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Kathleen Hoang, Mark Rosenfield, Joan K Portello; AUTONOMIC INNERVATION AND DIGITAL EYE STRAIN. Invest. Ophthalmol. Vis. Sci. 2017;58(8):5419.
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© ARVO (1962-2015); The Authors (2016-present)
In today’s world, the viewing of electronic displays has become ubiquitous. Up to 90% of individuals experience significant ocular and visual symptoms when viewing digital screens. Previous work has shown changes in blink patterns and the position of the upper eyelid when reading from electronic displays. This study seeks to determine whether these changes are produced by variations in autonomic innervation to the eye during the course of a sustained near task.
The study was performed on 25 young, visually-normal subjects, who participated in 2 experimental sessions. In the first, subjects were required to read from an electronic reader for a continuous 20 minute period at a distance of 40cm. In the second trial, subjects fixated a 0.1 cpd Difference of Gaussian (DOG) grating at a distance of 40cm. While fixating this stimulus, subjects were given two mental tasks, namely either counting backwards in intervals of 1 or 7, for a 10 minute period. To assess autonomic innervation the following parameters were quantified during the trials: heart rate (HR), blood pressure, pupil size, vertical palpebral aperture dimension, blink rate and prevalence of incomplete blinks. At the end of each session, subjects completed a questionnaire concerning symptoms of eyestrain, ocular discomfort and dry eye experienced during the task.
While reading from the electronic device produced a high symptom score, the only parameters which showed significant post-task changes following the reading task were HR (mean decrease = 8.56 bpm; p < 0.001) and incomplete blinking (the percentage of blinks deemed incomplete increased by 30.6%; p < 0.001). Both counting tasks also produced a significant decrease in HR (mean decrease = 9.12 bpm and 5.00 bpm; p < 0.001 and p < 0.005, for counting in 1’s and 7’s, respectively), and a decrease in the percentage of blinks recorded as incomplete (mean decrease = 13.3% and 12.0%; both p < 0.05, for counting in 1’s and 7’s, respectively).
While marked symptoms of digital eye strain were observed immediately after reading from a digital screen, these symptoms were not associated with changes in autonomic innervation to the eye. Accordingly, it appears that digital eye strain and the concurrent changes in blink amplitude do not result from the cognitive demand of the near-vision task.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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