An investigation of structure and function in myopia using non-invasive methods

Abstract

The axial elongation of the myopic eye can markedly increase the risk of sight-threatening conditions, the socioeconomic impact of which is projected to increase alongside myopia prevalence. Considering this, much attention has been attributed to identifying therapies to prevent myopia development, with the selection of appropriate biomarkers of progressive myopia being central to such work. The overarching aim of this thesis was to examine changes in the structure and function in the myopic visual system with a view to identifying more appropriate indicators of myopic progression. Specifically, we investigated the relationship of altered ocular biometry and retinal ganglion cell (RGC) density in myopia to the core visual functions of spatial and temporal summation, cortical population receptive field (pRF) characteristics and electroretinogram (ERG) measures. We found that the upper limit of complete spatial summation (Ricco’s Area) was significantly enlarged in myopia, but that this was not accompanied by alterations in temporal summation. The changes in spatial summation appear to be related to alterations in RGC density and concurrent enlargements in cortical pRF size. Whilst there were no differences in full-field ERG amplitudes between myopes and controls when measured using a hand-held instrument and skin electrodes, dark adapted implicit times were significantly delayed in those with longer axial lengths. The work within this thesis indicates that functional correlates of myopic globe expansion may be observed at both the retina and higher visual centres. Further research is required to determine whether the functional changes observed are present prior to myopia development and whether they alter alongside structural parameters in progressive myopia. If so, they could potentially act as non-invasive functional biomarkers to predict myopia onset and detect progression.

Thesis is embargoed until 31st May 2023

Date of Award	May 2021
Original language	English
Sponsors	Department for the Economy
Supervisor	Padraig Mulholland (Supervisor), Kathryn Saunders (Supervisor) & Roger Anderson (Supervisor)