The effect of discomfort glare on parallel processing of visual information

• Published in: Acta ophthalmologica (Oxford, England) Vol. 90; no. s249
• Main Authors: BARGARY, G, BARBUR, JL
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.09.2012; Wiley Subscription Services, Inc
• Subjects: Ergonomics; Ophthalmology; Parallel processing
• ISSN: 1755-375X; 1755-3768
• DOI: 10.1111/j.1755-3768.2012.4283.x

Purpose When a person is confronted with a bright light source against a dim background, scattered light can cause visual discomfort in addition to reducing object contrast on the retina. Previous work addressing the effect of glare on visual performance has focused mainly on the reduction in retinal image contrast (known as disability glare) rather than the often accompanying experience of discomfort glare. This study examines how parallel processing of visual information is affected under conditions of discomfort glare. Methods Light scatter sources surrounded a monitor on which the subject carried out standard contrast acuity (CA) tasks. All CA tasks were carried out with and without discomfort glare (estimated in a prior experiment). In the parallel task, a fovea target (Landolt C) and four peripheral stimuli (three distractors and one target) were presented concurrently; the subject had to indicate both the orientation of the gap for the foveal target and the quadrant containing the peripheral target. The size of the peripheral target was increased relative to the foveal target to ensure that all targets were equally detectable. This was done separately with and without discomfort glare, thus negating any influence of disability glare. Results The presence of discomfort glare degrades visual performance in the parallel processing task even when adjustments are made to cancel out the effects of disability glare. Conclusion Studies that have focused only on disability glare may be underestimating the adverse effect glaring light sources can have on visual performance, particularly in real world scenarios where attention to objects in both the fovea and periphery is often required.