The average American spends an estimated seven hours a day staring at digital device screens. The majority report experiencing reduced visual acuity, headaches, dry eye, eye strain and neck pain, which we commonly call Digital Vision Syndrome (DVS). In a recent study reported in News Medical Life Sciences, researchers hypothesized that closer viewing distance and smaller font size increase the demand on binocular vision, which in turn, aggravates or worsens DVS symptoms. They believe that viewing digital devices from a short distance (less than 35 cm or 14 inches) compromises accommodation and the ability to fixate on objects and perceive them as single (vergence). (Ramteke, S. and Satgunam, P. 2023) At what distance should digital devices be viewed? (Nature. doi: 10.1038/s41433-023-02781-9. https://www.nature.com/articles/s41433-023-02781-9.)
To evaluate the effects in real-world work settings, they measured viewing distance in centimeters from 114 participants’ workstations and their habitual viewing distance from their smartphones. Participants were aged 19 to 50 years old. Thirty participants were found to have DVS symptoms. They had a closer viewing distance for computers (56 cm or 22 inches) and smartphones (30 cm or 12 inches) as compared to the asymptomatic group, which measured 62 cm (24 inches) for computers and 35 cm (14 inches) for smartphones. However, the study found no significant difference between asymptomatic and symptomatic participants based on font size, which is consistent with previous studies.
The American Optometric Association recommends viewing a computer screen at a distance of 20 to 28 inches (51 to 71 cm) and digital devices from 13 to 20 inches (33 to 51 cm). However, viewing distances vary with screen size. For example, smart watches are usually viewed from about 16 inches (40 cm), smartphones from about 12 inches (30 cm) and tablets from about 12 to 20 inches (30 to 50 cm). Eyecare professionals may recommend increasing those distances for patients with DVS.
The researchers and eyecare professionals also recommend the 20-20-20 rule. Regular eye examinations and eyewear with lenses prescribed and designed for digital device use, including anti-reflective coatings and blue filters, are also paramount in alleviating DVS symptoms. Even if glasses are not needed for driving, reading or other activities, they may offer benefits for a minor vision problem that is aggravated by computer use. A mild eyewear prescription may be needed to reduce vision stress on the job. Patients should be aware of and inform the eyecare practitioner about job tasks and on-the-job sight distances. Of the multiple factors contributing to DVS, proper viewing distance is easy to measure and correct.
• Linda Conlin
Pro to Pro Managing Editor
[email protected]
