The purpose of this study is to evaluate the effects of multiple sclerosis (MS) lesions in the visual pathway and how they contribute to nerve cell loss in the retina and impact visual function over time. Participants will undergo a research visit to review and collect demographic and medical history, annual brain MRI exams, and annual research blood draw, as well as clinical disability assessments and visual examinations every 6 months in order to investigate the risk of visual and clinical disability associated with specific MS brain lesions and investigate a process called “trans-synaptic degeneration,” which refers to the spread of nerve cell death from one nerve cell to adjacent cells across the connections between these cells called synapses. The study aims to design better methods to monitor visual function and detect nerve cell loss in the retina due to MS lesions.