ACE-DNV: Automatic classification of gaze events in dynamic natural viewing.

Eye movements offer valuable insights for clinical interventions, diagnostics, and understanding visual perception. The process usually involves recording a participant's eye movements and analyzing them in terms of various gaze events. Manual identification of these events is extremely time-consuming. Although the field has seen the development of automatic event detection and classification methods, these methods have primarily focused on distinguishing events when participants remain stationary. With increasing interest in studying gaze behavior in freely moving participants, such as during daily activities like walking, new methods are required to automatically classify events in data collected under unrestricted conditions. Existing methods often rely on additional information from depth cameras or inertial measurement units (IMUs), which are not typically integrated into mobile eye trackers. To address this challenge, we present a framework for classifying gaze events based solely on eye-movement signals and scene video footage. Our approach, the Automatic Classification of gaze Events in Dynamic and Natural Viewing (ACE-DNV), analyzes eye movements in terms of velocity and direction and leverages visual odometry to capture head and body motion. Additionally, ACE-DNV assesses changes in image content surrounding the point of gaze. We evaluate the performance of ACE-DNV using a publicly available dataset and showcased its ability to discriminate between gaze fixation, gaze pursuit, gaze following, and gaze shifting (saccade) events. ACE-DNV exhibited comparable performance to previous methods, while eliminating the necessity for additional devices such as IMUs and depth cameras. In summary, ACE-DNV simplifies the automatic classification of gaze events in natural and dynamic environments. The source code is accessible at https://github.com/arnejad/ACE-DNV .

The 6-Item Vision-Related Quality of Life and Limitations Questionnaire: Evaluation of Psychometric Properties.

Purpose: We developed the Vision-related Quality of life and Limitations Questionnaire (VQL-6), a screening instrument to signal a need for additional care resulting from reduced vision-related quality of life in patients with chronic ophthalmic diseases. The aim of the present study was to evaluate psychometric properties. Methods: A Dutch population-based sample of 2032 participants (mean age, 55 ± 19 years) completed the VQL-6 and other questionnaires on vision-related quality of life, executive functioning, attention, mental health, and symptom validity. In addition, we recruited a sample of 208 ophthalmic patients (mean age, 72 ± 12 years) and 98 age and gender similar controls (mean age, 69 ± 11 years) who completed the VQL-6 and the National Eye Institute Visual Function Questionnaire-25. We studied the factor structure, internal consistency, convergent and divergent validity, and known-groups validity. Results: For the factor analyses, the population-based sample was split randomly in two subsamples. Exploratory factor analysis on the first subsample suggested a two-factor model (visual limitations and general health and quality of life), which was supported by confirmatory factor analyses on the second subsample, and on the patients. The VQL-6 demonstrated good internal consistency within each factor (0.78-0.89), sufficient convergent (r2= 55%) and divergent validity (r2 = 11%-24%), and good known-groups validity (Cohen's r = 0.57; P < 0.001). Conclusions: The VQL-6 has a robust two-factor structure and seems to be a valid tool to assess vision-related quality of life. Additional validation is needed in patients with chronic ophthalmic diseases. Translational Relevance: Future research is needed to determine if the VQL-6 can be used to identify patients with chronic ophthalmic diseases who are in need of additional care.

Reading Difficulties in Parkinson's Disease: A Stepped Care Model for Neurovisual Rehabilitation.

BACKGROUND: People with Parkinson's disease (PD) frequently experience reading difficulties. Little is known about what functional impairments distinguish people with PD with and without reading difficulties and how these should guide rehabilitation. OBJECTIVE: To provide concrete advice for an efficient stepped care model for reading difficulties in PD, based on extensive functional assessments. METHODS: This study included 74 people with PD in a neurovisual rehabilitation setting who underwent assessment of visual, visuoperceptual, and cognitive functions. Outcomes were compared between those with frequent (RD+; N = 55) and infrequent reading difficulties (RD-; N = 19). Aids and advice provided during rehabilitation were registered. RESULTS: Only a few functions appeared to distinguish RD+ and RD-. Visual functions (i.e., contrast sensitivity, g = 0.76; reading acuity, g = 0.66; visual acuity, g = 0.54) and visuoperceptual functions (i.e., visual attention, g = 0.58, visual motor speed, g = 0.56) showed significant worse scores in RD+ compared to RD-. Aids and advice applied consisted mainly of optimizing refraction, improving lighting, and optimizing text size and spacing. CONCLUSION: The test battery showed significant differences between RD+ and RD-on only a few tests on visual and visuoperceptual functions. The applied aids and advice matched well with these impairments. Therefore, we recommend a stepped care model, starting with a short test battery on these functions. If this battery indicates functional impairments, this can be followed by standard aids and advice to improve reading. Only in case of insufficient effect additional testing should take place.

