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Damien Paille, Jean-Luc Perrin, Amandine Debieuvre; New postural behaviors related to the use of digital devices involve new characteristics for occupational lenses. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):4304.
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© ARVO (1962-2015); The Authors (2016-present)
Since the last decade, we see an explosion in the use of smartphones, tablets, e-book readers and hybrid devices which combine laptop and mobile functions. Those tools, also called “handheld or mobile devices”, can be use everywhere: standing up whilst commuting, sat in a couch, lying in bed... This study aims to investigate the impact of the use of new technology devices on postural behavior in everyday life.
22 subjects wearing their usual correction were recruited in the experiment. They wore a helmet with 4 reflective markers and were equipped with 4 additional markers (Left and right shoulder, torso and clavicle). Once fitted, they performed a scenario mixing 7 different tasks (weather forecast, writing an email, reading an email, video game, video, searching information, reading a text) on three digital devices (smartphone, tablet and ebook reader) in three different conditions (standing, sitting and lying). Postural data were recorded thanks to a VICON motion tracking system. Subjects were asked to act as they would do in real life during the experiment. For each task, several parameters such as distance between the eyes and the middle of the device, head declination, eye declination, head roll, head in trunk rotation and shift were then computed.
During all the tasks, the head stays perpendicular to the trunk (Mean Head in trunk rotation: 0.13±1.4°) with no roll (Mean Head roll: 2.87±1.23°). The middle of the device remains centered on the sagittal plane of the user (Mean head shift: 2.3±2.5°). Contrast analysis showed that eye declination was higher when standing compared to sitting and lying tasks (difference 6.68°, CI(95%) [4.87; 8.50], p<0.01). The distance of use was smaller with smartphones compared to tablets or ebook readers (difference 5.35cm, CI(95%) [3.92; 6.78], p<0.01). Results showed small reading distances with digital devices (smartphones: 33.79cm, tablets: 39.70cm, ebook readers: 38.05cm).
The experiment showed that digital device users are adopting rigid postures in front of their devices. Moreover, the distance of use is smaller and eye declination higher with electronic devices compared with traditional paper media. Occupational lenses must thus take into account these new postural behaviors in order to answer all the wearer needs.
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