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Abstract
This paper reports the results of a two-year survey of the visual problems associated with the use of visual display units (VDUs). The survey examined both discomfort levels and visual function, and asked whether there were differences in these measures between subjects who used a VDU in the completion of their tasks and controls who did not. In total, 202 subjects were examined. The main study examined four groups of which two, Data Preparation and Word Processing (WP) used a VDU in the completion of their tasks, while the other two, General Clerical and Typing (TY), did not. Subjective measures of visual discomfort and objective measures of visual function were taken at both the beginning and end of the day.
Two analyses were performed on the data; the first considered all four groups together, and the second directly compared the WP and TY groups—these two groups being considered well matched. The first analysis showed that statistically significant differences existed between the groups at the end of the day. However, differences were also shown between the groups at the beginning of the day, and when the measure ‘change over the day’ was used, no significant differences attributable to the VDU were found. The second analysis found no significant differences between the TY and WP groups, nor were any trends apparent.
A further study was done on ten subjects who alternated on a daily basis between using a word processor and a typewriter. No significant differences were found between the days using one and those using the other, confirming the above finding.
Whilst both optometric measures of visual function and reported visual discomfort did change over the day, we conclude we have no evidence lo support the idea that the VDU is in itself a causal factor of these changes to any greater extent than is the paper in a typewriter.