Assessing Visual Function in the Older Driver

Modeling of older adults' driving exposure and avoidance using objective driving data in a naturalistic driving study

Older adults in the United States rely heavily on driving their own vehicles to commute to work, shop for groceries, and access public services. To effectively help older adults maintain mobility and independence,we need to better understand how thecognitive, visual functioning, and health declines influence their tendency to self-restrict their driving. The objective of this study is to develop a causal model to examine the effects of age, gender, household status (specifically living alone), physical, cognitive, visual abilities, and health status on older adults' driving mobility in terms of driving exposure and avoidance. Driving exposure was measured by actual driving data, whereas driving avoidance was assessed by both self-report data and actual driving exposure to challenging situations. Structural equation modeling was used to analyze data collectedin the Second Strategic Highway Research Program Naturalistic Driving Study for establishing relationships between the selected factors and mobility. The structural equation model included a total of794 participants aged 65 and over (367 or 46.22%femalesand 427 or 53.78% males). Results indicate that poorer health is associated with less driving exposure; deteriorating cognitive and physical capabilities are associated with more self-reported driving avoidance and less actual driving in challenging situations; visual function is associated with self-reported avoidance; living alone is associated with higher driving exposure in general as well as in challenging situations; self-reported driving avoidance of challenging situations has a negative association with actual driving in those same situations. The final model could be applied to predict older adults' mobility changes according to their age, gender, household status, as well as their visual, physical, cognitive and health status.

Spatial navigation ability and gaze switching in older drivers: A driving simulator study

Objective

Driving ability in older people is affected by declining motor, cognitive and visual functions. We compared perceptual and cognitive skills and driving behaviour in a Japanese population.

Methods

We used a driving simulator to measure the effects of spatial navigation skills and eye movements on driving ability. Participants were 34 older and 20 young adults who completed a simulated driving task involving a lane change and a right turn at an intersection. We used an eye tracker to measure gaze. We measured visual recognition (Benton Judgment of Line Orientation Test (BJLO)), spatial navigation (Card-Placing Test (CPT A & B)), visual perception (Raven's Colored Progressive Matrices (RCPM)) and driving ability (Stroke Drivers' Screening Assessment).

Results

Older participants scored significantly lower on the BJLO, CPT-A & B and RCPM, showed a significant correlation between gaze time and CPT-A & B scores (both p < .01) and had a longer gaze time. There were significant between-group differences in saccade switching (p < .01 right turn), distance per saccade (p < .05 for right turn and lane change) and saccade total distance (p < .05 right turn; p < .01 lane change). There was an association between age and rate of gaze at the right door mirror (p = 0.04).

Conclusion

The findings indicate that older drivers have poorer eye movement control and spatial navigation. This is likely to result in delayed responses and difficulties in predicting the on-coming driving environment. Driving simulation could help older drivers in their driving abilities.

Effects of a Voice Interface on Mirror Check Decrements in Older and Younger Multitasking Drivers

Older drivers comprise an undue percentage of roadway crashes and fatalities, and existing data implicates decrements to situational awareness as one factor. Although forward attention in older drivers is well studied, rearward attention for this population is little explored. What evidence exists has suggested reduced mirror checks, especially under conditions of multitasking. Voice-enabled in-vehicle systems may represent a partial solution, requiring fewer resources and freeing drivers for behavior which maintains better rearward attention. The present study asked participants to drive on a highway in an instrumented vehicle under conditions of baseline driving, manual radio tuning, and radio tuning assisted by a voice-enabled interface. Results indicate that multitasking greatly reduced mirror checks for all groups. Older participants devoted a greater amount of time to mirror checks than younger participants when just driving, but dropped to levels similar to younger drivers while multitasking. Voice-enabled radio tuning was associated with reduced decrements in mirror checks for all age groups. Discussion centers around this new understanding of differing attentional patterns across lifespan, as well as the impact of voice-enabled interface.

