Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.430037
Title: Development of a multi-location motion displacement test for detection of early glaucoma
Author: Verdon-Roe, Gay Mary
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2006
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Abstract:
This thesis describes the development of a multi-location motion displacement test (MDT) for the early detection of glaucoma. The test uses line displacement stimuli, which are orientated with the retinal nerve fibre layer (RNFL) and scaled with ganglion cell density. Psychophysical properties of hyperacuity motion displacement were explored and results applied to optimize the stimulus presentation and test format. Investigations included the following: (i) Optical blur: MDT was found to be robust to peripheral astigmatism. The effect of spherical blur was quantified and the implication for discrimination between glaucoma and normal discussed. (ii) Spatial summation properties: equivalent MDT thresholds were demonstrated for equivalent length of single and multi-line stimuli. Equivalent MDT thresholds were also found for stimuli of equivalent energy ( stimulus area * stimulus luminance - background luminance ), in accordance with Ricco's Law. A linear relationship (slope 0.5) was found between log MDT threshold and log relative stimulus energy. A new law is proposed to apply to MDT summation properties, giving the relationship T = KVE T = MDT threshold K = constant E = stimulus energy . This may be used to predict MDT threshold for different configurations of stimuli. (iii) Shortening of response time was observed as stimulus duration is reduced and explained by altered temporal summation properties. The results were applied to modify the subject response window, with benefit of reduced test duration. (iv) Selection of stimulus number and position was made by study of attention, together with application of the anatomical relationship of the RNFL with the optic nerve head. (v) A staircase strategy was developed. Parameters were selected by analysis of results gained within the PhD and earlier studies. Results were pooled to accomplish an operational test. Preliminary assessment indicates that focal glaucomatous defects detected by standard automated perimetry are replicated by the new MDT.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.430037  DOI: Not available
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