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Title: Aspects of visual disability in glaucoma
Author: Glen, Fiona Charlotte
ISNI:       0000 0004 2751 0975
Awarding Body: City University London
Current Institution: City, University of London
Date of Award: 2012
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Glaucoma is a chronic and progressive disease of the optic nerve that can lead to irreversible loss of function in the visual field (VF). Whilst much research tends to focus on areas such as the development of measures for diagnosing, monitoring and treating glaucoma, less is known about how this visual degradation manifests itself as the person goes about their lives outside of the clinic. This thesis describes five studies which examine different aspects relating to the experience of disability and the quality of life (QoL) of people with glaucoma. In study I, a systematic literature review revealed that only approximately I % of research studies in glaucoma relate to investigations of the effects of the disease on the patient's QoL, and the proportion of studies relating to QoL in glaucoma was less than in many other disabling chronic diseases, including age related macular degeneration (AMD). More than 80% of the studies identified were found to involve the use of questionnaires; a method that although useful for gaining insight into the patient's own perceptions of their condition, is subject to bias. More objective performance-based measurements of functioning may also be useful for determining the impact of glaucoma on the person's life. This approach was taken in study 2, which investigated the performance of 54 patients with varying levels of glaucomatous VF loss on a face recognition (FR) task compared with 41 people with normal vision. It was found that patients with more advanced VF defects performed significantly worse on average than patients with early and moderate defects, and controls (F=3.2; p<0.05). Multiple regression analysis revealed that contrast sensitivity (CS) measurements were important for FR. The importance of contrast for performance on the FR task was thus investigated further in study 3, which examined the effects of image contrast manipulations on the performance of 40 visually healthy participants on a modified version of the FR task. There were no statistically significant effects across contrast conditions, suggesting difficulties relating to face image contrast alone might not fully explain poorer performance. Study 4 investigated whether eye movements may underlie the likelihood of a patient experiencing task difficulties. It was found that, for patients with significant 10° VF defects, those who made larger eye movements also appeared to be better performers (rho=0.60; p=O.OOI). These effects were not found in people with healthy vision, which could imply that some patients use eye movements to 'adapt' to their condition. A final exploratory study aimed to examine patient perceptions of their VF defect, by interviewing patients about their condition. Patients appeared to differ in terms of their level of awareness of their defect, despite all having advanced VF loss. These findings may suggest the potential of further research investigating the link between conscious awareness of one's defect and the employment of adaptive strategies in glaucoma for overcoming VF loss.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available