A systematic review on visual scanning behaviour in hemianopia considering task specificity, performance improvement, spontaneous and training-induced adaptations.

PURPOSE: People with homonymous hemianopia (HH) benefit from applying compensatory scanning behaviour that limits the consequences of HH in a specific task. The aim of the study is to (i) review the current literature on task-specific scanning behaviour that improves performance and (ii) identify differences between this performance-enhancing scanning behaviour and scanning behaviour that is spontaneously adopted or acquired through training. MATERIALS AND METHODS: The databases PsycInfo, Medline, and Web of Science were searched for articles on scanning behaviour in people with HH. RESULTS: The final sample contained 60 articles, reporting on three main tasks, i.e., search (N = 17), reading (N = 16) and mobility (N = 14), and other tasks (N = 18). Five articles reported on two different tasks. Specific scanning behaviour related to task performance in search, reading, and mobility tasks. In search and reading tasks, spontaneous adaptations differed from this performance-enhancing scanning behaviour. Training could induce adaptations in scanning behaviour, enhancing performance in these two tasks. For mobility tasks, limited to no information was found on spontaneous and training-induced adaptations to scanning behaviour. CONCLUSIONS: Performance-enhancing scanning behaviour is mainly task-specific. Spontaneous development of such scanning behaviour is rare. Luckily, current compensatory scanning training programs can induce such scanning behaviour, which confirms that providing scanning training is important.IMPLICATIONS FOR REHABILITATIONScanning behaviour that improves performance in people with homonymous hemianopia (HH) is task-specific.Most people with HH do not spontaneously adopt scanning behaviour that improves performance.Compensatory scanning training can induce performance-enhancing scanning behaviour.

Prevalence and nature of self-reported visual complaints in people with Parkinson's disease-Outcome of the Screening Visual Complaints questionnaire.

INTRODUCTION: Visual complaints can have a vast impact on the quality of life of people with Parkinson's disease (PD). In clinical practice however, visual complaints often remain undetected. A better understanding of visual complaints is necessary to optimize care for people with PD and visual complaints. This study aims at determining the prevalence of visual complaints experienced by a large outpatient cohort of people with PD compared to a control group. In addition, relations between visual complaints and demographic and disease-related variables are investigated. METHODS: The Screening Visual Complaints questionnaire (SVCq) screened for 19 visual complaints in a cohort of people with idiopathic PD (n = 581) and an age-matched control group without PD (n = 583). RESULTS: People with PD experienced significantly more complaints than controls, and a greater impact of visual complaints on their daily lives. Complaints that were most common ('often/always') were unclear vision (21.7%), difficulty reading (21.6%), trouble focusing (17.1%), and blinded by bright light (16.8%). Largest differences with controls were found for double vision, needing more time to see and having trouble with traffic participation due to visual complaints. Age, disease duration, disease severity, and the amount of antiparkinsonian medication related positively to the prevalence and severity of visual complaints. CONCLUSION: Visual complaints are highly prevalent and occur in great variety in people with PD. These complaints progress with the disease and have a large impact on the daily lives of these people. Standardized questioning is advised for timely recognition and treatment of these complaints.

Correction: The Screening Visual Complaints questionnaire (SVCq) in people with Parkinson's disease-Confirmatory factor analysis and advice for its use in clinical practice.

[This corrects the article DOI: 10.1371/journal.pone.0272559.].

The Screening Visual Complaints questionnaire (SVCq) in people with Parkinson's disease-Confirmatory factor analysis and advice for its use in clinical practice.

