The often-cited 20-20-20 rule to avoid digital eye strain may not be an effective therapeutic intervention as previously thought, new research has revealed, and efforts should now focus on finding more optimal strategies to avoid the condition.
“Regular breaks are frequently recommended by clinicians to minimise digital eye strain,” Ms Sophia Johnson and Mr Mark Rosenfield, both of the SUNY College of Optometry, wrote in a study in Optometry and Vision Science.
“The so-called 20-20-20 rule, whereby individuals are advised to fixate on an object at least 20 feet (6 m) away for at least 20 seconds every 20 minutes is widely cited. Unfortunately, there is relatively little peer-reviewed evidence to support this rule.”
Their investigation aimed to determine whether scheduled breaks are effective in reducing the adverse effects of digital device usage.
The use of digital devices has increased substantially in recent years across all age groups for both vocational and avocational purposes, with a wide range of proposed therapeutic and management options, including optical, medical and ergonomic interventions.
The study involved 30 young people who performed a 40-minute, cognitively demanding reading task from a tablet computer. It required them to read random words and to identify which ones began with a specific letter chosen by the experimenter.
The task was undertaken on four separate occasions, with 20-second breaks being allowed every 5, 10, 20 or 40 minutes, respectively. Both before and after each trial, subjects completed a questionnaire regarding ocular and visual symptoms experienced during the session.
Additionally, both reading speed and task accuracy was quantified during each trial.
The researchers found a significant increase in post-task symptoms for all four trials, however, there was no significant effect of scheduled breaks on reported symptoms, reading speed or task accuracy.
“While widely cited as a treatment option, these results do not support the proposal of using 20-second scheduled breaks as a therapeutic intervention for digital eye strain,” Johnson and Rosenfield wrote.
“This is not entirely surprising, since there appears to be little or no existing evidence to support the use of the 20-20-20 rule to minimise symptoms. However, these findings should not be interpreted as evidence that taking breaks is not helpful.”
They said further studies should examine the effect of longer breaks at varying intervals to determine their effectiveness, rather than passively viewing a far target; for example standing up and moving around could also be beneficial.
“Given the very high – and apparently increasing – prevalence of discomfort associated with the almost universal use of digital screens, finding procedures to reduce the level of symptoms is essential,” they concluded.
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