However, sNfL levels are not disease specific and they increase in different systemic diseases (e.g. diabetes or kidney and heart failure) in the context of glymphatic and CSF fluid dynamic changes or in physiological conditions including normal aging.29 Elevation of NfL concentrations has also been found in the anterior chamber fluid, but not in the serum, of patients with glaucoma.30 This evidence concerns the gene NEFL and glaucoma.