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G. A. Zikos, R. J. Nason, J. Robilotto, A. Selenow; Contrast Sensitivity and Reaction Times with Polarized and Tinted Lenses in a Driving Environment. Invest. Ophthalmol. Vis. Sci. 2009;50(13):5331.
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© ARVO (1962-2015); The Authors (2016-present)
To compare the contrast sensitivity function (CSF) and reaction times (RT) with equal absorption polarized (P) and tinted (T) anti-reflection (AR) coated sunglasses in a simulated daytime driving environment.
Subjects were tested wearing the two plano sunglasses with AR while seated behind a car windsheld and a simulated dashboard. 10 klux illuminance was created by using two 1000W halogen lights to simulate mid-morning/-afternoon lighting conditions. CSF was tested by measuring thresholds with a combination of contrast and resolution targets using a tumbling "E" with contour interaction bars at a test distance of 6M. The Cambridge Research Systems Ltd. ViSaGe on a SONY GDM-F20 CRT was used to conduct a four-alternative forced choice linear staircase procedure. Reaction times were calculated by using the correct responses at threshold level. The subjects were optimally corrected with contact lenses and tested binocularly. Twenty-two normal subjects (19F, 3M), optimally corrected with contact lenses, were tested binocularly. The mean age of the sample was 26 years. Twenty one of the subjects were myopic (+3.00D to -8.75D, Mean=-3.60D).
Polarizing lenses were found to provide both improved contrast and reaction times during simulated daylight driving conditions. The area under the CSF was 20% larger for the Polarized lenses (1.41 vs. 1.13, p<0.01).The effect was not spatial frequency dependent. Reaction times were up to 15% shorter with Polarized lenses (mean RT: P=1164 ms, T=1232ms; p<0.05). Reaction times were found to increase with decreasing contrast by 240ms/log unit of Contrast across both lens conditions.
Contrast sensitivity and reaction times can be significantly improved by using polarized sunglasses when driving in daytime. This result has implications in respect to driving comfort and safety and it may particularly apply in patients with decreased contrast sensitivity (from cataracts or other conditions).
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