Because of a shared ontogenic origin, the retina displays similarities to the brain and spinal cord in terms of anatomy, functionality, response to insult, and immunology. Hence, the retina can be approached as an integral part of the central nervous system. The occurence of ocular manifestations in several neurodegenerative pathologies, such as Alzheimer's disease and Parkinson's disease, accentuates the strong relationship between eye and brain. Particularly retinal changes can present a substrate for cerebral changes in these disorders. Offering a 'window to the brain', the transparent eye enables non-invasive imaging of these changes in retinal structure and vasculature. In this project, the potential of retinal biomarkers for e.g. Alzheimer's will be explored with the aim to overcome some of the hurdles in the current management of these pathologies, mainly the lack of techniques for patient screening and early diagnosis. The aim of this clinical trial is to correlate the retinal biomarkers for Alzheimer's with neuro-imaging, and cognitive function. Integrating the results will yield non-invasive retinal biomarkers for clinical research, screening, and follow-up of disease progression in various neurodegenerative disorders.