Purpose: People with moderate central vision loss are legally permitted to drive with a bioptic telescope in 39 US states and the Netherlands, but the safety of bioptic driving remains highly controversial. There is no scientific evidence about bioptic use and its impact on safety. We propose searching for evidence by recording naturalistic driving activities in patients ’ cars. Methods: In a pilot study we used an analogue video system to record two bioptic drivers ’ daily driving activities for 10 and 5 days, respectively. In this technical report, we also describe our novel digital system that collects vehicle manoeuvre information and enables recording over more extended periods, and discuss our approach to analyzing the vast amount of data. Results: Our observations of telescope use by the pilot subjects were quite different from their reports in a previous survey. One subject used the telescope only seven times in nearly 6 h of driving. For the other subject, the average interval between telescope use was about 2 min, and Mobile (cell) phone use in one trip extended the interval to almost 5 min. We demonstrate that computerized analysis of lengthy recordings based on video, GPS, acceleration, and black box data can be used to select informative segments for efficient off-line review of naturalistic driving behaviours. Conclusions: The inconsistency between self reports and objective data as well as infrequent telescope use underscores the importance of recording bioptic driving behaviours in naturalistic conditions over extended periods. We argue that the new recording system is important for understanding bioptic use behaviours and bioptic driving safety.

Abstract—Visually impaired people may legally drive if wearing bioptic telescopes in some developed countries. To address the controversial safety issue of the practice, we have developed a low-cost in-car recording system that can be installed in study participants’ own vehicles to record their daily driving activities. We also developed a set of automated identification techniques of informative behaviors to facilitate efficient manual review of important segments submerged in the vast amount of uncontrolled data. Here, we present the methods and quantitative results of the detection performance for six types of driving maneuvers and behaviors that are important for bioptic driving: bioptic telescope use, turns, curves, intersections, weaving, and rapid stops. The testing data were collected from one normally sighted and two visually impaired subjects across multiple days. The detection rates ranged from 82 % up to 100%, and the false discovery rates ranged from 0 % to 13%. In addition, two human observers were able to interpret about 80 % of targets viewed through the telescope. These results indicate that with appropriate data processing the low-cost system is able to provide reliable data for natural bioptic driving studies. Index Terms—Bioptic driving, driving behavior, instrumented vehicle, natural driving study.