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Andrew Carter Freedman, Gordon E Legge, Jacob Achtemeier; Effect of Enhanced Lighting on the Salience of Environmental Targets with Reduced Acuity. Invest. Ophthalmol. Vis. Sci. 2019;60(9):1827. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Prior work in our lab has shown that subjects with low vision or artificially reduced acuity miss numerous targets when asked to identify all targets while walking through a cluttered indoor environment. Luminance has been proposed as a key factor in environmental target detection for people with low vision, but few studies have examined how enhancing the illumination of specific targets affects their saliency. The current study aimed to determine whether enhanced lighting improves detection of frequently missed targets while subjects walk through a novel indoor environment with simulated acuity restriction.
Subjects walked along an indoor path, guided by a rope line. They were instructed to look for objects, placed at unpredictable intervals left and right of the path, and to describe their size and shape. There were 16 polystyrene objects, either 2 or 4 feet in height, cylindrical or box shaped, and painted white or grey. Lighting varied across targets: those illuminated by ambient overhead lighting served as controls, while other targets were enhanced by additional lighting via spotlights. Spotlights increased luminance of enhanced targets to 3 times their ambient luminance. 20 normally sighted subjects completed testing while wearing blur goggles, which artificially restricted their acuity to 1.65 logMAR. Performance was measured by proportion of targets detected for the two illumination conditions – ambient overhead lighting and ambient lighting plus spotlight enhancement.
There was a significant interaction between object type and illumination, F(2, 38) = 6.811, p = .003, such that illumination improved detection of some targets, but not others. Detection rate of 2 foot tall, white targets was significantly increased by 25.9% (F(1, 19) = 5.39, p < .0005, 95% CI = 15.8-35.9%), and detection of 4 foot tall, white targets was significantly increased by 16.3% (F(1, 19) = 5.04, p < .0005, 95% CI = 9.5-23%). However, detection of grey targets was not significantly increased.
Our initial hypothesis, that increasing luminance of a target would improve detection of that target, regardless of its size, shape, or color, was not confirmed. Our data suggest that while focusing light on some targets will improve their visibility, other factors such as target color play a major role. Therefore, enhanced illumination is not a universal solution for improving target detection.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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