Driving behaviour and visual compensation in glaucoma patients: Evaluation on a driving simulator.

BACKGROUND: To assess the driving performance and both the visual scanning and driving compensations of glaucoma patients. METHODS: In this case-control pilot study, the driving behaviour and performance of 14 patients with glaucoma and nine healthy age- and sex-similar control subjects were compared in a fixed-base driving simulator. All subjects performed in four scenarios with one to two hazardous situations on urban streets, for a total of five hazards. Measurements taken during the tests included reaction times, longitudinal regulation, lateral control and eye and head movements. RESULTS: Glaucoma patients showed poor driving performance with longer reaction time to hazardous situations than control subjects: pedestrians crossing the road from the left (p < 0.022) or from the right (p = 0.013), and vehicles coming from the left (p = 0.002). Their mean duration of lateral excursion was longer (p = 0.045), and they showed more lane excursions in a wide left curve (p = 0.045). Glaucoma patients also showed a higher standard deviation of time-headway (p = 0.048) with preceding vehicles. Analyses of driving behavioural compensations on curved roads showed that glaucoma patients stayed closer to the centre line in large (p = 0.006) and small (p = 0.025) left curves and on small right curves (p = 0.041). Additionally, on straight roads, as compared to control subjects, glaucoma patients showed longer mean time-headway (p = 0.032) and lower mean speed (p = 0.04). Finally, the glaucoma group exhibited a larger standard deviation of horizontal gaze (p = 0.034) than the control subjects. CONCLUSIONS: In a virtual driving environment, glaucoma patients exhibited unsafe driving behaviours, despite their driving and eye-scanning compensations.

Validation of the driver ecological glare test.

INTRODUCTION: The present study proposes to validate the Driver Ecological Glare Test (DEGT), a test developed to measure the benefit of a headlight glare Advanced Driver Assistance System (ADAS), by comparing it to a laboratory glare test. METHOD: Twenty-four participants, aged from 55 to 70 years, were recruited to complete a visual examination, including monocular halo size measurement for both eyes using Vision Monitor device (MonCv3; Metrovision). An on-field evaluation took place at night at the UTAC CERAM test track to obtain disability glare measures using the DEGT. RESULTS: A significant correlation was found between the two glare tests and Bland-Altman analysis reveals a good agreement with a bias of 73.7 arcmin between the halo size measurements obtained from the DEGT and Vision Monitor. The results of the present study demonstrate that the DEGT is a valid method to test halo size and is adapted to evaluate the benefits of an antiglare device for drivers in an ecological situation.

Implications of monocular vision for racing drivers.

We performed two experiments to investigate how monocular vision and a monocular generalized reduction in vision (MRV) impact driving performance during racing. A total of 75 visually normal students or professional racing drivers, were recruited for the two experiments. Driving performance was evaluated under three visual conditions: normal vision, simulated monocularity and simulated monocular reduction in vision. During the driving scenario, the drivers had to detect and react to the sudden intrusion of an opponent's racing car into their trajectory when entering a turn. Generalized Linear Mixed Models (GLMMs) and ANOVA were then used to explore how monocular vision and monocular reduction in vision affect drivers' performance (crash and reaction time) while confronting them with critical situations. The results show that drivers under monocular condition are from 2.1 (95% CI 1.11-4.11, p = .024) to 6.5 (95% CI 3.91-11.13; p = .0001) times more likely to collide with target vehicles compared with their baseline (binocular) condition, depending on the driving situation. Furthermore, there was an average increase in reaction time from 64 ms (p = .029) to 126 ms (p = .015) under monocular condition, depending on the critical driving situation configuration. This study objectively demonstrates that monocularity has a significant impact on driving performance and safety during car racing, whereas performance under monocular reduction in vision conditions is less affected.

Exploring the contribution of executive functions to on-road driving performance during aging: A latent variable analysis.

With the aging of the population the issue of older drivers safety has gained importance in recent years. Age-related cognitive decline is frequently cited as the main cause of unsafe driving performance in older drivers. OBJECTIVE: The present study investigated how executive functions (EFs), measured as latent variables, are related to on-road driving performance during aging. METHOD: One hundred and twenty-six participants aged from twenty to eighty-two, completed a two hundred and forty-seven km on-road driving test and a set of executive tasks selected to tap three often postulated EFs: inhibition (inhibiting prepotent responses), updating (updating working memory representations), and shifting (shifting task sets). RESULTS: Confirmatory factor analysis reproduces previous results obtained by Miyake et al. (2000), Miyake and Friedman (2012) of unity and diversity of EFs in an adult life span sample. Structural equation modeling suggested that on-road driving performance was related to inhibition. Furthermore, findings indicate that the age-related driving performance decline in normal aging may be mediated by the inhibition function. CONCLUSIONS: The results highlight the importance of a proper method to assess executive functioning in a specific domain as well as emphasising the major role of those functions in driving performance while aging.

An Attempt of Early Detection of Poor Outcome after Whiplash.

The main concern with whiplash is that a large proportion of whiplash patients experience disabling symptoms or whiplash-associated disorders (WAD) for months if not years following the accident. Therefore, identifying early prognostic factors of WAD development is important as WAD have widespread clinical and economic consequences. In order to tackle that question, our study was specifically aimed at combining several methods of investigation in the same WAD patients at the acute stage and 6 months later. Our longitudinal, open, prospective, multi-center study included 38 whiplash patients, and 13 healthy volunteers matched for age, gender, and socio-economic status with the whiplash group. Whiplash patients were evaluated 15-21 days after road accident, and 6 months later. At each appointment, patients underwent a neuropsychological evaluation, a full clinical neurological examination, neurophysiological and postural tests, oto-neurological tests, cervical spine cord magnetic resonance imaging (MRI) with tractography (DTI). At 6 months, whiplash patients were categorized into two subgroups based on the results of the Diagnostic and Statistical Manual of Mental Disorders as having either favorable or unfavorable progression [an unfavorable classification corresponding to the presence of post-concussion symptom (PCS)] and we searched retrospectively for early prognostic factors of WAD predicting the passage to chronicity. We found that patients displaying high level of catastrophizing at the acute stage and/or post-traumatic stress disorder associated with either abnormalities in head or trunk kinematics, abnormal test of the otolithic function and at the Equitest or a combination of these syndromes, turned to chronicity. This study suggests that low-grade whiplash patients should be submitted as early as possible after the trauma to neuropsychological and motor control tests in a specialized consultation. In addition, they should be evaluated by a neuro-otologist for a detailed examination of vestibular functions, which should include cervical vestibular evoked myogenic potential. Then, if diagnosed at risk of WAD, these patients should be subjected to an intensive preventive rehabilitation program, including vestibular rehabilitation if required.

Personality traits and executive functions related to on-road driving performance among older drivers.

The present study investigated how executive functions and personality traits are related with driving performance among older drivers. Forty-two participants aged 60 and over were recruited to complete a battery of cognitive tests, measures of personality traits and an on-road driving test. Significant correlations were found between poor driving performances and low scores on tests assessing shifting and updating functions. In addition, extraversion had a negative relation with driving performance and made the only contribution, among the psychological factors, to the prediction of driving performance. Finally, gender and age emerged as the best predictors of on-road driving performance. Gender, personality traits and executive functions should be taken into account when studying safety among older drivers.