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Ali Shariati, Kaitlyn Liao, Caroline Yu, Juthamat Witthayaweerasak, Robert T. Chang, Ming-Hui Sun, Yaping Joyce Liao; Eye Fatigue During TV Watching: An Infrared Oculography Study of Linearly vs. Circularly Polarized LCD TV. Invest. Ophthalmol. Vis. Sci. 2016;57(12):4591.
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© ARVO (1962-2015); The Authors (2016-present)
With popularity of liquid crystal display (LCD) TVs and increased time spent on electronic devices, eye strain and fatigue are common. Some studies have used blink rate to measure fatigue, with increased blink rate correlating with greater fatigue, increased time on tasks, or dry eyes. In this study, we ask whether there is a difference in eye fatigue as measured by blink rate and ocular motor behavior while watching videos on LCD TVs with linearly or circularly polarized light.
We performed a randomized, prospective study of 28 subjects (17 males, 11 females) and 56 recordings with 500-Hz infrared oculography (RED500, SensoMotoric Instruments). The subjects were between ages 12-80 years with normal visual acuity and masked to the purpose of the study and identity of the TV. We ran idential stimulus paradigms containing fixation, saccade, and reading tasks followed by 2 videos. Subjects were randomized to watch 2 identical-appearing TVs (TCL), with linear and circular light polarization. Statistical analysis was performed using Mann-Whitney or Wilcoxon signed-rank tests (Prism).
During a reading task, the blink rate was 12.1 ± 2.2 blinks/min, which increased to 21 ± 2 blinks/min during a 1-min nature video. During the video, the subjects also exhibited exploratory volitional saccade behavior, making 164 ± 6 fixations/min and had saccade amplitudes of 4.3 ± 0.3° and mean saccade velocity of 82.1 ± 6.2°/s (N = 56). This behavior was unchanged in the first 2 min of a 10-min action video (N = 55). However, within 5-min of the action video, the number of blinks increased by 30% (P < 0.001), and the number of fixations decreased by 10% (P = 0.04), consistent with eye fatigue. While this trend was seen with linearly (L-TV) and circularly polarized TV (C-TV), the overall blink rate during the 10-min action video seen with the L-TV was 1.3 times that of C-TV (L-TV: 25.4 ± 4.0 blinks/min, C-TV: 19.4 ± 2.3 blinks/min, P = 0.2), consistent with relatively less eye fatigue with C-TV.
Eye fatigue developed rapidly, within 5 minutes of watching TV, and correlated with a significant increase in the number of blinks and a decrease in the number of fixations. Circular LCD TV may be superior to linear LCD TV with respect to eye fatigue because light waves from circularly polarized TV more closely simulate natural lighting by presenting light waves of all directions.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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