Use of Passenger Vehicles by Older People with Disabilities

The goal of this study was to identify the range of problems faced by frail older people in using private passenger vehicles and to identify how assistive technology and selection of vehicles may reduce those problems. Research activities included a review of existing research, a review of assistive technology for vehicle use, four focus group sessions, and a survey of 101 older people with disabilities. The findings of the research indicated that frail older people had significant problems both as drivers and as passengers. Although they are reluctant to self-report driving problems, they did report many problems entering and exiting vehicles. Forty percent of those surveyed reported difficulty getting their legs in and out. The study identified many ways that occupational therapists can assist frail older people and their caregivers in using passenger vehicles. It also identifies gaps in research, vehicle design, and assistive technology that need to be addressed.

Screening and assessment tools for determining fitness to drive: a review of the literature for the pathways project

With a brief introduction, 10 tables summarize the findings from the literature describing screening and assessment tools used with older adults to identify risk or determine fitness to drive. With a focus on occupational therapy's duty to address driving as a valued activity, this paper offers information about tools used by occupational therapy practitioners across practice settings and specialists in driver rehabilitation. The tables are organized into groups of key research studies of assessment tools, screening batteries, tools used in combination (i.e., as a battery), driving simulation as an assessment tool, and screening/assessment for individuals with stroke, vision impairment, Parkinson's disease, dementia, and aging. Each table has a summary of important concepts to consider as occupational therapists choose the methods and tools to evaluate fitness to drive.

Predictors of Driving Ability Following Stroke: A Systematic Review

BACKGROUND AND PURPOSE

The objective of this review is to identify the most consistent predictors of driving ability post stroke.

METHOD

A computerized search of numerous databases from 1966 forward was completed. Measured outcomes included voluntary driving cessation or results of on-road driving evaluation. Studies were evaluated using the Newcastle-Ottawa Quality Assessment Scale.

RESULTS

17 eligible studies were identified. The most useful screening tests were tests assessing cognitive abilities. These included the Trail Making A and B tests, the Rey-Osterreith Complex Figure Design, and the Useful Field of View Test.

CONCLUSION

Cognitive tests that assess multiple cognitive domains relevant to driving appear to have the best reproducibility in predicting fitness to drive in stroke patients.

Traffic-entry behavior and crash risk for older drivers with impairment of selective attention

Current research suggests that older drivers with declines in selective attention would make more unsafe traffic-entry judgments than would older drivers with normal attention. This hypothesis was tested using an instrumented vehicle and a LIDAR speed and range detector. Participants were 20 older drivers: 10 (M=72.0 yr.) had impairments of selective attention, measured with the Visual Attention Analyzer, Model 3000, and 10 were nonimpaired (M=71.2 yr.). Drivers pressed a button to indicate the last possible moment they could safely cross a road in front of an oncoming vehicle. The speed and distance of the oncoming vehicles were measured and time-to-contact was calculated. Each driver's time-to-cross the roadway was independently measured. Attention-impaired drivers showed shorter time-to-contact values (5.60 sec. versus 6.86 sec.), took longer to cross the roadway (5.41 sec. versus 4.84 sec.), and had shorter safety cushions (the difference between time-to-contact and time-to-cross the roadway). Monte Carlo simulation showed that these performance differences increased the crash risk of the impaired group by up to 17.9 times that of the nonimpaired group.

Effects of planar and non-planar driver-side mirrors on age-related discomfort-glare responses

In this study, we evaluated subjective nighttime discomfort-glare responses on three different types of planar and non-planar driver-side mirrors on two age groups. Fifty-six individuals (28 young [18-35 years] and 28 old [65 years and over]) participated in this experiment. Subjective discomfort-glare rating scores on three different types of driver-side mirrors were assessed utilizing De Boer's rating scale in a controlled nighttime driving environment (laboratory ambient illuminant level-l lux with headlight turned off). Three driver-side mirrors included planar "flat mirror": radius of curvature 242650.92 mm, reflectivity 0.60114, and surface reflectance 0.60568; "curved mirror": radius of curvature 1433.3 mm, reflectivity 0.21652, and surface reflectance 0.58092; "blue mirror": radius of curvature 1957.1 mm, reflectivity 0.25356, and surface reflectance 0.54585. The results indicated that with the same glare level (as measured by angle of incidence and illuminance in front of the eyes), older adults reported worse feelings of glare than their younger counterparts. Furthermore, the results indicated that both young and older adults reported worse feelings of glare for planar driver-side mirror than non-planar driver-side mirrors. These results suggest that older adults' criterion of discomfort-glare is more sensitive than their younger counterparts, and importantly, the non-planar driver-side mirrors can be beneficial in terms of reducing nighttime discomfort-glare for both the young and the elderly.

