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Asad Farooq Durrani, Ervin Sejdic, Thomas R Friberg; Adopting contrast sensitivity screening in a drivers license program: Results from a pilot study of 346 subjects. Invest. Ophthalmol. Vis. Sci. 2019;60(9):1391.
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© ARVO (1962-2015); The Authors (2016-present)
Contrast sensitivity measurement provides details about functional vision not captured by visual acuity testing, however, it is not commonly tested when obtaining a driver’s license. This study occurred at 6 centers across Pennsylvania and tested contrast sensitivity in drivers and analyzed its association with age and historical accident data.
346 drivers were enrolled. In order to test contrast sensitivity, subjects were asked to identify the orientation of a series of lines as right, up, or left (Figure 1). 5 blocks of increasing difficulty were tested (A, B, C, D, E), each containing 4 images. Failure was defined as more than 2 errors in a block. Age, sex, visual acuity, visual field test scores, history of traffic offenses, and history of accidents were collected. Logistic regression was used to assess if these variables correlated with errors made during sensitivity testing.
111 subjects were under 35 years old, 114 were between 35-50 years old, and 121 were over 50 years old. In the most challenging blocks of testing (Blocks D and E), the mean number of errors increased with age (Table 1). Failure rates in these blocks were as follows: 17.12% and 25.23% of those under 35, 8.77% and 16.67% between 35-50, and 19.83% and 23.14% over 50. Regarding accidents, 23.03% of subjects under 35, 49.12% between 35-50, and 37.19% had a previous incident. Logistic regression demonstrated age (p<0.0001) and corrected vision (p=0.0002) were correlated with the number of errors in Blocks D and E. History of accident was not correlated with number of errors.
As the difficulty of sensitivity testing increased, the mean number of errors increased in an age dependent manner. In the final two blocks of testing, the number of errors in subjects over 50 was 4.5-5 times higher than for those under 35 and 1.4-1.7 times higher than for those between 35-50. Interestingly, those with more errors were not found to have higher incidence of accidents, though, this study only used historical accident data. Our study suggests a significant portion of drivers have issues with contrast sensitivity, especially those over 50. Further studies are needed to determine the role of contrast sensitivity in the incidence of accidents and to develop cutoffs for contrast sensitivity testing.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
Pattern and Booklet Used In Testing
Testing Error Data By Age Group
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