The investigators propose utilizing TDTCD to non-invasively measure CSFp in glaucoma/OHTN patients, IIH patients, and controls at various stages in treatment in order to further delineate the possible role of TPG in the pathophysiology of these conditions. The investigators believe this non-invasive approach has the potential to alter our current understanding and management of these disease processes, thereby assisting in the identification of at-risk patients more accurately, improving patients' quality of life.