Farahbakhsh, Mahtab;
(2021)
Mechanisms of development and plasticity in normal eyesight and heritable eye disease.
Doctoral thesis (Ph.D), UCL (University College London).
Abstract
Mammalian visuospatial function is poor at birth but improves rapidly over the first years of life. Previous research has shown that visual impairments are more responsive to treatments early in life when the visual system is still developing. However, due to lack of accurate and reliable measures of visuospatial function in childhood, understanding of the scope for visual plasticity in development is still poor. This limits evaluation of beneficial effects of novel treatments, such as ocular gene therapy, in children. To address this gap, this PhD project built on recent advances in psychophysics, statistics, fMRI, and child-friendly technologies to design: (1) new measures of monitoring visual development from childhood to adulthood, (2) apply these tests to children with normal vision and those born without functioning cones, and (3) measure the outcome of one of the first gene therapy trials in children. To tackle problems imposed by children’s short attention span, this PhD project used recent statistical procedures (i.e., QUEST+, Watson, 2017), to design novel spatial vision tests that measure the contrast sensitivity function (CSF) of children accurately, reliably, and quickly. This work revealed that visuospatial development of the CSF is marginal after the age of 4 years and is likely mainly explained by non-visual factors. In patients with achromatopsia, the CSF was, unsurprisingly reduced, with high test-retest repeatability. To characterise spatial tuning of the visual cortex mediated by different photoreceptors, a novel child-friendly procedure was designed. fMRI was used to estimate the characteristic of neuronal population receptive fields (pRFs) in the developing visual cortex (Dumoulin & Wandell, 2008), while the silent substitution method (Estevez, 1982; Spitschan, 2018) was used to selectively stimulate cone and rod photoreceptors. These methods were then used to test for reorganisation of spatial tuning in the cortex of achromatopsia patients, and the emergence of cone function after gene therapy.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Mechanisms of development and plasticity in normal eyesight and heritable eye disease |
| Event: | UCL (University College London) |
| Language: | English |
| Additional information: | Copyright © The Author 2021. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences > Institute of Ophthalmology |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10135582 |
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