The aim of this study was to determine whether visual impairment and age affected driver performance and safety rated during in-traffic driving conditions.
Participants included 30 younger, 25 middle-aged, and 35 older subjects with normal vision and 47 older subjects with visual impairment. All subjects were legally eligible to drive. Driving performance was assessed during in-traffic conditions by a professional driving instructor and an occupational therapist using specific scoring criteria.
Group allocation significantly affected driving performance as assessed by the driving instructor and occupational therapist (p < 0.05). The driving instructor and occupational therapist scores were highly correlated (r = 0.76). Of the drivers who were scored as being unsafe, all were older and the majority (75%) had visual impairment.
Older drivers with or without visual impairment were rated as being less safe than the younger and middle-aged drivers with normal vision.
[Show abstract][Hide abstract] ABSTRACT: Previous research has shown that cognitive deficits arising from neurological impairment can impact on driving performance. The diverse nature of cognitive, perceptual and behavioural impairments experienced by drivers with neurological impairment and the resulting impact on driving ability has been the subject of extensive research involving the use of psychometric off-road measures, road safety statistics, actual on-road driving assessments and self-report. This research has shown that some drivers can compensate for limitations in their driving skills but this is dependent upon realistic self-appraisal of driving abilities. Few studies have investigated the role of self-awareness of driving abilities on on-road driving performance in persons with neurological impairment. Aims: To investigate the relationship between self-awareness of driving related abilities in neurologically impaired drivers and on-road driving performance. Participants: Retrospective data were collated on 79 participants who were referred for Occupational Therapy driving assessment, comprising 24 with Closed Head Injury (CHI) (mean age 24.67 + 5.57 yrs), 30 with Cerebrovascular Accident (CVA) (mean age 61.00 + 9.08 yrs) and 25 with 'Other' diagnosis (mean age 50.64 + 21.14 yrs). All participants held a current driver's licence or learner's permit Results: Five predictor variables were significantly associated with the on-road driving assessment outcome including three demographic variables:- diagnosis (2(2)= 7.69, p = 0.021), time since injury/illness onset (2(2)= 6.40, p = 0.041), and mileage (2(2)= 5.84, p = 0.05); and two self-awareness variables:- reaction time (2(2)= 8.04, p = 0.018), and impulse control (2(2)= 13.47, p = 0.001). Logistic regression yielded a final best model containing two predictor variables (2(4) = 20.81, p = 0.000), including diagnosis (p = 0.02) and self-awareness of impulse control (p = 0.01). Discussion and Conclusion: Participants who over-estimated their driving abilities were more likely to fail a driving assessment or require driving rehabilitation than participants who under-estimated or accurately predicted their performance and participants with a diagnosis of CVA were more likely to fail or require driving rehabilitation than those with a CHI or 'Other' diagnosis.
[Show abstract][Hide abstract] ABSTRACT: Presbyopia affects individuals from the age of 45 years onwards, resulting in difficulty in accurately focusing on near objects. There are many optical corrections available including spectacles or contact lenses that are designed to enable presbyopes to see clearly at both far and near distances. However, presbyopic vision corrections also disturb aspects of visual function under certain circumstances. The impact of these changes on activities of daily living such as driving are, however, poorly understood. Therefore, the aim of this study was to determine which aspects of driving performance might be affected by wearing different types of presbyopic vision corrections. In order to achieve this aim, three experiments were undertaken. The first experiment involved administration of a questionnaire to compare the subjective driving difficulties experienced when wearing a range of common presbyopic contact lens and spectacle corrections. The questionnaire was developed and piloted, and included a series of items regarding difficulties experienced while driving under day and night-time conditions. Two hundred and fifty five presbyopic patients responded to the questionnaire and were categorised into five groups, including those wearing no vision correction for driving (n = 50), bifocal spectacles (BIF, n = 54), progressive addition lenses spectacles (PAL, n = 50), monovision (MV, n = 53) and multifocal contact lenses (MTF CL, n = 48). Overall, ratings of satisfaction during daytime driving were relatively high for all correction types. However, MV and MTF CL wearers were significantly less satisfied with aspects of their vision during night-time than daytime driving, particularly with regard to disturbances from glare and haloes. Progressive addition lens wearers