RESUMO
PURPOSE: The blue light emitted from electronic devices may be harmful to the eye. We investigated whether internet-protocol television (TV) with lowered blue light emission reduced ocular fatigue. METHODS: A total of 98 healthy subjects were recruited. They watched an animated movie (A) and an identical version except for reduced blue light (B), sequentially for 1 hour in random order. Before and after watching the movies, we measured the distance and near refraction and tear break-up time objectively. Ocular discomfort score and the earliest onset time of the ocular fatigue symptoms were also measured using our specially designed subjective ocular discomfort scale. RESULTS: The median age of the participants was 28.5 years, and there were 56 females out of 98 total participants. Both distance and near refraction were not significantly different before versus after watching the movies, nor between viewing movies A and B. However, the accommodative amplitude measured by subtracting the near refraction from the distance refraction was found to be greater after watching movie B compared with movie A in a subset of subjects with hyperopia [1.92 vs. 1.72 diopters (D) for the right eye and 2.14 vs. 1.83 D for the left eye; p = 0.04 and p < 0.01, respectively]. The ocular discomfort score was lower (15.40 vs. 12.85; p = 0.10), but not significantly, and the earliest ocular fatigue onset time was significantly delayed (23.48 vs. 34.51 minutes; p < 0.01), after watching movie B. CONCLUSIONS: Reduction of blue light emission alleviated ocular fatigue caused by TV displays. Watching TV with lower blue light may provide benefits to hyperopic individuals by reducing eye strain and improving the accommodative amplitude.