BACKGROUND: The Screening Visual Complaints questionnaire (SVCq) is a short questionnaire to screen for visual complaints in people with Parkinson's disease (PD). OBJECTIVE: The current study aims to investigate the factor structure of the SVCq to increase the usability of this measure in clinical practice and facilitate the interpretation of visual complaints in people with PD. METHODS: We performed a confirmatory factor analysis using the 19 items of the SVCq of 581 people with PD, investigating the fit of three models previously found in a community sample: a one-factor model including all items, and models where items are distributed across either three or five factors. The clinical value of derived subscales was explored by comparing scores with age-matched controls (N = 583), and by investigating relationships to demographic and disease related characteristics. RESULTS: All three models showed a good fit in people with PD, with the five-factor model outperforming the three-factor and one-factor model. Five factors were distinguished: 'Diminished visual perception-Function related' (5 items), 'Diminished visual perception-Luminance related' (3 items), 'Diminished visual perception-Task related' (3 items), 'Altered visual perception' (6 items), and 'Ocular discomfort' (2 items). On each subscale, people with PD reported more complaints than controls, even when there was no ophthalmological condition present. Furthermore, subscales were sensitive to relevant clinical characteristics, like age, disease duration, severity, and medication use. CONCLUSIONS: The five-factor model showed a good fit in people with PD and has clinical relevance. Each subscale provides a solid basis for individualized visual care.

Confirmatory factor analysis of the Dutch Screening Visual Complaints questionnaire in people with multiple sclerosis.

BACKGROUND: Visual complaints among people with multiple sclerosis (pwMS) are common, but often difficult to recognize. The Screening Visual Complaints questionnaire (SVCq) has been developed to screen for visual complaints in people with a neurodegenerative disease, including multiple sclerosis (MS). A previous study performed a factor analysis in a normal population which revealed an acceptable one-factor model, a three-factor model and a five-factor model within the SVCq. To increase the usability of the SVCq in people with MS, the purpose of the current study was to investigate the fit of the three models in a cohort of pwMS. RESULTS: The confirmatory factor analysis on the SVCq in 493 people with MS showed good fit for all the models. The three-factor model (diminished visual perception, altered visual perception and ocular discomfort) outperformed the one-factor model. The five-factor model outperformed both models, which showed that dividing the first factor (diminished visual perception) into three more factors (function-related, luminance-related and task-related) has merit. CONCLUSIONS: All models may be useful in clinical care for pwMS. The one-factor model may give a quick overview of the presence and severity of visual complaints in general. The individual factors, of either the three- or the five factor models, may contribute to a better recognition of the nature of visual complaints in pwMS and may guide further steps in rehabilitation for pwMS with visual complaints.

Self-Reported Visual Complaints in People with Parkinson's Disease: A Systematic Review.

BACKGROUND: Scientific research increasingly focuses on visual symptoms of people with Parkinson's disease (PD). However, this mostly involves functional measures, whereas self-reported data are equally important for guiding clinical care. OBJECTIVE: This review provides an overview of the nature and prevalence of self-reported visual complaints by people with PD, compared to healthy controls. METHODS: A systematic literature search was performed. Studies from three databases (PubMed, PsycInfo, and Web of Science) were screened for eligibility. Only studies that reported results of visual self-reports in people with idiopathic PD were included. RESULTS: One hundred and thirty-nine eligible articles were analyzed. Visual complaints ranged from function-related complaints (e.g., blurred vision, double vision, increased sensitivity to light or changes in contrast sensitivity) to activity-related complaints (e.g., difficulty reading, reaching, or driving). Visual complaints were more prevalent in people with PD compared to healthy controls. The presence of visual complaints leads to a reduced quality of life (QoL). Increased prevalence and severity of visual complaints in people with PD are related to longer disease duration, higher disease severity, and off-state. CONCLUSION: A large proportion of people with PD have visual complaints, which negatively affect QoL. Complaints are diverse in nature, and specific and active questioning by clinicians is advised to foster timely recognition, acknowledgement, and management of these complaints.

Neuropsychological deficits in Posterior Cortical Atrophy and typical Alzheimer's disease: A meta-analytic review.

AIMS: To identify cognitive tests that best differentiate between Posterior Cortical Atrophy (PCA) and typical Alzheimer's Disease (tAD), as well as PCA and healthy control (HC) participants. METHOD: Medline, PsycInfo and Web of Science were systematically searched using terms related to PCA, tAD, and cognitive testing. Seventeen studies were identified, including 441 PCA, 391 tAD, and 284 HC participants. Standardised effect sizes of mean scores were calculated to measure performance differences on cognitive tests for PCA versus tAD and PCA versus HC groups. Meta-analyses used a random effects model. RESULTS: The most discriminating cognitive tests for PCA and tAD presentations were measures of visuospatial function and verbal memory. Large, significant effect sizes were produced for all measures of visuospatial function, most notably for Rey-Osterrieth Copy (Hedges' g = -2.79), VOSP Fragmented letters (Hedges' g = -1.73), VOSP Dot Counting (Hedges' g = -1.74), and VOSP Cube Analysis (Hedges' g = -1.98). For measures of verbal memory, the RAVLT delay and Digit Span Backwards produced significant medium effects (Hedges' g = .62 and -.56, respectively). CONCLUSION: Establishing a common framework for testing individuals with PCA has important implications for diagnosis and treatment, and forms a practical objective for future research. Findings from this meta-analysis suggest that measures of visuospatial function and verbal memory would form an important part of this framework.