Vision and falls

Falls occur in about one third of older people living independently in the community every year. This can lead to significant physical, psychological and financial costs to the individual and the community. While the risk factors for falls in older people are multifactorial, poor vision is considered to be an important contributing factor. The aim of this review is to evaluate current research linking impaired visual function with falls and to review current intervention strategies for the prevention of falls in older individuals. The evidence from the current literature indicates that impairment of visual functions, such as visual acuity, contrast sensitivity, visual fields and depth perception, is associated with an increased risk of falls. Recent studies have also demonstrated that falls can be reduced following cataract surgery as a visual intervention. Optometrists need to be aware of these associations and through appropriate treatment, referral and/or education, they can play a major role in optimising visual function in older people, as part of a multidisciplinary approach to falls prevention.

Driving habits and patterns in older men with glaucoma

Glaucoma, an eye disorder that gradually decreases peripheral vision, affects millions of older adults. Consequences of glaucoma can mean changes in the ability to perform familiar tasks, including driving an automobile. We surveyed older drivers with glaucoma and a control comparison group in order to learn more about their driving habits and expectations about driving cessation. Findings indicate that compared to the control group, drivers with glaucoma are significantly more likely to change their driving habits with regard to driving at night (p=0.003), on freeways (p=0.05), and in unfamiliar areas (p=0.01). Drivers with glaucoma were also significantly more likely to report family concern about their driving (p=0.01). However, the drivers with glaucoma did not anticipate that their disease would force them to discontinue driving. Social workers play a pivotal role in coordinating the complex care needs of visually impaired elders. When driving skills are affected, social workers must address transportation, housing as well as quality of life concerns.

Effects of normal aging on the performance of motor-vehicle operational skills

Operational skills involved in controlling a motor vehicle were measured in two groups of very healthy elderly drivers and a young control group to test the hypothesis that there are age-related declines in operational performance that may influence driver safety. An actual behind-the-wheel, standardized road test was employed using a motor vehicle equipped with sensors to record speed, braking activity, and lane position, as well as direction and magnitude of front-wheel and eye-movement excursions. The data from these sensors were used as dependent measures of operational performance. Older drivers made fewer steering and eye-movement excursions and drifted across the center line more frequently than the young control group. Younger drivers drove significantly faster and executed more braking applications than did their older counterparts. The motor-vehicle operational performance of older healthy drivers was related to visual-spatial attentional declines and the useful field of vision associated with the normal aging process.

Age-related functional field losses are not eccentricity dependent

Previous studies have found an increase in peripheral target localization errors in normally sighted older adults. These results have been interpreted as indicative of a constriction of the "useful field of view". In the present study, we parametrically manipulated masking, distractors and stimulus luminance and examined the relationships between peripheral target localization and age. We found that backward masking and/or flashed distractors increased error rates. This decrement in performance was larger for more peripherally located targets and largest for the older subjects at all stimulus locations. Stimulus luminance (either 2 or 78 cd/m2) had no effect on peripheral localization performance at any age. We also demonstrated that all subjects, regardless of age, had higher localization error rates to more peripherally located targets. In older subjects, error rates increased equally at all eccentricities; that is, there was an eccentricity independent increase in the number of target localization errors as a function of age. This finding does not support the interpretation of a selective constriction of the functional visual field in older subjects.

Automobile driving in Huntington's disease

We assessed the influence of the neurological and cognitive impairments of Huntington's disease (HD) on automobile driving. In a group of 73 HD outpatients, 53 (72%) continued to drive after illness onset. Those no longer driving had more severe symptoms than those still driving. Twenty-nine HD patients who were still driving and 16 healthy control subjects underwent a clinical examination, a cognitive examination, a driving-simulator assessment, and completed questionnaires about driving history and habits. HD patients performed significantly worse than control subjects on the driving-simulator tasks and were more likely to have been involved in a collision in the preceding 2 years (58% of HD vs. 11% of control subjects). Patients with collisions were less functionally impaired but had slower simple reaction time scores than did those without collisions. HD patients are at increased risk for accidents, but patients who have accidents are not easily distinguished from those who do not.