Abstract
Purpose :
Since smartphone functions including internet accessibility have been making remarkable progress, the penetration rate in 2016 was also rapidly increased to 71.8% in Japan. According to the survey of human behaviors in a train in 2013, with the responses from 35.3% of the passengers as “I was operating a mobile phone”, it was demonstrated that the mobile phone has been used in various scenes of people’s daily life. However, while long-time use of Information and Communication Technology (ICT) equipment such as smartphone may increasingly cause a damage to eyes, there is also concern for “Asthenopia” as well as Visual Display Terminal (VDT) syndrome. In the present study, we made the assumption that people use or operate smartphone in a train, and then we examine a damage influence on eyes with a change in pupil diameter as an evaluation index for autonomic nerve system.
Methods :
The study targeted 17 college students (mean±standard deviation: 21.8±0.7 years old) without any ophthalmic disorder except ametropia. Since it is assumed that a railway car would be shaking at the time of a ride on a train, random oscillation (0.9±1.3 mm) was given to a smartphone within the range of 4.5 mm by use of a vibration device. As the experiment of visual load, we conducted a visual search task as a test subject looks for the letter “T” from many letters of “L”. The smartphone used in the experiment was AQUOS R SHV39 (screen resolution: 2,560x1,440, screen size: 5.3 inches, viewing distance: 33 cm). We conducted a quantitative evaluation of subjective fatigue by Simulation Sickness Questionnaire (SSQ) before/after the experiment for visual load, and also made a measurement of pupil diameter by ACOMOREF2 K-model. In the measurement of ACOMOREF2 K-model, we could measure pupil diameter with 3D-adjusted load the same as viewing distance.
Results :
The study found a significant correlation between SSQ change before/after the visual load and a change in pupil diameter (r=-0.5, P=0.048). The test subject with a severe subjective fatigue indicated a miotic tendency, and it could be detected objectively.
Conclusions :
If it is assumed that a smartphone is used under the shaking condition of train, the study recognized that it might possibly cause asthenopia subjectively or objectively. Thus, for usage of smartphone, we consider it would require an effective preventive measure for VDT syndrome.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.