Visual function correlates of self-reported vision-related nighttime driving difficulties

Vofo B.N., Ayuk D.A., Pe’er J., Chichom-Mefire A., Tendongfor N., Nche E.N.

Driving is a visually intensive task. In Cameroon, where the burden of road traffic deaths is high, visual assessment is not universally performed before the issuance of driver licenses. This study aims to assess the visual status of commercial drivers (CDs) in the southwestern region of Cameroon, and to find its relation to road traffic crashes (RTCs). This work was a cross-sectional community-based study on CDs in Limbe and Buea. Questionnaires were used to assess sociodemographic parameters, the incidence of RTCs, and self-reported visual status. Visual acuity (VA) was measured using a standard Snellen chart at 6 m. Statistical analysis was performed using descriptive methods: frequencies, the paired Student’s t-test, and the chi-square test. Two hundred seven CDs were enrolled in this study, all of which were male, with a mean age of 41.8 ± 12.1 years. A total of 15.0% had undergone an eye exam prior to licensure, and 3.4% had undergone an eye exam within the past 10 years. The VA in the better-seeing eye of participants was less than 6/9 and 6/12 in 14.1 and 10.6% of CDs, respectively. Seventy-five percent of CDs with self-reported poor vision and 95% of CDs with VA < 0.5 had a history of RTCs compared to 55.8% of CDs with self-reported good vision and 55.7% of CDs with VA ≥ 0.5 (p < 0.05). Injuries from RTCs were more common in CDs with self-reported poor vision (81.1%) and in those with VA < 0.5 (90.5%) compared to CDs who self-reported good vision (55.8%) and those with VA ≥ 0.5 (55.7%) (p < 0.05). A large proportion of CDs did not undergo a visual assessment before the issuance or renewal of their driver licenses. A substantial number of CDs had poor vision in their better-seeing eye and suffered from RTCs and related injuries, which suggests that the visual status of CDs in Cameroon is related to the gruesome number of road traffic crashes and deaths in the country. Therefore, concerned authorities should consider making vision tests a necessary requirement for the obtention of driver licenses.

Sangkharat K., Thornes J.E., Wachiradilok P., Pope F.D.

The World Health Organization has highlighted that the number of deaths worldwide due to road accidents increases every year. It recommends that countries improve road safety for all people by providing sustainable and safe transport systems by 2030, efforts are especially required within Low Middle-Income Countries (LMICS). This study is the first to investigate the impact of rainfall on road accidents in Thailand. Thai emergency data were collected from the National Institute for Emergency Medicine (NIEM) between 2012 to 2018. A time-series design with generalized linear model (GLM) was applied to analyse the associations between road accidents and rainfall. The results are reported using relative risk (RR) at 95% confidence intervals compared with dry days. The effects of long-term trends, seasonality, day of the weeks, public holidays and other meteorological factors were controlled in the GLM. A meta-analysis was applied to summarise the estimate effect of rain groups stratified by the Northern and Southern provinces. Findings reported a significant increase in road accidents due to high rainfall levels both in the Southern and the Northern provinces. The pooled estimate risks in the Southern provinces have higher estimated risks than the Northern provinces. Both Northern and Southern provinces showed the rain group with 10-20 mm/day having the highest pooled estimated risk with RR = 1.052, (95% CI: 1.026-1.079) and RR = 1.062, (95% CI: 1.043-1.082), respectively, while surprisingly, heavy rain with more than 20 mm/day reported a reduction of risks. Road accidents can therefore be associated with rainfall. It is recommended that rainfall is factored into ambulance forecast models and warning systems, allowing for improvements in ambulance service efficiency. Policymakers need to integrate road safety policies that reduce road accidents in wet weather.

Boadi‐Kusi S.B., Austin E., Abu S.L., Holdbrook S., Morny E.K.

