Visual discomfort among university students who use CAD workstations

BACKGROUND: Extensive literature in ergonomics and optometry has indicated that computer use is closely associated with visual problems. Computer-Aided Design (CAD) requires a substantial effort on behalf of the visual system. The manifestations of visual fatigue phenomena may affect the working behavior and the human-system interaction. OBJECTIVE: The aim of this survey is to identify the normal working conditions and how the eventual visual fatigue phenomena are able to influence the working behavior of CAD users. METHODS: A questionnaire was created and submitted to a sample of 150 university students, who attend the Faculty of Engineering of the University of Pisa (Italy). RESULTS: The questionnaire results show that university students spend on average 7 hours per day at the computer for CAD drafting. Most of the participants work in strongly lit environments, with high brightness screens and negative polarity. Such conditions cause high contrasts in luminance, especially between screen and surfaces that fall within the field of vision. The results show that 135 out of 150 students report visual fatigue during long CAD sessions, which in most cases leads to difficulty in continuing the activity and changing usual working behavior. CONCLUSIONS: The results of the questionnaire show that the university students work in highly variable lighting conditions and with little attention on the luminance distribution on the field of view. This has highlighted the importance, for VDT workstations, of not limiting the risk analysis to the postural ergonomics (how usually occurs) but extend it to the workplace as a whole, analyzing also the ergonomics of vision, which involves different consideration on the natural and artificial lighting of the workplace and on the characteristics of the display.