noticed more distortion of peripheral vision, while BIF wearers reported more difficulties with tasks requiring changes in focus and those who wore no vision correction for driving reported problems with intermediate and near tasks. Overall, the mean level of satisfaction for daytime driving was quite high for all of the groups (over 80%), with the BIF wearers being the least satisfied with their vision for driving. Conversely, at night, MTF CL wearers expressed the least satisfaction. Research into eye and head movements has become increasingly of interest in driving research as it provides a means of understanding how the driver responds to visual stimuli in traffic. Previous studies have found that wearing PAL can affect eye and head movement performance resulting in slower eye movement velocities and longer times to stabilize the gaze for fixation. These changes in eye and head movement patterns may have implications for driving safety, given that the visual tasks for driving include a range of dynamic search tasks. Therefore, the second study was designed to investigate the influence of different presbyopic corrections on driving-related eye and head movements under standardized laboratory-based conditions. Twenty presbyopes (mean age: 56.1 ± 5.7 years) who had no experience of wearing presbyopic vision corrections, apart from single vision reading spectacles, were recruited. Each participant wore five different types of vision correction: single vision distance lenses (SV), PAL, BIF, MV and MTF CL. For each visual condition, participants were required to view videotape recordings of traffic scenes, track a reference vehicle and identify a series of peripherally presented targets while their eye and head movements were recorded using the faceLAB® eye and head tracking system. Digital numerical display panels were also included as near visual stimuli (simulating the visual displays of a vehicle speedometer and radio). The results demonstrated that the path length of eye movements while viewing and responding to driving-related traffic scenes was significantly longer when wearing BIF and PAL than MV and MTF CL. The path length of head movements was greater with SV, BIF and PAL than MV and MTF CL. Target recognition was less accurate when the near stimulus was located at eccentricities inferiorly and to the left, rather than directly below the primary position of gaze, regardless of vision correction type. The third experiment aimed to investigate the real world driving performance of presbyopes while wearing different vision corrections measured on a closed-road circuit at night-time. Eye movements were recorded using the ASL Mobile Eye, eye tracking system (as the faceLAB® system proved to be impractical for use outside of the laboratory). Eleven participants (mean age: 57.25 ± 5.78 years) were fitted with four types of prescribed vision corrections (SV, PAL, MV and MTF CL). The measures of driving performance on the closed-road circuit included distance to sign recognition, near target recognition, peripheral light-emitting-diode (LED) recognition, low contrast road hazards recognition and avoidance, recognition of all the road signs, time to complete the course, and driving behaviours such as braking, accelerating, and cornering. The results demonstrated that driving performance at night was most affected by MTF CL compared to PAL, resulting in shorter distances to read signs, slower driving speeds, and longer times spent fixating road signs. Monovision resulted in worse performance in the task of distance to read a signs compared to SV and PAL. The SV condition resulted in significantly more errors made in interpreting information from in-vehicle devices, despite spending longer time fixating on these devices. Progressive addition lenses were ranked as the most preferred vision correction, while MTF CL were the least preferred vision correction for night-time driving. This thesis addressed the research question of how presbyopic vision corrections affect driving performance and the results of the three experiments demonstrated that the different types of presbyopic vision corrections (e.g. BIF, PAL, MV and MTF CL) can affect driving performance in different ways. Distance-related driving tasks showed reduced performance with MV and MTF CL, while tasks which involved viewing in-vehicle devices were significantly hampered by wearing SV corrections. Wearing spectacles such as SV, BIF and PAL induced greater eye and head movements in the simulated driving condition, however this did not directly translate to impaired performance on the closed- road circuit tasks. These findings are important for understanding the influence of presbyopic vision corrections on vision under real world driving conditions. They will also assist the eye care practitioner to understand and convey to patients the potential driving difficulties associated with wearing certain types of presbyopic vision corrections and accordingly to support them in the process of matching patients to optical corrections which meet their visual needs.
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