Glare caused by the headlights of on-coming vehicles risk safe driving at night. The study aimed to determine the relationship between glare exposure and nighttime driving performance among commercial drivers in Ghana.This cross-sectional study involved commercial drivers with complaints of nighttime driving difficulties (N = 80; mean age = 41.5 ± 11.1 years). A questionnaire was used to investigate nighttime driving performance following glare exposure. We measured contrast sensitivity and visual acuity under photopic conditions. With an experimental setup in a mesopic setting, we measured visual acuity with and without glare exposure. The difference between the two mesopic visual acuities was quantified as disability glare index. With the same setup, photostress recovery time was also measured. Regression analyses were used to determine the relationship between nighttime driving performance score and the measures taken in both photopic and mesopic settings.The average nighttime driving performance score was 47.8 ± 17.5. Driving performance was negatively correlated with all variables (R = -0.87 to -0.30, all p < .01), except contrast sensitivity (R = 0.74, p < .01). A multiple linear regression showed that the model with all variables explained 83.8% of the variance, but only disability glare index was a significant predictor of nighttime driving performance following glare exposure (standardized B = -0.61, p < .01).Our results show that the change in mesopic visual acuities following glare can predict nighttime driving performance. This measure can be incorporated into the assessment of driving fitness by licensing departments to evaluate whether a person can drive safely at night amidst glare exposure.

Ackaah W., Apuseyine B.A., Afukaar F.K.

The study was to examine the nature and risk factors associated with road traffic crashes at night in Ghana and identify potential measures to control them. Crash and injury data for the period 201...

Wood J.M.

Purpose : Nighttime driving is dangerous and is one of the most challenging driving situations for most drivers. Fatality rates are higher at night than in the day when adjusted for distances travelled, particularly for crashes involving pedestrians and cyclists. Although there are multiple contributory factors, the low light levels at night are believed to be the major cause of collisions with pedestrians and cyclists at night, most likely due to their reduced visibility. Understanding the visibility problems involved in nighttime driving is thus critical, given the increased risk to road safety. Recent Findings : This review discusses research that highlights key differences in the nighttime road environment compared to the day and how this affects visual function and driving performance, together with an overview of studies investigating how driver age and visual status affect nighttime driving performance. Research that has focused on the visibility of vulnerable road users at nighttime (pedestrians and cyclists) is also included. Summary : Collectively, the research evidence suggests that visual function is reduced under the mesopic lighting conditions of night driving and that these effects are exacerbated by increasing age and visual impairment. Light and glare from road lighting and headlights have significant impacts on vision and night driving and these effects are likely to change with evolving technologies, such as LED streetlighting and headlights. Research also highlights the importance of the visibility of vulnerable road users at night and the role of retroreflective clothing in the ‘biomotion’ configuration for improving their conspicuity and hence safety.

Kimlin J.A., Black A.A., Wood J.M.

Purpose: To investigate associations between older drivers' perceived vision-related night-driving difficulties and night-time driving performance measured on a closed-road circuit. Methods: Participants included 26 older drivers (71.8 ± 6.3 years) who reported vision-related night-driving difficulties assessed with the vision and night driving questionnaire (VND-Q). High-contrast, photopic visual acuity (VA) and ratings of discomfort glare (de Boer scale) were also assessed. Night-time driving performance was measured on a closed-road circuit that involved recognition, hazard avoidance and lane-keeping tasks in the absence and presence of intermittent glare. Generalized linear mixed models investigated the relationship between VND-Q scores and overall driving performance scores, as well as with discomfort glare ratings and VA. Results: Greater levels of vision-related night-driving difficulties (VND-Q scores) were significantly associated with poorer night-driving performance (p = 0.003); the association was even stronger for driving performance in the presence of intermittent glare (p = 0.001). Reduced VA was associated with poorer night-driving performance (p = 0.022) but the association was weaker than for the VND-Q scores. In contrast, ratings of discomfort glare were not significantly associated with driving performance (p = 0.14). Conclusion: The VND-Q was significantly associated with night-time driving performance and provides a useful instrument for assessing vision-related night-driving difficulties which can be incorporated into clinical vision assessments.

