VDT Operator Pupil Diameter Changes,Accommodation Changes and Subjective Comfort/Discomfort Score Changes over a Working Day

Abstract

Pupil diameter, accommodation and subjective comfort/discomfort were measured at certain times during the working day. Six subjects, all experienced typists, were used and worked two full days in a VDT workstation using two different data presentations, i.e. hard copy-screen and split screen, and a data entry and a file maintenance/editing task. An Applied Science Laboratory 1998 computer controlled eye monitor system was used to collect and analyze the pupil diameter data and the eye scanning data. A field laser optometer was used to measure the accommodative state of the subjects' lenses for a viewing distance of 6m (.17 diopters) before and immediately after each work session.

The results of this study indicate that neither the pupil diameter changes nor the accommodation changes reveal any consistent pattern which would enable one to predict reliably the actual mental workload, general fatigue, ocular discomfort or fatigue of VDT operators. On the whole the changes in accommodation over three hours of VDT work (near-visual task) follow the trend to a slightly more myopic vision for a distant 6m target. But these changes are relatively small and are accompanied by a rather large variability. The scores for the nine visual comfort/discomfort questions were rather low when compared to some of the musculoskeletal comfort/discomfort questions. Also, the rest breaks and the lunch break did produce rather small and not as consistent decreases in the ocular comfort/discomfort scores when compared with the effects on some of the musculoskeletal comfort/discomfort scores. Correlations between accommodation and some of the visual comfort/discomfort scores were examined to see how reliable the changes in accommodation measured with the field laser optometer were in predicting visual problems such as “hard to see sharply”. None of the correlations were statistically significant.

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References

National Research Council Video Display, Work and Vision. National Academy Press, Washington, D.C., 1983.

Ostberg

Hedman

A Field Laser Optometer for Ergonomics of Vision Investigations. University of Lulea, Technical Report 1979:52 T, 1979.

Ostberg

Powell

Blomkvist

A-Ch.

, Laser Optometry in Assessment of Visual Fatigue. University of Lulea, Technical Report 1980:1 T, 1980.

Rupp

B.A.

McVey

B.W.

Taylor

S.E.

, “Image quality and the accommodation response”, Published in Grandjean

, ed: Ergonomics and Health in Modern Offices, Taylor & Francis, London and Philadelphia, 254–259, 1984.

Zwahlen

H.T.

, “Pupillary Responses When Viewing Designated Locations in a VDT Workstation”, Published in Grandjean

, ed: Ergonomics and Health in Modern Offices, Taylor & Francis, London and Philadelphia, 339–345, 1984.

Zwahlen

H.T.

, “Measurement of Visual and Performance Adaptation Behavior on Video Display Terminals”, paper presented at the International Conference on Occupational Ergonomics, Toronto, Canada. Published in Proceedings, pp. 242–246, May 1984.

Zwahlen

H.T.

Hartmann

A.L.

Rangatajulu

S.L.

, “Video Display Terminal Work with a Hard Copy-Screen and a Split Screen Data Presentation.” Ohio University, Dept. of Industrial and Systems Engineering Research Report, prepared for NIOSH, distributed by The Report Store, Lawrence, Kansas 66044, 375 pp., July 1984.