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

Head-mounted displays and dynamic text presentation to aid reading in macular disease

The majority of individuals living with significant sight loss have residual vision which can be enhanced using low vision aids. Smart glasses and smartphone-based headsets, both increasing in prevalence, are proposed as a low vision aid platform. Three novel tests for measuring the visibility of displays to partially sighted users are described, along with a questionnaire for assessing subjective preference. Most individuals tested, save those with the weakest vision, were able to see and read from both a smart glasses screen and a smartphone screen mounted in a headset. The scheme for biomimetic scrolling, a text presentation strategy which translates natural eye movement into text movement, is described. It is found to enable the normally sighted to read at a rate five times that of continuous scrolling and is faster than rapid serial visual presentation for individuals with macular disease. With text presentation on the smart glasses optimised to the user, individuals with macular disease read on average 65% faster than when using their habitual optical aid. It is concluded that this aid demonstrates clear benefit over the commonly used devices and is thus recommended for further development towards widespread availability

Simulating Macular Degeneration to Investigate Activities of Daily Living: A Systematic Review

Purpose: Investigating difficulties during activities of daily living is a fundamental first step for the development of vision-related intervention and rehabilitation strategies. One way to do this is through visual impairment simulations. The aim of this review is to synthesize and assess the types of simulation methods that have been used to simulate age-related macular degeneration (AMD) in normally sighted participants, during activities of daily living (e.g., reading, cleaning, and cooking).Methods: We conducted a systematic literature search in five databases and a critical analysis of the advantages and disadvantages of various AMD simulation methods (following PRISMA guidelines). The review focuses on the suitability of each method for investigating activities of daily living, an assessment of clinical validation procedures, and an evaluation of the adaptation periods for participants.Results: Nineteen studies met the criteria for inclusion. Contact lenses, computer manipulations, gaze contingent displays, and simulation glasses were the main forms of AMD simulation identified. The use of validation and adaptation procedures were reported in approximately two-thirds and half of studies, respectively.Conclusions: Synthesis of the methodology demonstrated that the choice of simulation has been, and should continue to be, guided by the nature of the study. While simulations may never completely replicate vision loss experienced during AMD, consistency in simulation methodology is critical for generating realistic behavioral responses under vision impairment simulation and limiting the influence of confounding factors. Researchers could also come to a consensus regarding the length and form of adaptation by exploring what is an adequate amount of time and type of training required to acclimatize participants to vision impairment simulations

Developing a user-centered accessible virtual reality video environment for severe visual disabilities

We address a timely issue of accessibility for visual information through the means of videos. Using emerging technologies (Head Mounted Virtual Reality Displays) and a user-centred design approach, we provide people with severe visual disabilities with a bespoke platform for accessing and viewing videos. We report on newly created test methods for measuring acuity within virtual spaces and reactions of impaired individuals, which informed our platform's design, to inform similar designs and allow testing and refinement for ecological and external validity. A prototype software for accessible virtual reality video viewing is presented, with a subsequent user evaluation to test the software, and a newer virtual reality head mounted display to determine usability while measuring how visually impaired users utilize elements in a virtual environment. We give guidance, based on empirical evidence, and advocate that although VR technologies are currently primarily targeted at a generic audience (gaming and entertainment), they can and should be further developed as assistive tools that enable independent living and increase the quality of life for those with disabilities, and specifically severe visual impairments

Improving face perception and quality of life in age-related macular degeneration

The ability to see faces is essential for successful social interactions and good quality of life. Age-related macular degeneration (AMD) is a progressive eye condition that damages central vision required to see faces clearly. This thesis aims to investigate potential means to improve quality of life in AMD, via a two-pronged approach. The first prong examines the importance of face recognition difficulties, using a qualitative study of the effects of poor face perception in AMD on social interactions and quality of life. Previous studies of the impact of AMD on quality of life have focussed on domains including reading, driving, and self-care. Paper 1 of the thesis presents the first in-depth study of the quality-of-life impacts arising specifically from poor face perception. Results showed that, across all levels of vision loss (still driving through legally blind), AMD patients experience everyday problems with recognising who people are (face identity) and their emotions (facial expressions). These result in difficulties in social interactions, fear of offending others (e.g., appearing to ignore them deliberately), misinterpreting how others are feeling, and missing out in social situations. Patients also reported others did not understand their vision loss, and worried about appearing a fraud. These outcomes often contributed to social withdrawal and reduced confidence and quality of life. Paper 1 uses the study findings to develop new community resources (Faces and Social Life in AMD information sheet, conversation-starter, brochure for low-vision clinics), intended to improve patient and community understanding of how AMD affects face perception, and to provide practical tips for improving social interactions. The second prong focusses on improving face perception in AMD patients via image enhancement. The broad idea here is that, potentially, face images can be displayed to patients on screens or smart glasses after being digitally altered in ways that make them easier for patients to see and interpret. The specific image enhancement tested here is caricaturing, which involved exaggerating the shape information in the face image away from the average face (for face identity) or a neutral expression (for face expression). Paper 2 demonstrates that caricaturing can improve perception of identity in AMD; this benefit was observed for all eyes tested with mild vision loss, and half of eyes tested with moderate-to-severe vision loss. Paper 3 demonstrated that caricaturing can improve perception of facial expression in AMD, particularly for low-intensity expressions that are poorly recognised in their natural form, again across a wide range of vision loss. Overall, this thesis demonstrates that poor face perception in AMD is an important contributor to patients’ reduced quality of life. With the aim of enhancing quality of life, I have developed resources to improve community understanding, plus demonstrated that caricaturing provides a useful image enhancement method in AMD. Future research should focus on: further evaluation of the helpfulness of the community resources (to patients, carers and orthoptists); testing whether combining image enhancement methods (e.g., caricaturing plus contrast manipulations) can further improve face perception; and engineering advances needed to implement accurate caricaturing for patients in real-time

Evaluation of a low vision training programme

In some countries, notably the United States and Sweden, intensive training is considered an important adjunct to low vision services in the rehabilitation of the visually handicapped. Recently, such training has been introduced into the United Kingdom. Central to many of the programmes for reading are the techniques of eccentric viewing (EV) and steady eye strategy (SES). Although the techniques have been available for the last 15 years and their justification is widely accepted, to date they have not been validated by scientific studies. Two studies were designed to test the hypothesis that intensive training improves the near vision performance with an optical magnifier. Patients with a severe central defect due to age-related macular degeneration were recruited to study "A" (N=57), and patients with a less severe defect to study "B" (N=43). One training and two comparison groups were used in each study. During initial training, 43% of patients believed that EV would be helpful for simple tasks. However, eight months later, only 6.3% in study "A" and 10% in study "B" considered that they had used EV regularly and successfully for reading. The SES had been beneficial to 12.5% in "A" and 0% in "B". There was no significant difference in the near vision performance between the group of trained patients and the comparison groups. A depression index, assessed by the General Health Questionnaire, correlated with neither the method of management nor visual performance for patients in study "A". This is the first time that a trial of this type has been undertaken. It shows that standard management is as effective as training in the rehabilitation of patients. Since standard management is less time consuming it is more cost efficient. These conclusions are relevant to a service for which there is a high requirement and low provision in the United Kingdom

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