Merickel J., High R., Dawson J., Rizzo M.

Objective: This study addresses the need to measure and monitor objective, real-world driver safety behavior in at-risk drivers with age-related dysfunction. Older drivers are at risk for age-related cognitive and visual dysfunction, which may reduce mobility and increase errors that lead to crashes. Understanding patterns of real-world behavior, exposure, and cognitive-perceptual processes underlying risk in environmental context and in older drivers requires new approaches.Methods: We assessed patterns of objective, real-world driver risk exposure and vehicle control related to steering, braking, and accelerating in older adults with a range of cognitive and visual functional abilities. Real-world driver behavior was collected from passive-monitoring systems installed in 77 drivers' vehicles and analyzed across 242,153 km (150,467 miles) driven. Driver behavior was assessed cross-sectionally in relationship to driver functional abilities and safety-critical environmental contexts (roadway type and visibility condition).Results: Results suggest that cognitive dysfunction impairs vehicle control across wide-ranging environments. Drivers with greater cognitive dysfunction showed more erratic braking and accelerating during daytime commercial and interstate driving. Drivers with less cognitive dysfunction showed more erratic braking and accelerating on residential roadways regardless of visibility condition. Greater cognitive dysfunction predicted more erratic steering on commercial and interstate roadways and less erratic steering on residential roadways. Greater visual dysfunction impaired braking and accelerating during nighttime and interstate driving, but not on residential or commercial roadways. Steering behavior was unaffected by visual abilities. Drivers with greater cognitive dysfunction did not appear to reduce driving frequency in higher-risk environments. Visually impaired drivers drove more on residential roadways and less on commercial roadways, but did not reduce driving on interstates, where they showed the greatest risk per mile driven.Conclusions: Results successfully mapped driver cognitive and visual profiles onto contemporaneous, real-world behavior and risk loci. Results link age-related dysfunction to real-world vehicle control and show that drivers may not sufficiently reduce exposure to higher-risk driving environments. Employing naturalistic observation to monitor and measure patterns of driver behavior can inform methods for early detection of age-related risk, fitness-to-drive assessments, and interventions to preserve safety, mobility, and quality of life in aging or other at-risk populations.

Kimlin J.A., Black A.A., Wood J.M.

To examine the associations between nighttime driving performance of older drivers and photopic, mesopic, and glare-based tests of visual function.Participants included 26 older drivers (71.8 ± 6.3 years), with minimal or no eye disease, but who reported vision-related nighttime driving difficulties. Nighttime driving performance was assessed on a closed-road circuit, which included intermittent glare. An overall driving performance score was calculated based on detection of signs, pedestrians, wooden animals and road markings, lane-keeping, and avoidance of low contrast hazards. Visual function tests included photopic and mesopic visual acuity (VA) and contrast sensitivity (CS). Tests of glare (Berkeley Glare and Aston Halometer) and mesopic motion sensitivity were also assessed. Regression analyses were used to explore the associations between these vision measures and nighttime driving performance.The overall driving performance score was significantly reduced by intermittent glare (P = 0.002); notably, pedestrian detection decreased by 38% in the presence of intermittent glare (P < 0.001). Overall driving scores were most strongly associated with motion sensitivity (P = 0.001) and mesopic high contrast VA (P = 0.002), rather than photopic or glare-based tests. Motion sensitivity accounted for more than twice the variation in driving performance compared to photopic high contrast VA (29% vs. 14%).Glare reduced several aspects of nighttime driving performance. Mesopic tests of visual function, including motion sensitivity and mesopic high contrast VA, were more strongly associated with nighttime driving performance than photopic high-contrast VA. These results highlight the potential importance of nonstandard vision tests for assessing older drivers' visual capacity to drive at night.

