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2023-05
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SJohnson all signed + Thesis_Sophia Johnson.pdf
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Purpose: The use of digital devices has increased substantially over the past two decades across all age groups, particularly during the recent pandemic, for both vocational and avocational purposes. Digital eye strain (DES) involves a range of visual and ocular symptoms that can be categorized into oculomotor/refractive abnormalities or dry eye symptoms. The so-called 20-20-20 rule, whereby individuals are advised to fixate an object at least 20 feet (6m) away for at least 20 seconds every 20 minutes is widely cited as a method for minimizing symptoms. Unfortunately, there is little or no peer-reviewed evidence to support this so-called rule. Accordingly, the aim of the present investigation was to determine whether 20-second breaks are indeed effective in reducing the adverse effects of digital device usage, and if so, then to identify the specific schedule that has the greatest success in controlling symptoms.
Methods: The study was performed on 30 young, visually-normal subjects who performed a highly demanding 40-minute reading task from a tablet computer. The task required them to read random words and to identify which began with a specific letter chosen at random by the experimenter. The task was undertaken on four separate occasions, with 20-second breaks being allowed every 5, 10, 20 or 40 minutes (i.e., no break), respectively. Both before and immediately 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 the trial.
Results: A significant increase in post-task symptoms (with respective to the pre-task value) was observed for all four trials (p<0.001). However, there was no significant effect of scheduled breaks on reported symptoms (p=0.70), reading speed (p=0.93) or task accuracy (p=0.55).
Conclusions: While widely cited as a treatment option, these results do not support the proposal of using the 20-20-20 rule as a therapeutic intervention for DES. Future studies should look at alternative break schedules to determine their efficacy.