Ability of head-mounted display technology to improve mobility in people with low vision: a systematic review

Purpose: The purpose of this study was to undertake a systematic literature review on how vision enhancements, implemented using head-mounted displays (HMDs), can improve mobility, orientation, and associated aspects of visual function in people with low vision. Methods: The databases Medline, Chinl, Scopus, and Web of Science were searched for potentially relevant studies. Publications from all years until November 2018 were identified based on predefined inclusion and exclusion criteria. The data were tabulated and synthesized to produce a systematic review. Results: The search identified 28 relevant papers describing the performance of vision enhancement techniques on mobility and associated visual tasks. Simplifying visual scenes improved obstacle detection and object recognition but decreased walking speed. Minification techniques increased the size of the visual field by 3 to 5 times and improved visual search performance. However, the impact of minification on mobility has not been studied extensively. Clinical trials with commercially available devices recorded poor results relative to conventional aids. Conclusions: The effects of current vision enhancements using HMDs are mixed. They appear to reduce mobility efficiency but improved obstacle detection and object recognition. The review highlights the lack of controlled studies with robust study designs. To support the evidence base, well-designed trials with larger sample sizes that represent different types of impairments and real-life scenarios are required. Future work should focus on identifying the needs of people with different types of vision impairment and providing targeted enhancements. Translational Relevance: This literature review examines the evidence regarding the ability of HMD technology to improve mobility in people with sight loss

Visual Impairment and Blindness

Blindness and vision impairment affect at least 2.2 billion people worldwide with most individuals having a preventable vision impairment. The majority of people with vision impairment are older than 50 years, however, vision loss can affect people of all ages. Reduced eyesight can have major and long-lasting effects on all aspects of life, including daily personal activities, interacting with the community, school and work opportunities, and the ability to access public services. This book provides an overview of the effects of blindness and visual impairment in the context of the most common causes of blindness in older adults as well as children, including retinal disorders, cataracts, glaucoma, and macular or corneal degeneration

The Efficacy of Visuomotor Compensatory Training for Individuals with Visual Field Defects

Several approaches have been developed to help patients with partial visual field defects to cope with their visual loss, and the most effective are those that encourage the person to move their eyes more efficiently. This thesis sought to examine the efficacy of a multiplatform compensatory training called Durham Reading and Exploration (DREX) in the rehabilitation of these individuals. Overall, the thesis focuses on two primary aims which include establishing whether the DREX training app completed on either a computer or a touchscreen tablet can be an effective treatment for homonymous visual field defects (HVFDs) caused by brain injury, as well as validating the assessment tasks that have been incorporated into the app. The results from Studies 1 to 3 show that DREX training is clinically effective for HVFD rehabilitation, and the training effect in patients trained using a touchscreen tablet is equivalent to patients trained with a computer, with a meaningful improvement in the quality of life which remains stable over a period of three months. In Studies 4 to 6, the built-in assessments tasks are found to be reliable and valid and can be used confidently to monitor the training progression and outcomes. Study 7 explores the novel observation that DREX training is also beneficial for patients with other types of partial visual field defects like tunnel vision and central visual field loss, demonstrating that this training could potentially be offered to a wider low vision population. Finally, studies 8 and 9 explore whether the blurring of vision, a common comorbid visual impairment in patients with visual field defect, could affect the visual exploration performance and the outcomes of visual exploration training. From these results it is clear that blurring of vision did reduce the search efficacy, but searching behaviour can still be improved with the training. Taken together, the findings from this suite of studies indicate that DREX is an effective and inexpensive treatment for visual field defects in a variety of etiologies, however the comorbid impairments that could affect the rehabilitation should be identified to maximise efficacy of this treatment

Change blindness: eradication of gestalt strategies

Arrays of eight, texture-defined rectangles were used as stimuli in a one-shot change blindness (CB) task where there was a 50% chance that one rectangle would change orientation between two successive presentations separated by an interval. CB was eliminated by cueing the target rectangle in the first stimulus, reduced by cueing in the interval and unaffected by cueing in the second presentation. This supports the idea that a representation was formed that persisted through the interval before being 'overwritten' by the second presentation (Landman et al, 2003 Vision Research 43149–164]. Another possibility is that participants used some kind of grouping or Gestalt strategy. To test this we changed the spatial position of the rectangles in the second presentation by shifting them along imaginary spokes (by ±1 degree) emanating from the central fixation point. There was no significant difference seen in performance between this and the standard task [F(1,4)=2.565, p=0.185]. This may suggest two things: (i) Gestalt grouping is not used as a strategy in these tasks, and (ii) it gives further weight to the argument that objects may be stored and retrieved from a pre-attentional store during this task