Tyrrell R.A., Wood J.M., Owens D.A., Whetsel borzendowski S., Stafford sewall A.

Kimlin J.A., Black A.A., Djaja N., Wood J.M.

Night-time driving difficulties are a common concern of older drivers and those with eye disease. This study aimed to develop and validate a questionnaire for assessing vision-related night driving difficulties in older drivers.Items from existing vision-related quality of life questionnaires and driving studies were used to develop a questionnaire that was completed by 283 participants who reported visual difficulties for night driving (65% female, 50 to >80 years). The questionnaire included items relating to demographic and night driving characteristics (seven items), general vision ratings (eight items), vision-related night driving difficulties (11 items), and a single open question about specific night driving difficulties. The vision-related night driving difficulty items were analysed separately using Rasch analysis to form the vision and night driving questionnaire (VND-Q). Rasch analysis assessed validity and psychometric properties of the scale. Generalised linear regression models examined associations between VND-Q scores and age, gender, amount of night driving, self-rated vision, and eye conditions. Test-retest repeatability was assessed using intra-class correlation analysis and Bland-Altman methods of agreement for a subset of 30 participants.Rasch analysis indicated that a nine-item VND-Q scale was unidimensional, valid and reliable, and showed excellent discriminant ability (person separation index 3.04; person reliability 0.90). Targeting was better for those with greater self-reported night driving difficulties. Participants with self-reported bilateral eye conditions and worse self-reported general vision ratings had significantly more night driving difficulties with the VND-Q scale than individuals without eye conditions (p = 0.03) and with better general vision ratings (p < 0.001). Females reported more difficulties than males (p < 0.001) and drove shorter distances at night per week which was also associated with greater difficulties (p < 0.001). A repeatability coefficient (Rc ) of 2.07 demonstrated excellent test-retest repeatability.The nine-item VND-Q is a unidimensional and reliable questionnaire allowing quantification of the level of visual difficulties that older drivers report at night. The development of this questionnaire is an important step in providing a reliable and validated instrument for use to guide appropriate investigations, referrals, or interventions in clinical and research settings.

Boadi-Kusi S.B., Kyei S., Asare F.A., Owusu-Ansah A., Awuah A., Darko-Takyi C.

To determine the relationship between some visual functions: colour vision defects, abnormal stereopsis, visual acuity and the occurrence of road traffic accident (RTAs) among commercial vehicle drivers in the central region of Ghana, and to assess their knowledge of these anomalies.A descriptive cross-sectional study employing a multi-stage random sampling approach was conducted in the major commercial towns within the central region of Ghana. Participants were taken through a comprehensive eye examination after the administration of a structured questionnaire.520 male commercial vehicle drivers were enrolled for this study with a mean age of 39.23 years ±10.96 years and mean visual acuity of 0.02±0.08 logMAR. Protans were more likely to be involved in RTAs (χ(2)=6.194, p=0.034). However, there was no statistically significant association between abnormal stereopsis (OR=0.89 95% CI: 0.44-1.80, p=0.56), poor vision due to refractive error (χ(2)=3.090, p=0.388) and the occurrence of RTAs. While 86.9% were aware of abnormal stereopsis, only 45% were aware of colour vision defects. There was a statistically significant association between stereopsis anomaly and colour vision defect (r=0.371, p

Wood J.M., Marszalek R., Lacherez P., Tyrrell R.A.

