Abstract
Purpose :
Accommodative dysfunction and visual fatigue with electronic devices have been reported, but causes have yet to be clearly defined. Previous studies have not equated stimulus luminance across devices nor studied subjects with verified normal accommodation prior to testing. Pupil size during device use also has not been explored.
We compared pupil sizes and accommodative responses to targets of similar size displayed with ink on paper, an E-ink reader, and LCD device in young adults with normal accommodation.
Methods :
Subjects were 42 adults, aged 22 to 33 years, with near acuity 20/20 or better in the tested eye. Exclusions included strabismus, amblyopia, disease affecting the crystalline lens anatomy or function, and medications potentially affecting accommodation. Normal accommodation was affirmed with accommodative amplitude and facility (+/-2.00 flippers) tests. The reading text was presented at 40 cm, with near retinoscopy done before autorefraction. Text size and device luminance were matched across devices. Monocular measures of accommodative response were obtained through distance correction while the subject read the passage aloud. Pupil size was measured while the subject read from each device, and accommodative responses were measured twice with near retinoscopy and twice with an open field autorefractor for each device.
Results :
One-way ANOVA for correlated samples and Tukey’s HSD for posthoc analysis were used to compare mean pupil size and mean accommodative response across devices. The differences in mean pupil size for paper vs E-ink (5.1+/-0.9 vs 5.5+/-0.8, p<.01) and LCD vs E-ink (5.1+/-0.9 vs 5.5+/-0.8, p<.01) were significant. By retinoscopy, the difference in mean accommodative response was significant only for E-ink and LCD (1.48+/-0.76D vs 1.78+/-1.26D, p<.01). By autorefraction, no significant difference in mean accommodative response was found across device type. Linear regression showed that accommodative response was not predicted by pupil size for any of the devices.
Conclusions :
In this group of young adults with normal accommodation, accommodative response while reading at 40 cm was not significantly different for ink on paper, E-ink, or LCD devices of matched luminance. Pupil size did not predict accommodative response for any device. Whether accommodative response of subjects with accommodative dysfunction would differ significantly across these devices remains to be explored.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.