Eye Movement Evaluation in Multiple Sclerosis and Parkinson's Disease Using a Standardized Oculomotor and Neuro-Ophthalmic Disorder Assessment (SONDA).

Evaluating the state of the oculomotor system of a patient is one of the fundamental tests done in neuro-ophthalmology. However, up to date, very few quantitative standardized tests of eye movements' quality exist, limiting this assessment to confrontational tests reliant on subjective interpretation. Furthermore, quantitative tests relying on eye movement properties, such as pursuit gain and saccade dynamics are often insufficient to capture the complexity of the underlying disorders and are often (too) long and tiring. In this study, we present SONDA (Standardized Oculomotor and Neurological Disorder Assessment): this test is based on analyzing eye tracking recorded during a short and intuitive continuous tracking task. We tested patients affected by Multiple Sclerosis (MS) and Parkinson's Disease (PD) and find that: (1) the saccadic dynamics of the main sequence alone are not sufficient to separate patients from healthy controls; (2) the combination of spatio-temporal and statistical properties of saccades and saccadic dynamics enables an identification of oculomotor abnormalities in both MS and PD patients. We conclude that SONDA constitutes a powerful screening tool that allows an in-depth evaluation of (deviant) oculomotor behavior in a few minutes of non-invasive testing.

The development of the Screening of Visual Complaints questionnaire for patients with neurodegenerative disorders: Evaluation of psychometric features in a community sample.

BACKGROUND AND OBJECTIVES: Patients with neurodegenerative disorders often experience impairments in visual function. In research and clinical care, visual problems are primarily understood as objective visual impairments. Subjective complaints, referring to complaints from a patient's perspective, receive less attention, while they are of utmost clinical importance to guide assessment and rehabilitation. A 21-item Screening of Visual Complaints questionnaire (SVC) was developed for the assessment of subjective visual complaints in patients with neurodegenerative disorders. This prospective study aims to evaluate the psychometric properties of the SVC in a large community sample. METHODS: A stratified convenience sample of 1,461 healthy Dutch participants (18-95 years) without severe self-reported neurological, ophthalmological or psychiatric conditions completed the SVC, Cerebral Visual Complaints questionnaire (CVC-q), National Eye Institute Visual Function Questionnaire-25 (NEI-VFQ-25), Behavior Rating Inventory of Executive Function-A (BRIEF-A), Questionnaire for Experiences of Attention Deficits (Fragebogen erlebter Defizite der Aufmerkzamkeit; FEDA), Depression Anxiety Stress Scale-21 (DASS-21) and the Structured Inventory for Malingered Symptomatology (SIMS) online. After two weeks, 66 participants completed the SVC again. We evaluated the factor structure, internal consistency, convergent and divergent validity, and test-retest reliability of the SVC. RESULTS: The sample was split in two subsamples to perform exploratory and confirmatory factor analyses. In the first subsample, the exploratory factor analysis extracted three factors from the SVC: diminished visual perception, altered visual perception and ocular discomfort. The confirmatory factor analysis showed this model to be valid in the second subsample. The SVC showed satisfactory convergent validity (NEI-VFQ-25: r = -0.71; CVC-q: r = 0.84) and divergent validity (SIMS: r = 0.26; BRIEF-A: r = 0.29; FEDA: r = 0.40; DASS-21: r = 0.34) and good internal consistency (Cronbach's alpha = 0.85) and test-retest reliability (ICC = 0.82). CONCLUSIONS: The SVC is a valid and reliable tool for the assessment of subjective visual complaints in a community sample and appears promising for clinical use in patients with neurodegenerative disorders.

Effects of low visual acuity on neuropsychological test scores: A simulation study.

