Collective term for the reduction of visual performance or the impairment of perception due to high luminances or luminance contrasts in the visual surroundings. A distinction is made between discomfort glare and disability glare: the former concerns an objective reduction in vision and the latter a subjective impairment due to any disparity between the luminance and information content of the observed area. The glare can be caused by the lamp itself (direct glare) or by reflection of the lamp (reflected glare).