Magnetic resonance imaging of the visual pathway in glaucoma

Glaucoma, a leading cause of irreversible blindness, is characterized by progressive degeneration of the retinal ganglion cells. The disease is often associated with elevated intraocular pressure which exerts a compressive force on the blood vessels in the eye. For most glaucoma patients, the optic discs are abnormal accompanied by a progressive visual field loss. Once the visual field loss occurs, it is impossible to reverse as the retinal ganglion cells have already died. Lowering intraocular pressure is the only effective treatment in clinic but glaucoma patients with controlled intraocular pressure (<21 mmHg) still have a chance of disease progression. As such, there are likely other factors that contribute to the disease progression. Understanding the complexity of glaucoma pathology could provide new insights on finding new biomarkers for early diagnosis to preserve more vision and developing more effective treatment to stop disease progression.;The overall objective of this dissertation is to develop and optimize a comprehensive multimodality magnetic resonance imaging protocol (anatomy, diffusion and retinotopic functional magnetic resonance imaging) for testing the central hypothesis that magnetic resonance imaging could be a sensitive tool to neuro-degeneration along the visual pathway in glaucoma. Firstly, we used a surface based method to detect the cortical gray matter changes in glaucoma. Then, a novel analysis method of diffusion tensor imaging was implemented to assess the abnormality of individual optic tract and optic radiation diffusivity profiles in glaucoma patients. Finally, wide-view functional magnetic resonance imaging with retinotopic analysis was applied to study the central and peripheral visual functions on glaucomatous visual cortex. For each magnetic resonance imaging method, clinical measurements (visual function, retinal nerve fiber thickness) were compared with magnetic resonance imaging parameters to test the link between visual field loss and brain abnormality.