THE EFFECT OF TRANSIENT GLARE ON OBJECT-RECOGNITION

Melnick Auditorium

Objective. To investigate how object-recognition is affected by transient glare. Background. Disability glare happens when a light source causes a diffusive intraocular light scattering, which reduces target visibility and results in functional impairment. Previous studies have mainly focused on how visual acuity and contrast sensitivity is affected by steady glare source. However, in real world, most glare sources are transient in nature with sudden onset, such as the headlight of approaching car. Moreover, it is not clear how complex visual functions are affected by transient glare. In this study, we studied how object-recognition is affected by transient glare and provided evidences that veiling luminance, which is mechanism of visual impairment caused by steady glare, may not fully explain the impaired visual performance with transient glare. Methods. The stimulus used is a circular contour deformed by applying a radial sinusoidal modulation to the radius (RF-contour). The center of the glare source was at the same height of the stimulus and deviated horizontally 10° away from the line of sight. The amount of glare and the equivalently reduced retinal contrast (Cst-low) of the stimulus were also calculated. The ability to detect the smallest amount of deformations on circular contours was measured with two-alternative forced choice paradigm under a) test condition: RF-contour at high contrast with a transient glare; b) control 1: RF-contour at high contrast without glare; c) control 2: RF-contour at Cst-low without glare; d) control 3: RF-contour at Cst-low without glare, but with partial section missing. Results. 1. Transient glare significantly impaired the ability to detect the smallest radial deformation in RF contour with high contrast (results a vs. b). 2. The impairment caused by transient glare was significantly greater than those caused by reducing contrast (results a vs. c). 3. The impairment caused by transient glare was similar to those measured at low contrast and with ¼ section missing (results a vs. d). Conclusion. Glare impairs the ability of object recognition. Depending on the configuration of the stimulus and the glare source, this impairment may not be fully explained by veiling luminance. Grants. PFRDG2012