Effects of using a screen filter on call center workers' visual fatigue measurement.

This study evaluated the potential effectiveness of screen filters in relieving visual fatigue. Critical flicker frequency (CFF), accommodation power, visual acuity, and subjective rating of visual fatigue were evaluated at four different stages: without screen filter, screen filter use of 2.5 mo., 5 mo., and 12 mo. For each stage, all measurements were taken before and after an 8-hr. workday. Analysis of variance was performed to test whether the screen filter use or measurement time had a significant effect on any of the visual fatigue measurements. The results indicated visual acuity was significantly improved after the use of a screen filter, while after the screen filter was installed, the CFF reading showed visual fatigue was more pronounced. Significant improvement in subjective ratings of double vision on screen was found after the screen filter use of 2.5 mo., but improvements disappeared after continuous use at 5 mo. A Hawthorne effect could have contributed to the short-term relief in visual fatigue and inconsistent findings in other visual performance measurements. Sorting out frequently used questions into a few definable areas and data sets might reduce the screen viewing time and visual fatigue more effectively.