Abstract
The main objective of this study was to investigate a method of reducing the amount of visual fatigue which is often associated with VDT usage. Specifically studied was the effect of the provision of refractive power on various indicants of visual fatigue (distant focus time, eye-blink rates, and visual acuity), visual-search performance on a computer, and evaluative responses on a questionnaire. Refractive power was provided with the use of nonprescription reading glass. Two different character sizes (4.8 and 5.8 mm) and two different viewing distances (508 and 666 mm) were also studied to determine if an increase in the visual angle of characters would result in significant improvements.
After analyzing the data with a repeated measures analysis of variance, it was determined that the use of the reading glasses resulted in significantly (p < 0.05) lower: distant focus times and left-eye acuity measurements. There were no significant benefits on other measurements taken. The glasses resulted in fewer visual complaints on several questionnaire responses, but there was not a strong preference for the glasses. There were virtually no differences between the two different character sizes and viewing distances studied.
It is concluded that if the reading glasses are used under certain conditions (the user is nonastigmatic and has at least 20/20 vision - either corrected or uncorrected) then they may help reduce some of the visual fatigue associated with VDT usage for operators in the field.
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