Comparison of Accommodative Responses to e-Ink vs. LCD vs. Standard Ink on Hard Copy.

Background: Adverse visual symptoms with electronic devices have been reported, but causes have yet to be clearly defined. Previous studies have neither 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 an LCD device in young, healthy adults with normal accommodation. Methods: Subjects were 42 healthy adults, aged 22 to 33 years, with near acuity 20/20 (6/6) or better in the tested eye. Normal accommodation was verified with accommodative amplitude and facility (+/-2.00 flippers) tests. The reading text was presented at 40 cm, and text size and device luminance were matched across devices. While the subject read the passage aloud, pupil size was measured. Accommodative responses were obtained 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 test were used to compare mean pupil size and mean accommodative response across devices. The differences in mean pupil size for paper versus e-ink (5.1 ± 0.9 vs. 5.5 ± 0.8, p<0.01) and LCD versus e-ink (5.1 ± 0.9 vs 5.5 ± 0.8, p<0.01) were significant. By retinoscopy, the difference in mean accommodative response was significant only for e-ink and LCD (1.48 ± 0.76 D vs. 1.78 ± 1.26 D, p<0.01). By autorefraction, no significant differences in mean accommodative response were 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 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. [ABSTRACT FROM AUTHOR]