Measure of visual fatigue as a link between visual environment and visual and non-visual functions of VDT users A review on what we have and what we need

Over the last few decades, increasing number of VDT use in workstations has led to various health-related problems, among which visual fatigue is the most common. Within the framework of visual ergonomics of VDT workstations, lighting conditions are initially considered factors for being involved in the visual and non-visual functions on VDT users. Visual fatigue is a common eye-related phenomena among VDT users which manifests itself in visual and non-visual functions, but the origin is not always definite; could be associated with the VDTs, with the environmental lighting, or both. Up to now, it has been measured through objective and subjective methods in order to obtain the influencing factors; however, many of them were conducted under laboratory conditions. Moreover, the evaluation criteria were not in a multidimensional manner, which also ought to cover other visual and non-visual risks related to visual fatigue. This paper presents the overview of the existing literature to provide objective insights as to how lighting induces visual fatigue and related psychophysiological effects occurring in VDT users. In this way, the author points out the applicability of the findings of the existing literature for the implementation of visual fatigue as an indicator to be used in a broader sense; which may be implemented as a key component on identifying visual and non-visual effects of lighting conditions in VDT workstations having different design parameters.