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Objective Evaluation of Relationship Between Tear Film Stability and Visual Fatigue
Maki Watanabe1, Masakazu Hirota2,3,4,5, Ryusei Takigawa2
1Division of Orthoptics, Graduate School of Medical Care and Technology, Teikyo University, Itabashi-ku, Tokyo, Japan.
Clinical Optometry
|July 7, 2025
Summary
Visual fatigue significantly reduces tear film stability, as measured by non-invasive tear film break-up time (NI-BUT) and binocular fusion maintenance (BFM). These objective findings confirm a link between reduced tear film quality and visual fatigue.
Area of Science:
- Ophthalmology
- Vision Science
- Optometry
Background:
- Visual fatigue is a common complaint among individuals undergoing prolonged visual tasks.
- Objective measures are needed to quantify the physiological impact of visual fatigue on ocular surface health.
- Tear film stability is crucial for maintaining clear and comfortable vision.
Purpose of the Study:
- To investigate the relationship between tear film stability and visual fatigue.
- To utilize objective measurements: non-invasive tear film break-up time (NI-BUT) and binocular fusion maintenance (BFM) test.
- To assess the impact of a 30-minute visual task on these parameters.
Main Methods:
- Eleven young adults (mean age 20.7 years) participated.
- Non-invasive tear film break-up time (NI-BUT) was measured using mire ring distortion.
- Binocular fusion maintenance (BFM) was assessed via liquid crystal transmittance after inducing heterophoria.
Main Results:
- NI-BUT significantly decreased after the visual task (9.12s pre vs 5.69s post, P=0.011).
- BFM significantly decreased after the visual task (0.95 pre vs 0.75 post, P=0.012).
- Changes in NI-BUT and BFM were positively correlated (R²=0.385, P=0.042).
Conclusions:
- Objective measurements demonstrate a significant reduction in tear film stability post-visual task.
- The study supports a direct association between decreased tear film stability and visual fatigue.
- These findings highlight the physiological consequences of prolonged visual exertion on ocular surface integrity.
