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Functional biomarkers of hypoxia in age-related macular degeneration

Callaghan, Tamsin 2016. Functional biomarkers of hypoxia in age-related macular degeneration. PhD Thesis, Cardiff University.
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Abstract

Age-related macular degeneration (AMD) is predicted to affect 196 million people by 2020 (Wong et al. 2014). To date there is no clear pathogenesis for the condition however, hypoxia has been implicated (Stefánsson et al. 2011). Currently, treatment is only available for neovascular AMD. To develop treatments targeted for early AMD a better understanding of the pathogenesis is required. There is also a need for sensitive functional biomarkers to improve diagnosis and monitoring and to expedite the evaluation of therauptics in clinical trials. The aim of this research was to investigate the hypothesis that hypoxia is involved in the pathogenesis of early AMD. Studies were carried out exploring the effect of transient systemic hypoxia (14% oxygen) and hyperoxia (60% oxygen) on scotopic thresholds and electroretinograms (ERGs) of participants with early AMD. It was hypothesised that the visual function of participants with AMD, but not age-matched controls, would improve during the hyperoxic episode and that hypoxia would have a greater detrimental effect on visual function in people with early AMD. There were no significant differences in scotopic thresholds within each group when breathing 60% or 14% oxygen compared to medical air (21% oxygen). There were also no significant differences in full-field ERG parameters between gas conditions or groups, apart from the amplitude of the b-wave which was significantly reduced under hypoxia in the control group. The amplitude of the focal flicker ERG was significantly higher in the control group than the AMD group when breathing both 14% and 21% oxygen. However, there were no significant differences in the parameters of the focal ERG within each group. These findings suggest that hypoxia is not responsible for the elevation of scotopic thresholds reported in AMD. There is also no evidence that ERG changes are attributable to hypoxia. This thesis provides no evidence to support the role of hypoxia in the pathogenesis of early AMD.

Item Type: Thesis (PhD)
Status: Unpublished
Schools: Optometry and Vision Sciences
Subjects: R Medicine > RE Ophthalmology
Uncontrolled Keywords: Age-related macular degeneration, Hypoxia, scotopic visual function.
Date of First Compliant Deposit: 5 January 2017
Last Modified: 24 Jan 2018 02:30
URI: http://orca.cf.ac.uk/id/eprint/97168

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