Objective: To systematically examine the effect of low visual acuity (LVA) on a number of commonly used neuropsychological tests.Method: In this study, the influence of LVA on a number of commonly used neuropsychological tests was examined in 238 healthy older adults (aged 50-80) without visual or neurological impairment. LVA was simulated using simulation glasses.Results: It was found that a simulated LVA of ∼0.2 (decimal acuity; Snellen 6/30 or 20/100, LogMAR 0.7) had a negative impact on test performance for the Trail Making Test, Complex Figure of Rey (copy score), and Visual Object and Space Perception battery subtest 3, but not for the Mini Mental State Examination and Balloons test. For some tests, the negative impact of LVA increased with age.Conclusions: These results have important implications for the use of neuropsychological tests in the visually impaired population. More specifically, when administering the Trail Making Test, Complex Figure of Rey (copy score), and Visual Object and Space Perception Battery subtest 3 to older people with LVA, low test scores should be interpreted with great caution. Low test scores on the Mini Mental State Examination and Balloons Test are not likely to be caused by LVA and are more likely to reflect actual cognitive impairment. The results contribute to the validity of neuropsychological assessment of older people with visual impairment, leading to more effective and more patient-based rehabilitation.

The effect of target speed on perception of visual motion direction in a patient with akinetopsia.

Although much research has been devoted to the neural correlates of motion perception, the processing of speed of motion is still a topic of discussion. Apart from patient LM, no in-depth clinical research has been done in the past 20 years on this topic. In the present study, we investigated patient TD, who suffered from the rare disorder akinetopsia due to bilateral lesions of V5 after stroke. By means of a Random-Dot-Kinematogram (RDK) in which speed was varied systematically, it was found that TD was impaired in perceiving the direction of movement at speeds exceeding 9 deg/s. Our study suggests that V5 plays an important role in processing high-speed visual motion and further implies that V5 does not play a crucial role in processing low-speed visual motion. A remarkable finding, which has not been shown before, was that TD always reported the opposite direction of the actual movement at a speed of 24 deg/s. This suggests a form of the continuous wagon wheel illusion, which might have been caused by intact brain areas operating at different sampling rates than area V5.

The neuropsychological rehabilitation of visual agnosia and Balint's syndrome.

Visual agnosia and Balint's syndrome are complex neurological disorders of the higher visual system that can have a remarkable impact on individuals' lives. Rehabilitation of these individuals is important to enable participation in everyday activities despite the impairment. However, the literature about the rehabilitation of these disorders is virtually silent. Therefore, the aim of this systematic review is to give an overview of available literature describing treatment approaches and their effectiveness with regard to these disorders. The search engines Psychinfo, Amed, and Medline were used, resulting in 22 articles meeting the criteria for inclusion. Only articles describing acquired disorders were considered. These articles revealed that there is some information available on the major subtypes of visual agnosia as well as on Balint's syndrome which practising clinicians can consult for guidance. With regard to the type of rehabilitation, compensatory strategies have proven to be beneficial in most of the cases. Restorative training on the other hand has produced mixed results. Concluding, although still scarce, a scientific foundation about the rehabilitation of visual agnosia and Balint's syndrome is evolving. The available approaches give valuable information that can be built upon in the future.

Key factors for the bicycle use of visually impaired people: a Delphi study.

Purpose: This study aims to identify the most important factors that influence the independent bicycle use of visually impaired people in the Netherlands.Materials and methods: Both visually impaired people and professionals participated in a two-round online Delphi study (n = 42). In Round 1 the participants identified the factors which they ranked by relevance in Round 2.Results: The participants prioritised environmental factors related to the traffic situation, the characteristics of the infrastructure, and weather and light conditions (Kendall's W = 0.66). They indicated that the most influencing personal factors are related to personality, traffic experience, and personal background (W = 0.58). Glaucoma was ranked as the most relevant ophthalmic condition (W = 0.74), while glare was regarded as the most important factor with respect to the visual functions (W = 0.78).Conclusions: The factors provided by this study can be used to optimise the independent cycling mobility of visually impaired people. More research is needed to investigate, both, how and to what extent the mentioned factors influence the cycling behaviour.Implications for rehabilitationThe results of this study can be used to set priorities during the rehabilitation and training of visually impaired people who wish to cycle independently.Visually impaired cyclists may compensate for the consequences of their visual impairments by taking alternative routes that suit their individual abilities and limitations.Since gaining and maintaining self-confidence is important for independent cycling with a visual impairment, practitioners such as mobility trainers should not only focus on cycling-related skills and abilities, but also aim to improve the self-confidence of visually impaired people who wish to cycle.

The effects of habituation and adding a rest-frame on experienced simulator sickness in an advanced mobility scooter driving simulator.

