스마트폰 사용이 시기능에 미치는 영향

Impacts of Smartphone Use on Visual Function

Purpose: To analyze the change of visual function according to use time of smartphone in healthy adults. Methods: The medical records of 40 healthy adults who visited our hospital for eye fatigue, visual disturbance, and eye irritation and had used a smartphone more than 4 hours a day, and who agreed to and cooperated with the smartphone usage time reduction after initial visit were analyzed. Subjective visual fatigue assessed by asthenopia questionnaire was reviewed. Best corrected visual acuity, spherical equivalent, amplitude of accommodation, alignment, stereoacuity, tear film break up time, and contrast sensitivity were reviewed. The use time of smartphone at follow up visit was investigated, and the changes in visual function after the reduction were analyzed. Results: Asthenopia questionnaire score was significantly higher when smartphone usage time was ≥ 4 hours (7.8 ± 5.4) than when it was < 1 hour (3.6 ± 4.4) (p < 0.001). Amplitude of accommodation was significantly lower when smartphone usage time was ≥ 4 hours (10.9 ± 1.2 diopters [D]) than when it was < 1 hour (11.7 ± 1.5 D) (p < 0.001). Tear film break up time was significantly shorter when smartphone usage time was ≥ 4 hours (7.5 ± 1.9 seconds) than when it was < 1 hour (8.4 ± 1.8 seconds) (p < 0.001). There was no significant difference in best corrected visual acuity, spherical equivalent, alignment, stereoacuity, and contrast sensitivity according to smartphone usage time. Conclusions: Long term use of smartphone can significantly increase subjective visual fatigue and reduce amplitude of accommodation and tear film break up time. In modern society where the use of visual display is increasing, close observation and caution regarding use of the video display units, especially smartphones, are needed.