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Masakazu Hirota, Hiroshi Uozato, Shinji Arai, Yuko Shibata; Effect of Unclean Display on Accommodative Response. Invest. Ophthalmol. Vis. Sci. 2013;54(15):4257.
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© ARVO (1962-2015); The Authors (2016-present)
To assess change of accommodative response when we watched an unclean display.
Twenty volunteers (5 men and 15 women; mean ± standard deviation age, 22.2 ± 3.4 years; range, 19 to 33 years) participated in our study. All subjects had a visual acuity of 20/20 or better. In addition, we confirmed that all subjects had enough accommodation more than 7.00 D (mean ± standard deviation, 12.31 ± 0.54 D) and their near reflex was normal. Each subject’s accommodative response was measured by a target moving system WMT-1 (Grand Seiko Co., Ltd, Hiroshima, Japan). WMT-1 can move a target optionally from 0.2 to 1.0 m and it include a binocular Autorefractor WAM-5500 (Grand Seiko Co., Ltd, Hiroshima, Japan) that can measure refraction every 0.2 second in open field. We adopted iPad (Apple Inc., Cupertino, CA) on WMT-1 as a target. As an unclean display model, we covered closely to 3 pieces of tracing paper upon the iPad’s display. We compared accommodative response of a clean display and an unclean display in target distance of 1 m, 0.5 m, and 0.2 m.
The accommodative response of unclean display increased larger than that of clean display (1.0 m: clean was -0.80 ± 0.24 D, unclean was -1.03 ± 0.25 D.). When the target came near, the difference of accommodative response between control and unclean display increased (0.5 m: clean was -1.56 ± 0.25 D, unclean was -1.82 ± 0.24 D, 0.2 m: clean was -4.22 ± 0.38 D, unclean was -4.73 ± 0.74 D.). Statistical significant differences were found between the accommodative response of unclean display and of clean display in all target distances (Wilcoxon signed rank test, p < 0.001)
The accommodative response of unclean display was larger than that of clean display. The increase in necessary accommodative response may lead to asthenopia. We should keep a display clean to prevent eye fatigue.
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