Reduction of Blue Light Emission in Internet-protocol Television and Its Effect on Ocular Fatigue

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.

Severe symptoms of short tear break-up time dry eye are associated with accommodative microfluctuations.

AIM: Validating the hypothesis that accommodative microfluctuations (AMFs) may be associated with severe symptoms in short tear break-up time (BUT) dry eye (DE). METHODS: This study included 12 subjects with short BUT DE (age: 49.6±18.3 years). Diagnoses were performed based on the presence of DE symptoms, BUT ≤5 s, Schirmer score >5 mm, and negative keratoconjunctival epithelial damage. Tear evaluation, AMF, and functional visual acuity (VA) examinations were conducted before and after DE treatment. The AMF parameters evaluated were: total high-frequency component (HFC), HFC with low accommodation for the task of staring into the distance (HFC1), HFC with high accommodation for deskwork (HFC2). A subjective questionnaire of DE symptoms was also performed. RESULTS: Mean BUT increased from 1.9±2.0 to 6.4±2.5 s after treatment (P<0.05). The mean logarithm of the minimum angle of resolution functional VA significantly improved (from 0.19±0.19 to 0.12±0.17; P<0.05). Mean power spectrum values for total HFC and HFC1 decreased (from 61.3±5.7 to 53.8±6.6 dB and from 62.9±10.5 to 52.4±6.2 dB, respectively; P<0.05), while the mean HFC2 power spectrum values did not differ before and after treatment (P>0.05). Subjective DE symptoms were reduced in nine patients. CONCLUSION: Along with the improvement of BUT after treatment, DE symptoms diminished and HFC1 and functional VA improved, suggesting that tear film instability is associated with deterioration of functional VA, AMF, and DE symptoms.

The Ocular Fatigue of Watching Three-Dimensional (3D) Images

PURPOSE: To compare ocular fatigue, non-ocular symptoms, and ocular surface changes, such as tear break-up time (BUT) and ocular surface temperature, after watching 2-dimensional (2D) and 3-dimensional (3D) images. METHODS: Fourteen volunteers were enrolled in the present study. Subjects watched 2D as well as 3D images and answered questions regarding ocular fatigue and general symptoms such as headache. Before and after watching images, the spherical equivalent, degree of conjunctival injection, tear BUT, and ocular surface temperature were measured and the amount of change was analyzed. While watching images, subjects answered questions regarding ocular fatigue and the time when they began to feel definitive symptoms. RESULTS: Watching 3D images induced a greater degree of ocular fatigue, headache, and decreasing concentration than watching 2D images (p = 0.038, 0.003, and 0.045, respectively). While watching images, 3D images induced a greater degree of ocular fatigue than 2D images and caused subjects to feel earlier ocular fatigue (3D: 54.86 min, 2D: 78.57 min, p = 0.002). Spherical equivalents became more myopic after watching 3D images. CONCLUSIONS: After watching 3D images, a greater degree of ocular fatigue, headache, and decreasing concentration was induced and a shorter time to feel definitive ocular fatigue was observed than after watching 2D images. In addition, spherical equivalents changed myopically after watching 3D images.

The Objective Methods to Evaluate Ocular Fatigue Associated With Computer Work

PURPOSE: To develop methods for the objective measurement of ocular fatigue. METHODS: Fifteen patients were enrolled in the present study. Subjects performed visual tasks on a computer for one hour. A survey of ocular fatigue was conducted with a questionnaire. Tear break-up time, blinking rate, ocular protection index, conjunctival injection, maximal blinking interval, temperature of the ocular surface, and visual evoked potential were evaluated before and immediately after the task. Surface electromyography of the orbicularis oculi muscle was performed before and during the task. RESULTS: The survey showed increases in subjective ocular fatigue in all subjects. Tear break-up time, ocular protection index and maximal blinking interval decreased, while temperature of the ocular surface increased after the task. Conjunctival injection showed a tendency to increase. Electromyography, and visual evoked potential did not change significantly. CONCLUSIONS: In the present study, tear break-up time, ocular protection index, maximal blinking interval, and temperature of the ocular surface changed as ocular fatigue increased. Therefore, these measures can be objectively used for the evaluation of ocular fatigue.