Age-related macular degeneration affects the optic radiation white matter projecting to locations of retinal damage

ABSTRACT PurposeWe investigated the impact of age-related macular degeneration (AMD) on visual acuity and the visual white matter. MethodsWe combined an adaptive cortical atlas and diffusion-weighted magnetic resonance imaging (dMRI) and tractography to separate optic radiation (OR) projections to different retinal eccentricities in human primary visual cortex. We exploited the known anatomical organization of the OR and clinically relevant data to segment the OR into three primary components projecting to fovea, mid- and far-periphery. We measured white matter tissue properties – (fractional anisotropy, linearity, planarity, sphericity) along the aforementioned three components of the optic radiation to compare AMD patients and controls. ResultsWe found differences in white matter properties specific to OR white matter fascicles projecting to primary visual cortex locations corresponding to the location of retinal damage (fovea). Additionally, we show that the magnitude of white matter properties in AMD patients’ correlates with visual acuity. In sum, we demonstrate a specific relation between visual loss, anatomical location of retinal damage and white matter damage in AMD patients. Importantly, we demonstrate that these changes are so profound that can be detected using magnetic resonance imaging data with clinical resolution. The conserved mapping between retinal and white matter damage suggests that retinal neurodegeneration might be a primary cause of white matter degeneration in AMD patients. ConclusionsThe results highlight the impact of eye disease on brain tissue, a process that may become an important target to monitor during the course of treatment.