The aim of this article is to investigate the effect of a physical rest-frame, habituation and age on simulator sickness in an advanced mobility scooter driving simulator. Twenty-six young and 34 older adults completed a total of 12 drives in an advanced mobility scooter driving simulator over two visits. A 2x2 crossover design was used to measure the effect of a rest frame that was added to the driving simulator on either the first or second visit. The Simulator Sickness Questionnaire was used to measure simulator sickness symptoms. A significant decrease in simulator sickness was observed between the first and the second visit. Older adults reported more severe simulator sickness symptoms compared to younger participants. No effect of rest-frame could be found. Habituation appears to be the most effective method to reduce simulator sickness in an advanced mobility scooter driving simulator. More research is needed to investigate simulator sickness in patient groups. Practitioner summary: Experiencing simulator sickness is a major problem across all types of simulators. The present experiment investigated the effect of a rest-frame, habituation and age on developing simulator sickness symptoms in an advanced mobility scooter driving simulator. Habituation appeared to be the most effective method to reduce simulator sickness.

Mobility scooter driving ability in visually impaired individuals.

PURPOSE: To investigate how well visually impaired individuals can learn to use mobility scooters and which parts of the driving task deserve special attention. MATERIALS AND METHODS: A mobility scooter driving skill test was developed to compare driving skills (e.g. reverse driving, turning) between 48 visually impaired (very low visual acuity = 14, low visual acuity = 10, peripheral field defects = 11, multiple visual impairments = 13) and 37 normal-sighted controls without any prior experience with mobility scooters. Performance on this test was rated on a three-point scale. Furthermore, the number of extra repetitions on the different elements were noted. RESULTS: Results showed that visually impaired participants were able to gain sufficient driving skills to be able to use mobility scooters. Participants with visual field defects combined with low visual acuity showed most problems learning different skills and needed more training. Reverse driving and stopping seemed to be most difficult. CONCLUSIONS: The present findings suggest that visually impaired individuals are able to learn to drive mobility scooters. Mobility scooter allocators should be aware that these individuals might need more training on certain elements of the driving task. Implications for rehabilitation Visual impairments do not necessarily lead to an inability to acquire mobility scooter driving skills. Individuals with peripheral field defects (especially in combination with reduced visual acuity) need more driving ability training compared to normal-sighted people - especially to accomplish reversing. Individual assessment of visually impaired people is recommended, since participants in this study showed a wide variation in ability to learn driving a mobility scooter.

Perception in attention deficit hyperactivity disorder.

A large body of research demonstrated that individuals with attention deficit hyperactivity disorder (ADHD) suffer from various neuropsychological deficits. In contrast, less is known and only divergent evidence exists on perceptual functions of individuals with ADHD. This is problematic as neuropsychological and perceptual functions are closely interrelated and are often difficult to disentangle in behavioral assessments. This study presents the conduct and results of a systematic literature review on perceptual functions in children and adults with ADHD. This review considers studies using psychophysical methods (objective measurements) and self- and informant reports (subjective measurements). Results indicate that individuals with ADHD have altered perceptual functions in various domains as compared to typically developing individuals. Increased perceptual functions in individuals with ADHD were found with regard to olfactory detection thresholds, whereas reduced perceptual functions were evident for aspects of visual and speech perception. Moreover, individuals with ADHD were found to experience discomfort to sensory stimuli at a lower level than typically developing individuals. Alterations of perceptual functions in individuals with ADHD were shown to be moderated by various factors, such as pharmacological treatment, cognitive functions, and symptom severity. We conclude by giving implications for daily life functioning and clinical practice.

Vision-related fitness to drive mobility scooters: A practical driving test.

OBJECTIVE: To investigate practical fitness to drive mobility scooters, comparing visually impaired participants with healthy controls. DESIGN: Between-subjects design. SUBJECTS: Forty-six visually impaired (13 with very low visual acuity, 10 with low visual acuity, 11 with peripheral field defects, 12 with multiple visual impairment) and 35 normal-sighted controls. METHODS: Participants completed a practical mobility scooter test-drive, which was recorded on video. Two independent occupational therapists specialized in orientation and mobility evaluated the videos systematically. RESULTS: Approximately 90% of the visually impaired participants passed the driving test. On average, participants with visual impairments performed worse than normal-sighted controls, but were judged sufficiently safe. In particular, difficulties were observed in participants with peripheral visual field defects and those with a combination of low visual acuity and visual field defects. CONCLUSION: People with visual impairment are, in practice, fit to drive mobility scooters; thus visual impairment on its own should not be viewed as a determinant of safety to drive mobility scooters. However, special attention should be paid to individuals with visual field defects with or without a combined low visual acuity. The use of an individual practical fitness-to-drive test is advised.