The Visual Impairment/Cognitive Impairment Co-morbidity : Examining the Genotype-Structure-Function Relationship

This research was supported by the Canadian National Institute for the Blind Ross C. Purse Doctoral Fellowship (2013), Fonds de Recherche en Sante du Quebec (FRSQ) Doctoral Fellowship, the School of Optometry at the University of Montreal and the Recruitment to Vision Science bursary from the Vision Health Research Network of the FRSQ.Un nombre de recherches rapportent une forte cooccurrence de la dégénérescence maculaire liée à l'âge (DMLA) et la maladie d'Alzheimer (AD), ce qui suggère que les déficiences visuelles et cognitives peuvent être liées. Ceci est davantage soutenu par des similitudes structurelles dans la rétine et le cerveau qui sont des facteurs de risque de maladie partagés et des preuves histopathologiques, y compris le bêta-amyloïde. En raison de cela, l'hypothèse selon laquelle DMLA et AD peuvent également partager des facteurs de risque génétiques. L'objectif de cette recherche était de reproduire des études démontrant une incidence plus élevée d'altération cognitive chez les personnes atteintes de DMLA et d'explorer la relation entre le génotype, la structure, et la fonction dans cette comorbidité. Les résultats ont montré qu'un plus grand nombre de personnes atteintes de DMLA ont obtenu un résultat positif pour déficience cognitive par rapport aux témoins. Le résultat MoCA moyen pour le groupe DMLA était inférieur à celui du groupe témoin, mais ce n'était pas significatif. Ces résultats positifs pour déficience cognitive dans la DMLA et les groupes témoins diffèrent considérablement sur les domaines cognitifs avec lesquels ils avaient des difficultés. Bien que les contrôles aient des difficultés avec la mémoire seulement, ceux avec DMLA ont eu de la difficulté avec la mémoire en plus d'autres domaines cognitifs, ce qui indique un risque plus élevé de progression vers AD. Les résultats génétiques ont montré que les polymorphismes de nucléotide unique (SNP), CFHY402H et ARMS2A69S de DMLA les plus fréquents se produisent dans les fréquences attendues au sein de la population québécoise. FADS1 rs174547, qui a une contribution moins significative à AMD, a été constaté surreprésenter dans la population québécoise, ce qui indique un effet fondateur pour ce SNP. En terme de fonction visuelle, les transporteurs de CFHY402H se sont révélés avoir une mauvaise stabilité de la fixation par rapport aux non-porteurs, tandis que les porteurs d'ARMSA69S avaient une acuité visuelle et une sensibilité au contraste plus médiocres. L'analyse de la structure rétinienne a révélé que CFHY402H était liée à l'augmentation de la zone de Drusen, à la réflexivité moyenne et à l'atrophie géographique, tandis que l'ARMS2A69S avait moins de corrélations avec les caractéristiques du Drusen. Ensemble, ces résultats suggèrent que le SNP de CFH joue un rôle dans la perturbation de l'architecture de la rétine alors que le SNP ARMS2 est impliqué dans le dysfonctionnement des photorécepteurs. Ceci est encore mis en évidence par les résultats des mesures psychophysiques, où les porteurs d'ARMS2A69S avaient une difficulté particulière avec les stimuli de premier ordre qui dépendent fortement de la sensibilité au contraste. Bien qu'aucune différence significative n'a été trouvée dans la performance cognitive basée sur le statut de transporteur CFH ou ARMS2, tous ceux qui ont obtenu une évaluation positive pour une déficience cognitive étaient des porteurs du SNP FADS1 avec des homozygotes ayant les scores cognitifs les plus bas. Ces résultats ont des répercussions sur les domaines de la génétique, de la biologie et de la rééducation à faible vision. En explorant la comorbidité cognitive de DMLA dans l'ensemble du spectre de la fonction génotype-structure, la communication à travers les sciences augmente pour mieux servir la population croissante confrontée à cette comorbidité.Research reports a high co-occurrence of Age-related Macular Degeneration (AMD) and Alzheimer’s Disease (AD), suggesting that visual and cognitive impairments may be related. This is further supported by structural similarities in the retina and brain, shared disease risk factors, and histopathological evidence, including beta-amyloid. Due to this, it is hypothesized that AMD and AD may share genetic risk factors as well. The goal of this research was to replicate studies demonstrating a higher incidence of cognitive impairment among individuals with AMD, and to explore the relationship among genotype, structure, and function in this co-morbidity. The results showed a greater number of individuals with AMD scored positive for mild cognitive impairment (MCI) compared to controls. Mean Montreal Cognitive Assessment score for the AMD group was lower than that of the control group, however this was not significant. Those scoring positive for MCI in the AMD and control groups did differ significantly on the cognitive domains with which they had difficulty. While controls had difficulty with only memory, those with AMD had difficulty with memory in addition to other cognitive domains, indicating a higher risk of progression to AD. The genetic results showed that the most common AMD single nucleotide polymorphisms (SNPs), CFHY402H and ARMS2A69S, occur in the expected frequencies within the Quebec population. FADS1 rs174547, which has a less significant contribution to AMD, was found to be overrepresented in the Quebec population, indicating a possible Founder Effect for this SNP. In terms of visual function, carriers of CFHY402H were found to have greater ecentricity compared to non-carriers while carriers of ARMSA69S had poorer visual acuity and contrast sensitivity. Analysis of retinal structure revealed CFHY402H was related to increased drusen area, mid reflectivity, and geographic atrophy, meanwhile ARMS2A69S had fewer correlations with characteristics of drusen. Taken together, these results suggest that the CFH SNP plays a role in the disruption of retinal architecture while the ARMS2 SNP is involved in photoreceptor dysfunction. This is further evidenced by the results of psychophysical measures, where carriers of ARMS2A69S had particular difficulty with first order stimuli which relies heavily on contrast sensitivity. Although no significant differences were found in cognitive performance based on CFH or ARMS2 carrier status, all those scoring positive for MCI were carriers of the FADS1 SNP with homozygotes having the lowest cognitive scores. These results have implications for the fields of genetics, biology, and low vision rehabilitation. Exploration of the AMD/cognitive impairment co-morbidity across the spectrum of genotype-structure-function increases communication across the sciences to better serve the growing proportion of the population facing this co-morbidity