This study investigated whether the night-time conspicuity of road workers can be enhanced by positioning retroreflective strips on the moveable joints in patterns that convey varying degrees of biological motion. Participants were 24 visually normal adults (12 young M=26.8 years; 12 older M=72.9 years). Visual acuity, contrast sensitivity and glare sensitivity were recorded for each participant. Experimenters acting as road workers walked in place on a closed road circuit within simulated road work sites, facing either the oncoming driver or the roadway (presenting sideways to the driver) and wearing one of four clothing conditions: (i) standard road worker vest; (ii) standard vest plus thigh-mounted retroreflective strips; (iii) standard vest plus retroreflective strips on ankles and knees; (iv) standard vest plus retroreflective strips positioned on the extremities in a configuration that conveyed biological motion ("biomotion"). As they drove along the closed road participants were instructed to press a button to indicate when they first recognized that a road worker was present. The results demonstrated that regardless of the direction of walking, road workers wearing biomotion clothing were recognized at significantly (p

Bernardin F., Bremond R., Ledoux V., Pinto M., Lemonnier S., Cavallo V., Colomb M.

Driving through rain results in reduced visual performance, and car designers have proposed countermeasures in order to reduce the impact of rain on driving performance. In this paper, we propose a methodology dedicated to the quantitative estimation of the loss of visual performance due to the falling rain. We have considered the rain falling on the windshield as the main factor which reduces visual performance in driving. A laboratory experiment was conducted with 40 participants. The reduction of visual performance through rain was considered with respect to two driving tasks: the detection of an object on the road (contrast threshold) and reading a road sign. This experiment was conducted in a laboratory under controlled artificial rain. Two levels of rain intensity were compared, as well as two wiper conditions (new and worn), while the reference condition was without rain. The reference driving situation was night driving. Effects of both the rain level and the wipers characteristics were found, which validates the proposed methodology for the quantitative estimation of rain countermeasures in terms of visual performance.

Angkititrakul P., Miyajima C., Takeda K.

Driving context plays an essential role in driving behavior and driving performance of a driver. The contextual information surrounding a driving activity involves several factors and dimensions that influence a driver's behavior. However, a driver may or may not need to adopt a particular driving pattern for every distinct driving context conditions. In this paper, we statistically investigate the impact of various driving context conditions on the behavior prediction and context recognition performance of stochastic driver-behavior models. We employed a Dirichlet process mixture modeling framework to capture the underlying distributions of observed driving parameters under different driving context conditions. Experimental validation was conducted using the on-the-road car-following behavior of sixty-four drivers. The results showed that under two particular context conditions, drivers demonstrated distinct driving characteristics that could be efficiently recognized by stochastic driver-behavior models, and yet, some context-specific models could be exploited to predict driving behavior in other driving contexts.

Mailis-Gagnon A., Lakha S.F., Furlan A., Nicholson K., Yegneswaran B., Sabatowski R.

The effect of opioids on driving performance has been much debated. Driving is a complex task requiring integration of psychomotor, cognitive, motor and decision-making skills, visual-spatial abilities, divided attention, and behavioral and emotional control. The objective of this systematic review was to assess the quality of studies and to revisit the concept that patients on stable opioids are safe to drive as it applies to everyday practice.We searched MEDLINE, EMBASE, PSYCinfo, CENTRAL, TRANSPORT, CINAHL, reference lists of retrieved articles and narrative reviews, for studies on chronic cancer and noncancer pain patients on opioids, tested by driving, driving simulator, or cognitive/psychomotor tests. Methodological quality was assessed with Methodological Index for Nonrandomized Studies, cognitive/psychomotor tests were appraised regarding their sensitivity and validation, and whether confounding variables potentially affecting the study conclusions were recorded. The results were analyzed both quantitatively and qualitatively.We included 35 studies (2044 patients, 1994 controls), 9% of the studies were of poor, 54% of fair, and 37% of high quality; 3 quarters of the studies used high sensitivity cognitive tests. Amount and dose of opioids varied largely in many studies. Mean number of possible but unreported confounders was 2.2 (range, 0 to 4), relating to failure of the studies to mention co-prescriptions with psychotropic effects, pain severity, sleep disorder or daytime somnolence, and/or significant depressive or anxiety-related problems.The commonly held concept that "chronic pain patients on stable opioids are safe to drive" cannot be generalized to all such patients in everyday practice, but may be applicable only to a subset who meet certain criteria.