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Title: The development of viewing strategies in patients with macular disease
Author: Crossland, M. D.
Awarding Body: University of London
Current Institution: University College London (University of London)
Date of Award: 2004
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Background: This thesis describes the results of the first longitudinal study of visual behaviour in patients with newly developed macular disease (MD). The study is of a natural history, case series design. Methods: Twenty patients with age-related macular disease and five with juvenile forms of MD were recruited. All patients had developed scotomas in their second affected eye within the previous two weeks. Patients were assessed five times over the next twelve months. In addition to clinical tests, fixation behaviour was assessed using a scanning laser ophthalmoscope, eye movements were measured using an infra-red eyetracker and reading speed was recorded. Multivariate statistical techniques were applied to determine which factors limit reading speed and which variables lead to a change in reading speed. Results: All 25 patients developed a preferred retinal locus (PRL) within six months. Sixteen patients made an adaptation whereby they were unaware of using the PRL. By the end of the study, fifteen patients (60%) repeatedly made eye movements which displayed the characteristics of non-foveating saccades. Saccade efficiency reached normal levels in eight patients (32%). Over the course of the study, reading speed improved in four patients (16%), deteriorated in 7 patients (28%) and remained constant in the remaining 14 patients. Changes in reading speed were due to changes in fixation stability, non-awareness of using the PRL and developing a strategy of repeatedly using the same number of PRLs. The likelihood of a change in reading speed could not be predicted by disease type, visual acuity or scotoma size. Conclusions: It was not possible to predict which patients' reading speed will change from the measures used in this study. The conclusions of this thesis have implications for the counselling of patients with macular disease and the development of training programs for patients with this common, debilitating condition.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available