The effect of Vaccinium uliginosum extract on tablet computer-induced asthenopia: randomized placebo-controlled study

Background: To investigate the alleviation effect of Vaccinium uliginosum extract (DA9301) on tablet computer-induced asthenopia. Methods: This was a randomized, placebo-controlled, double-blind and parallel study (Trial registration number: 2013-95). A total 60 volunteers were randomized into DA9301 (n = 30) and control (n = 30) groups. The DA9301 group received DA9301 oral pill (1000 mg/day) for 4 weeks and the control group received placebo. Asthenopia was evaluated by administering a questionnaire containing 10 questions (responses were scored on a scales of 0-6; total score: 60) regarding ocular symptoms before (baseline) and 4 weeks after receiving pills (DA9301 or placebo). The participants completed the questionnaire before and after tablet computer (iPad Air, Apple Inc.) watching at each visit. The change in total asthenopia score (TAS) was calculated and compared between the groups Results: TAS increased significantly after tablet computer watching at baseline in DA9301 group. (from 20.35 to 23.88; p = 0.031) However, after receiving DA9301 for 4 weeks, TAS remained stable after tablet computer watching. In the control group, TAS changes induced by tablet computer watching were not significant both at baseline and at 4 weeks after receiving placebo. Further analysis revealed the scores for tired eyes (p = 0.001), sore/aching eyes (p = 0.038), irritated eyes (p = 0.010), watery eyes (p = 0.005), dry eyes (p = 0.003), eye strain (p = 0.006), blurred vision (p = 0.034), and visual discomfort (p = 0.018) significantly improved in the DA9301 group. Conclusions: We found that oral intake of DA9301 (1000 mg/day for 4 weeks) was effective in alleviating asthenopia symptoms induced by tablet computer watching.