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Bradley E Dougherty, Amber Mathias, Roanne E. Flom, Thomas Kerwin, Thomas W Raasch; The Effect of Bioptic Telescopic Spectacle Use on Road Sign Recognition in Drivers with Central Vision Impairment. Invest. Ophthalmol. Vis. Sci. 2016;57(12):1964.
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© 2017 Association for Research in Vision and Ophthalmology.
People with central vision impairment may be licensed to drive with bioptic telescopic spectacles (BTS) in most US states. However, questions remain about whether BTS should be required for licensure, and whether their use improves driving performance. This study uses a driving simulator to compare both road sign recognition distances and rates of sign recognition failure with and without use of BTS.
Bioptic drivers and controls were recruited from the College of Optometry at the Ohio State University. ETDRS visual acuity and Mars chart contrast sensitivity were measured. The driving portion of the study was performed on a six degree-of-freedom driving simulator with a 260° curved front screen, side mirror LCD displays and a screen seen through the rear-view mirror. The course was a straight four-lane highway with light traffic and a 45mph speed limit. Subjects completed two ~30-minute courses (for bioptic drivers, one with the BTS and one with the telescope occluded), and were instructed to press a button on the steering wheel when able to confidently identify signs with a target city name or route number among distractor signs. T-tests were used to analyze differences in mean recognition distances.
Eleven bioptic drivers and 6 controls participated. Mean±SD age was 53±18 years for bioptic drivers and 52±9 for controls. Mean logMAR VA OU for bioptic drivers was 0.82±0.16 (20/132) and mean log CS was 1.63±0.15. Mean VA with telescope was 0.23±0.09 (20/34). There was a significant increase in distance at sign recognition with BTS use (mean 144±69 m vs. 51±36 m, p<0.001) that was moderately well predicted by level of telescope magnification. Control driver recognition distances (239±58 m) were higher than for bioptic drivers with BTS (p<0.003). Rates of sign recognition failure were: control = 0.9%, bioptic driver with BTS = 2.7%, bioptic driver without BTS = 6.4%.
The distance at which road signs could be identified increased with use of BTS, though there was considerable variation in effectiveness of BTS use between drivers. There were fewer sign recognition failures with use of BTS in bioptic drivers.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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