A recent study provided evidence that a 20-second break from near work every 20 minutes isn’t enough to positively impact ocular growth. Photo: Getty Images.
Given that success in today’s society requires children to perform sustained near work most days of the week, the only workable option to help curb near work-related myopia development/progression is to suggest periodic breaks. Practitioners commonly recommend the 20/20/20 rule with hopes that, if patients follow it, they will reduce their risk of myopic progression. However, the results of a recent study provide little or no support for the use of 20-second breaks to alleviate symptoms of digital eye strain.
The research determined that, if the goal of the work breaks is to reduce both the accommodation and vergence responses following sustained fixation on a near object, then 20 seconds of distance viewing may not be sufficient enough to allow these sustained responses to dissipate fully.1 A commentary on the same topic (but not this specific recent study) that looked at current animal model data also suggests repeated episodes of 20 seconds were ineffective at reducing myopia development, and instead indicated that sustained breaks of five or more minutes every hour are needed to negate myopiagenic effects.2 Both were published ahead of print in Optometry and Vision Science.
The study evaluated the effect of different break schedules during the course of a highly demanding word search task. Following the 20-20-20 rule, individuals were advised to fixate on an object at least 20 feet away for at least 20 seconds every 20 minutes. This research was carried out on 30 young subjects who performed a 40-minute cognitively demanding reading task from a tablet computer. The task was undertaken on four separate occasions, with 20-second breaks allowed every five, 10, 20 or 40 (i.e., no break) 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 were quantified during each trial.1
A significant increase in post-task symptoms (with respect to the pre-task value) was observed for all four trials. However, there was no significant effect of scheduled breaks on reported symptoms, reading speed or task accuracy.
“These findings should not be interpreted as evidence that taking breaks is not helpful,” the authors of the first study wrote in their paper. “Rather, it seems likely that longer break durations or a different frequency of breaks may be required to produce significant effects.”
“Providing more specific instructions on appropriate fixation targets during the break intervals would likely be helpful, rather than a simple statement of look into the distance,” the researchers suggested. While participants were asked to look out of the window at a distant target about 20 feet away during the break interval, one cannot be certain that they actually were focused on the far stimulus. Because the participants were not asked to view or comment on a specific detail of the distant target, the researchers believe this may have represented a poor stimulus to accommodation and vergence, especially during the later stages of the trial when subjects knew they would be returning to the reading task.
The team noted that even simply having the subject close their eyes during the break interval, rather than having them fixate on a distant target, might be beneficial. “This would allow a layer of tears to be spread over the anterior surface of the cornea, which could make the subject more comfortable,” they noted.1
Longer Break Times Needed
The commentary was a clinical perspective on recent myopia research. These researchers’ review of myopia animal model paradigms led them to propose that the ideal break would not just consist of not doing near work but also include going outside and looking at distant objects for a minimum sustained break of five or more minutes. The data suggested that instead of taking a 20 second break every 20 minutes, it might be more effective to take a five minute break every hour. However, this second team of researchers believes the breaks likely do not need to be as closely spaced as every 20 minutes.2
“Clearly more research needs to be done, both in further determining the temporal parameters of anti-myopia stimuli, especially in species more closely related to humans, and also in targeted epidemiological work that looks more carefully at how the pattern of children taking breaks from near work correlates to the development and progression of myopia,” the authors of the commentary wrote.
1. Johnson S, Rosenfield M. 20-20-20 rule: are these numbers justified? Optom Vis Sci. December 6, 2022. [Epub ahead of print].
2. Pucker AD, Gawne, TJ. Fighting myopia with intermittent nearwork breaks: 20 seconds every 20 minutes might not be enough time. Optom Vis Sci. December 5, 2022. [Epub ahead of print].