1. Summary of programme area and objectives

1.1 A major goal of this area is to develop a theoretical understanding of normal visual functioning that can be extended to explain the disabilities experienced by people with low vision, blindness and other visual processing deficits. Examples include the role of vision in spatial cognition, factors that underlie text legibility and reading performance, and the role of visual attention in impaired vision.

1.2 Another primary research focus in this programme is visual assessment and everyday task performance. The challenge for the clinician is to identify which tasks are problematic for a given patient so that a rehabilitation plan can be developed and implemented. Research on valid and reliable assessment tools that allow clinicians to properly identify and treat problems in performing daily visual tasks is essential to improving clinical care.

1.3 The logical partner of visual assessment is the rehabilitation process. The research challenge here is to develop rehabilitation mechanisms proven to be effective in enhancing quality of life, to determine which approaches are most successful with different types of individuals, and to improve the delivery of these services to those in need. The area of technology and assistive devices is a critically important research area because of its central role in the rehabilitation process. This will include the development of new devices, the application of advanced technologies to visual or sensory substitution aids, and the continuous development and exploitation of new technologies, including communication, information, and computer technology. In addition we will identify the most effective environmental modifications, the ease of their implementation and their acceptability and use by visually impaired persons.

  2. Programme plan

2.1 Epidemiological and Service Issues - long term

2.1.1 Clinical trial research and other intervention evaluations to examine the effectiveness of rehabilitation processes for the visually impaired, especially in terms of which strategies are most (vs. least) effective for various sub-populations of patients.

2.1.2 Conduct epidemiological studies on the prevalence and incidence of vision impairment, visual disability and identification of sub-populations that may be at heightened risk.

2.2 Clinical and Laboratory Issues - long term

2.2.1 Carry out research on the visual mechanisms underlying object recognition, locomotion and mobility, skilled movement, and reading, and on the interaction of vision with sensory, motor, and cognitive systems in these complex behaviours. This research should include an examination of neural plasticity, especially how the central nervous system is reorganised after visual processing is disrupted or drastically impaired, and how this plasticity could be exploited to enhance the use of residual vision or other sensory/cognitive systems in the visually impaired.
2.2.2 Develop effective assistive devices and techniques to maximise residual vision and/or substitute for visual information, in order to facilitate the performance of everyday tasks by the visually impaired.

2.2.3 Develop environmental designs and modifications that facilitate access in the home and workplace, and while travelling in public places, in order to enhance independence among the visually impaired.

2.3 Current Focus of the Research Programme - As part of our joint strategy with the Institute of Ophthalmology, Professor Gary Rubin, holder of the Helen Keller Chair in visual rehabilitation is developing a world class centre for research in vision impairment and visual rehabilitation. Such research is inherently multidisciplinary involving professionals in ophthalmology, optometry, psychophysics, education, epidemiology, neurosciences, geriatrics etc. The programme will build on the strengths of both the Institute and Moorfields and will focus on three areas:

2.3.1 A review of existing strategies for visual rehabilitation and their effectiveness

2.3.2 Investigation of the potential utility of a new generation of optoelectronic aids in enhancing the capacity of the remaining retinal 'islands' by targeting images on them. For example we are evaluating binocular eye movement patterns in patients with central scotomas to determine how they are related to size and location of scotomas in each eye. This will involve the use of a fast, high resolution, binocular eye tracking system.

2.3.3 Evaluation of the ability to improve the function of the remaining retinal areas by selective training strategies. There is strong evidence for substantive plasticity in the adult visual system and the ability to increase the functional capacity of components of it. For example, one project is focusing on the development of new training methods to facilitate the acquisition of a single, optimally located preferred retinal fixation locus.

  3. Future development work in the programme during 2002/3

3.1 Low Vision Psychophysics Laboratory

3.1.1 This laboratory will be devoted to the study of everyday task performance by people with vision impairment. These tasks include reading, face and object recognition, mobility, and potentially driving. For many years there has been research on visual task performance ("human factors") that largely has gone unnoticed in the field of vision rehabilitation. This may be due in part to the narrow definition of tasks, the frequent reliance on subjective preference rather than actual performance, and the failure to apply general principles and models of visual information processing.

3.1.2 The psychophysics laboratory will use computer-controlled graphics systems and eyetracking and fundus imaging equipment to address a wide range of unanswered questions about everyday task performance in the visually impaired.

3.2 Vision Impairment Population Laboratory

3.2.1 The primary objective of the population laboratory is to study the impact of vision impairment in the population. There have been countless surveys of the prevalence of blindness and blinding eye diseases throughout the world. However, most of these surveys have been limited to loss of visual acuity, perhaps with the addition of visual field constriction. Moreover, studies of the impact of vision loss have been restricted to subjective questionnaire data. Our recent work has clearly demonstrated that there are other important dimensions of visual function that cannot be captured by visual acuity or visual field tests, alone. These include the loss of contrast sensitivity, stereovision, and sensitivity to motion. We have also developed methods for objectively measuring the impact of vision loss on the performance of everyday tasks like reading, face recognition, and independent navigation. With advances in vision assessment and performance-based testing we can hope to uncover answers to a range of questions with significant public-health implications.

3.3 Clinical Low Vision Research Laboratory

3.3.1 Moorfields Eye Hospital has one of the largest low-vision rehabilitation services in the world. This extraordinary facility provides a unique opportunity to evaluate and advance the state of the art in low-vision care. Despite the increased emphasis on low-vision rehabilitation since abandonment of the "sight saving" philosophy in the 1960's, remarkably little is known about the efficacy of rehabilitation. There are different philosophies across low-vision services. Some emphasize high tech or multidisciplinary approaches while others promote low tech single-provider methods. There is disagreement about the benefits of directed training procedures as opposed to general practise with low-vision devices. New devices and procedures are introduced without firm evidence to support promotional claims. Our research will focus on these issues.