Car Driving Performance in Hemianopia:An On-Road Driving Study

PURPOSE. To study driving performance in people with homonymous hemianopia (HH) assessed in the official on-road test of practical fitness to drive by the Dutch driver's licensing authority (CBR).METHODS. Data were collected from a cohort (January 2010-July 2012) of all people with HH following the official relicensure trajectory at Royal Dutch Visio and the CBR in the Netherlands. Driving performance during the official on-road tests of practical fitness to drive was scored by professional experts on practical fitness to drive, using the visual impairments protocol and a standardized scoring of visual, tactical and operational aspects. Age ranged from 27 to 72 years (mean = 52, SD = 11.7) and time since onset of the visual field defect ranged from 6 to 41 months (mean = 15, SD = 7.5).RESULTS. Fourteen (54%) participants were judged as fit to drive. Besides poor visual scanning during driving, specific tactical, and operational weaknesses were observed in people with HH that were evaluated as unfit to drive. Results suggest that judgement on practical fitness to drive cannot be based on solely the visual field size. Visual scanning and operational handling of the car were found to be more impaired with longer time not driven, while such an effect was not found for tactical choices during driving.CONCLUSIONS. Training programs aimed at improving practical fitness to drive in people with HH should focus on improving both visual scanning, as well as driving aspects such as steering stability, speed adaptation, and anticipating environmental changes.</p

Assessing fitness to drive:A validation study on patients with mild cognitive impairment

Objectives: There is no consensus yet on how to determine which patients with cognitive impairment are able to drive a car safely and which are not. Recently, a strategy was composed for the assessment of fitness to drive, consisting of clinical interviews, a neuropsychological assessment, and driving simulator rides, which was compared with the outcome of an expert evaluation of an on-road driving assessment. A selection of tests and parameters of the new approach revealed a predictive accuracy of 97.4% for the prediction of practical fitness to drive on an initial sample of patients with Alzheimer's dementia. The aim of the present study was to explore whether the selected variables would be equally predictive (i.e., valid) for a closely related group of patients; that is, patients with mild cognitive impairment (MCI).Methods: Eighteen patients with mild cognitive impairment completed the proposed approach to the measurement of fitness to drive, including clinical interviews, a neuropsychological assessment, and driving simulator rides. The criterion fitness to drive was again assessed by means of an on-road driving evaluation. The predictive validity of the fitness to drive assessment strategy was evaluated by receiver operating characteristic (ROC) analyses.Results: Twelve patients with MCI (66.7%) passed and 6 patients (33.3%) failed the on-road driving assessment. The previously proposed approach to the measurement of fitness to drive achieved an overall predictive accuracy of 94.4% in these patients. The application of an optimal cutoff resulted in a diagnostic accuracy of 100% sensitivity toward unfit to drive and 83.3% specificity toward fit to drive. Further analyses revealed that the neuropsychological assessment and the driving simulator rides produced rather stable prediction rates, whereas clinical interviews were not significantly predictive for practical fitness to drive in the MCI patient sample.Conclusions: The selected measures of the previously proposed approach revealed adequate accuracy in identifying fitness to drive in patients with MCI. Furthermore, a combination of neuropsychological test performance and simulated driving behavior proved to be the most valid predictor of practical fitness to drive.</p

The Introduction of Bioptic Driving in the Netherlands

Background: In many US states, people with moderately reduced visual acuity (eg, 20/50–20/200) can legally drive with the aid of a small, spectacle-mounted (“bioptic”) telescope.We conducted a demonstration project to assess the viability of implementing bioptic driving in the Netherlands. In this article, we describe the framework of the project from conception through to realization of our primary objective—the introduction of bioptic driving as a legal option for visually impaired people in the Netherlands. Methods: The project was based on bioptic driving programs in the United States, which were adapted to fit into current driving training and assessment practices in the Netherlands. The project convened a consortium of organizations including the Netherlands Bureau of Driving Skills Certificates, service organizations for the visually impaired, and research departments at universities investigating driving and vision. All organizations were educated about bioptic driving and participating professionals were trained in their specific aspects of the project. Media publicity led to significant interest and helped recruitment that enabled the screening and selection of potential participants. Outcomes: The project demonstrated that people with moderately reduced visual acuity can be trained to achieve an adequate level of proficient and safe driving (as assessed by the local official driving licensing professionals) when using a bioptic telescope for the road conditions in the Netherlands. Based on the successful project outcomes, a request was made to the minister to allow bioptic driving in the Netherlands. This request has been accepted; the legal procedures for implementation are in process

Compensatory viewing training improves practical fitness to drive of subjects with impaired vision

In many countries strict legal requirements for obtaining a driver’s license are in effect for visual acuity and visual field.We studied the relationship between these characteristics and driving safety and driving proficiency in an on-the-road test of practical fitness to drive in subjects with visual disorders, including many subjects scoring below current criteria. We further studied how far the relationship between the on-the-road test and visual measures improved if compensatory eye movements and visual attention were included in the criteria. Lastly, we studied the effects of training compensatory viewing strategiesformed the on-the-road test before and after training. Training consisted of laboratory and mobility training, including driving instruction. Visual function assessment included acuity, visual field, contrast sensitivity, visual attention, compensatory viewing efficiency, and visuospatial tests. In one study an advanced driving simulator was used besides the on-the-road assessment. Two models were compared to predict the on-the-road score. Results: 13–62% of the subjects passed the on-the-road test before training. After training, an additional 15–45% passed. The power of both models to predict the on-the-road score rose to about 45% by adding viewing behavior in the driving simulator. Discussion: A considerable percentage of the subjects, legally not allowed to drive, passed the on-the-road test. Sensitivity and specificity of vision tests and driving simulator tests are still too low to decide upon unfitness to drive. Training of compensatory viewing improved the performance in the on-the-road test

A Demonstration Project on Driving with Reduced Visual Acuity and a Bioptic Telescope System in the Netherlands

Background: In Europe, driving a passenger car is prohibited if binocular best corrected visual acuity (BCVA) is below 0.5 (20/40). Some US states allow people with reduced visual acuity to use a bioptic telescope system when driving. The aim of our study is to introduce a bioptic telescope system for driving in the Netherlands and to investigate whether it enables people with reduced visual acuity to gain sufficient practical fitness to drive in a European setting. Results:Out of 378 persons who applied for information following media attention for the project, 160 candidates volunteered to participate. Based on the available information, 36 subjects (binocular BCVA: 0.16–0.5 [20/125–20/40]) were invited for assessment (vision, mobility, cognitive function, and driving skills). Of these, 16 did not meet the inclusion criteria and 2 decided not to participate. The remaining 18 subjects were trained in the use of a monocular bioptic telescope (3×magnification). They all completed the predriving training successfully and received driving lessons from specialized professional driving instructors. Eventually, 9 subjects passed the official on-road test of practical fitness to drive, 7 were excluded after a number of driving lessons, and another 2 withdrew on their own initiative. Conclusion: This is the first study in Europe to prepare subjects with reduced visual acuity to drive with the use of a bioptic telescope system. About 55% of the preselected subjects fulfilled all inclusion criteria. Half of the subjects who entered the bioptic training program passed the official fitness to drive test, demonstrating that they could drive smoothly and safely in Dutch traffic using a bioptic telescope system.