Visual discomfort and glare assessment in office environments: A review of light-induced physiological and perceptual responses

Lighting in office environments has many benefits, ranging from decreasing energy consumption to enhancing human health and well-being. However, visual discomfort such as glare has a negative impact on occupants, causing a sensation of annoyance or pain, thereby reducing user satisfaction and productivity. Current methods and metrics established for evaluating glare are mainly derived from physical measurements of luminance distribution and conventional subjective evaluations. However, significant inconsistencies and inaccuracies reported by a number of comparative studies highlight the need for a more objective method in the derivation of glare indices. This paper reviews the existing literature to provide a holistic overview of implemented methods in measuring light-induced physiological responses to objectify perceived glare. Physiological responses investigated within the reviewed literature include: pupil size, eye movement, gaze direction, degree of eye-opening, and blink rate. Research outcomes regarding each individual response are then analysed based upon their experimental methodology, the metric utilized for their analysis, and confounding variables that may contribute to misleading results. Through this analysis, established factors and those requiring further evidence are identified.