Keeping track of emotions:audiovisual integration for emotion recognition and compensation for sensory degradations captured by perceptual strategies

The majority of emotional expressions are multimodal and dynamic in nature. Emotion recognition, therefore, requires integration of these multimodal signals. Sensory impairments likely affect emotion recognition, but although sensory impairments are common in older adults, it is unknown how they affect emotion recognition. As more people reach old age, accompanied by an increase in the prevalence of sensory impairments, it is urgent to comprehensively understand audiovisual integration, especially in older individuals. My thesis sought to create a basic understanding of audiovisual integration for emotion recognition and study how audiovisual interactions change with simulated sensory impairments. A secondary aim was to understand how age affects these outcomes. To systematically address these aims, I examined how well observers recognize emotions, presented via videos, and how emotion recognition accuracy and perceptual strategies, assessed via eye-tracking, vary under changing availability and reliability of the visual and auditory information. The research presented in my thesis shows that audiovisual integration and compensation abilities remain intact with age, despite a general decline in recognition accuracy. Compensation for degraded audio is possible by relying more on visual signals, but not vice versa. Older observers adapt their perceptual strategies in a different, perhaps less efficient, manner than younger observers. Importantly, I demonstrate that it is crucial to use additional measurements besides recognition accuracy in order to understand audiovisual integration mechanisms. Measurements such as eye-tracking allow examining whether the reliance on visual and auditory signals alters with age and (simulated) sensory impairments, even when lacking a change in accuracy

