and highly symptomatic, respectively.

Since the researchers wanted to capture the effects of two study parameters on real-world work settings, they measured viewing distance (in centimeters [cm]) from the participant’s workstations and their habitual viewing distance from their smartphones.

Finally, the researchers analyzed the symptom score clusters in two steps to classify all participants into symptomatic and asymptomatic categories.

Results

In total, 30 participants were found symptomatic (symptom score >8). They had a closer viewing distance for computers and smartphones (56±8 cm vs. 62±10 cm) and (30±6 cm vs. 35±7 cm), respectively.

The authors noted a weak correlation between viewing distances of both digital devices; however, they cautioned that neither did it indicate causation nor ruled it out.

An independent t-test showed a significant difference between asymptomatic and symptomatic participants based on the viewing distance but not the font size.

Conclusions

Previous studies have found that viewing distance affects binocular vision, with reduced viewing distance (under 60cm) to visual displays causing higher eyestrain.

Even with smartphones, reducing viewing distance relieves eyestrain due to prolonged use of mobile devices. Consistent with previous studies, symptomatic participants in this study showed a correlation to viewing distance but not the font size they viewed. 

Based on these findings, the authors recommended that ophthalmologists ask patients complaining of asthenopic symptoms to increase the viewing distance for smartphones and computers beyond 62 cm, particularly if less than 35 cm, besides examining them for dry eye symptoms and recommending the 20-20-20 rule. Viewing distance is easy to measure and can alleviate digital eye strain quickly.