Vision
Our sight deteriorates with age. Reading becomes difficult and everyday tasks become more challenging. Poor vision is a major contributor to falls and accidents in the home, and deteriorating sight can lead to social isolation and extreme loneliness. SPARC projects are considering some the fundamental changes which take place as the eye ages, the nature and behaviour of the cells, and how the eye and brain work together to process information. These will provide information which is vital for understanding how the individual navigates, for example, when walking in cluttered spaces and when driving in unusual environments. The findings have significance for SPARC projects on driving and activity.
Age-related signalling capacities of the human lens
Dr Ian Michael Wormstone, University of East Anglia
12 months, £50,083
Poster: The Ageing Human Lens
Keywords: Wound-healing, Growth, Signalling, Stress
Fig. 1: A Diagrammatic representation of a post-surgical capsular bag and PCO development.
Clouding of the lens, commonly known as cataract, renders millions blind throughout the world. Currently the only way to treat cataract is by surgical intervention. A cataract operation involves removal of parts of the lens, namely a small opening at the front, and the tissue bulk known as lens fibres. By carrying out this procedure the cloudy region is removed and a clear passage of light created. The remaining lens tissue is termed a capsular bag. Lens cells survive the rigours of surgery, remain in the capsular bag and grow on to all available surfaces and through matrix wrinkling that gives rise to light scatter and a diminished visual quality (Figure 1). This secondary problem is known as posterior capsule opacification (PCO). Injury to the lens, for example cataract surgery drives the rate of proliferation and growth in an age-dependent manner, such that growth rates, both in the clinic and the laboratory for human capsular bags are greater in the young than the old. Therefore, we will investigate using state of the art equipment, the relationship between age and the expression and activation of signalling molecules, which are proteins likely to regulate PCO development. This data will have the added bonus of providing fundamental information on the ageing process and also relate directly to PCO, which through development of therapies could improve the quality of life of cataract patients, who predominantly are aged.
Age, eye movement and motion perception
Dr Tom Freeman, Cardiff University
12 months, £37,229
Poster: Active Vision
Keywords: Eye Movement, Psychophysics, Visual Motion, Sensitivity
Visual images move principally because we move do. Yet little is known about the relationship between motion perception and activity, especially in older observers who often display difficulty with tasks such as driving. To investigate potential causes we develop techniques that combine traditional motion psychophysics with specific types of self-movement. We concentrate on eye movement, specifically smooth pursuit to steadily moving targets, partly because this activity is ubiquitous - we continually pursuit eye movements to maintain gaze on objects of interest. While this allows helps with the visual analysis of fine detail, it also creates some interesting problems for the visual system to solve. In particular, pursuit introduces whole-field changes to the visual image. To help disentangle image motion from world motion, non-visual (extra-retinal) signals for the motor system that carry information about eye velocity synapse with primary motion-processing centres in the cortex. We aim to understand the interaction between pursuit, extra-retinal signals and motion sensitivity, relating each to standard clinical indices of sensory ageing and visual function. Hopefully the work will raise our understanding of fundamental limits to motion perception in a more everyday context. As such it will provide a much needed balance to a field that overemphasises age-related changes to visual perception during static, passive observation.
The contribution of visuomotor decline to falls in older adults during adaptive locomotion
Dr Mark Hollands, Birmingham University
12 months, £51,472
Poster: Falling During Walking
Executive Summary: Mind where you Walk: Older People's Vision and Stepping
Keywords: Ageing, Locomotion, Falling, Looking
In the United Kingdom, around 30% of adults over the age of 65 living in the community fall each year. Falls are a major cause of disability and the leading cause of mortality due to injury among older people aged over 75. Those older people who survive a fall often suffer ongoing problems such as injury and infection, loss of confidence, loss of mobility leading to social isolation and depression, increased dependency and permanent disability. Most falls in all age groups occur during walking on a level surface and therefore there is a clear need to understand the mechanisms underlying age-related changes in walking performance before this major health issue can be fully addressed. Previous research suggests that one contributing factor to age-related falls during walking is likely to be decline in the ability of older adults' brains to process visual information describing environmental features (e.g. obstacles and safe places to step) and use this information to generate appropriate stepping movements. The study will be the first to examine how the brain's ability to use vision in this way is affected by ageing and factors associated with falls risk. This information will be invaluable in contributing to our understanding of why people are more prone to falling with increasing age and help in the development of both diagnostic techniques to identify older adults at risk of falling and treatment and intervention programmes that promote safe walking.
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