Eye movements during visual search in patients with glaucoma

Background: Glaucoma has been shown to lead to disability in many daily tasks including visual search. This study aims to determine whether the saccadic eye movements of people with glaucoma differ from those of people with normal vision, and to investigate the association between eye movements and impaired visual search. Methods: Forty patients (mean age: 67 [SD: 9] years) with a range of glaucomatous visual field (VF) defects in both eyes (mean best eye mean deviation [MD]: –5.9 (SD: 5.4) dB) and 40 age-related people with normal vision (mean age: 66 [SD: 10] years) were timed as they searched for a series of target objects in computer displayed photographs of real world scenes. Eye movements were simultaneously recorded using an eye tracker. Average number of saccades per second, average saccade amplitude and average search duration across trials were recorded. These response variables were compared with measurements of VF and contrast sensitivity. Results: The average rate of saccades made by the patient group was significantly smaller than the number made by controls during the visual search task (P = 0.02; mean reduction of 5.6% (95% CI: 0.1 to 10.4%). There was no difference in average saccade amplitude between the patients and the controls (P = 0.09). Average number of saccades was weakly correlated with aspects of visual function, with patients with worse contrast sensitivity (PR logCS; Spearman’s rho: 0.42; P = 0.006) and more severe VF defects (best eye MD; Spearman’s rho: 0.34; P = 0.037) tending to make less eye movements during the task. Average detection time in the search task was associated with the average rate of saccades in the patient group (Spearman’s rho = −0.65; P < 0.001) but this was not apparent in the controls. Conclusions: The average rate of saccades made during visual search by this group of patients was fewer than those made by people with normal vision of a similar average age. There was wide variability in saccade rate in the patients but there was an association between an increase in this measure and better performance in the search task. Assessment of eye movements in individuals with glaucoma might provide insight into the functional deficits of the disease

Automating the eye examination using optical coherence tomography

Optical coherence tomography (OCT) devices are becoming ubiquitous in eye clinics worldwide to aid the diagnosis and monitoring of eye disease. Much of this uptake relates to the ability to non-invasively capture micron-resolution images, enabling objective and quantitative data to be obtained from ocular structures. Although safe and reasonably quick to perform, the costs involved with operating OCT devices are not trivial, and the requirement for OCT and other imaging in addition to other clinical measures is placing increasing demand on ophthalmology clinics, contributing to fragmented patient pathways and often extended waiting times. In this thesis, a novel “binocular optical coherence tomography” system that seeks to overcome some of the limitations of current commercial OCT systems, is clinically evaluated. This device incorporates many aspects of the eye examination into a single patient-operated instrument, and aims to improve the efficiency and quality of eye care while reducing the overall labour and equipment costs. A progressive framework of testing is followed that includes human factors and usability testing, followed by early stage diagnostic studies to assess the agreement, repeatability, and reproducibility of individual diagnostic features. Health economics analysis of the retinal therapy clinic is used to model cost effectiveness of current practice and with binocular OCT implementation. The binocular OCT and development of other low-cost OCT systems may improve accessibility, however there remains a relative shortage of experts to interpret the images. Artificial intelligence (AI) is likely to play a role in rapid and automated image classification. This thesis explores the application of AI within retinal therapy clinics to predict the onset of exudative age-related macular degeneration in fellow eyes of patients undergoing treatment in their first eye. Together with automated and simultaneous imaging of both eyes with binocular OCT and the potential for low-cost patient-facing systems, AI is likely to have a role in personalising management plans, especially in a future where preventive treatments are available

Smart Assistive Technology for People with Visual Field Loss

Visual field loss results in the lack of ability to clearly see objects in the surrounding environment, which affects the ability to determine potential hazards. In visual field loss, parts of the visual field are impaired to varying degrees, while other parts may remain healthy. This defect can be debilitating, making daily life activities very stressful. Unlike blind people, people with visual field loss retain some functional vision. It would be beneficial to intelligently augment this vision by adding computer-generated information to increase the users' awareness of possible hazards by providing early notifications. This thesis introduces a smart hazard attention system to help visual field impaired people with their navigation using smart glasses and a real-time hazard classification system. This takes the form of a novel, customised, machine learning-based hazard classification system that can be integrated into wearable assistive technology such as smart glasses. The proposed solution provides early notifications based on (1) the visual status of the user and (2) the motion status of the detected object. The presented technology can detect multiple objects at the same time and classify them into different hazard types. The system design in this work consists of four modules: (1) a deep learning-based object detector to recognise static and moving objects in real-time, (2) a Kalman Filter-based multi-object tracker to track the detected objects over time to determine their motion model, (3) a Neural Network-based classifier to determine the level of danger for each hazard using its motion features extracted while the object is in the user's field of vision, and (4) a feedback generation module to translate the hazard level into a smart notification to increase user's cognitive perception using the healthy vision within the visual field. For qualitative system testing, normal and personalised defected vision models were implemented. The personalised defected vision model was created to synthesise the visual function for the people with visual field defects. Actual central and full-field test results were used to create a personalised model that is used in the feedback generation stage of this system, where the visual notifications are displayed in the user's healthy visual area. The proposed solution will enhance the quality of life for people suffering from visual field loss conditions. This non-intrusive, wearable hazard detection technology can provide obstacle avoidance solution, and prevent falls and collisions early with minimal information