Association of plasma glial fibrillary acidic protein and neurofilament light chain with retinal cell layer thickness: A cross-sectional study of ophthalmic surgical patients

BackgroundRetinal thickness has been associated with neurocognitive conditions such as Alzheimer's disease (AD).ObjectiveRetinal cell layer thickness was evaluated for associations with neurodegenerative protein biomarkers glial fibrillary acidic protein (GFAP) and neurofilament light chain (NfL) in plasma, vitreous humor, and aqueous humor.MethodsThis cross-sectional study included 50 patients who underwent vitrectomy and optical coherence tomography imaging of the inner macular ring (IM) and outer macular ring (OM). Associations between inner retinal cell layer thicknesses and GFAP or NfL levels were evaluated with linear regression adjusted for demographic and clinical factors. p-values less than 0.05 and with a false discovery rate less than 10% were considered significant.ResultsHigher plasma GFAP levels were significantly associated with a thinner retinal nerve fiber layer at the superior, nasal, and inferior OM as well as a thinner ganglion cell layer at the superior IM, inferior IM, temporal IM, nasal OM, and temporal OM. Plasma GFAP was also associated with a thinner inner plexiform layer at the nasal IM, inferior IM, temporal IM, nasal OM, and temporal OM. Plasma NfL was negatively associated with GCL thickness only in the superior IM.ConclusionsHigher plasma GFAP levels were associated with thinner inner cell layers, whereas plasma NfL levels showed a more limited association. These findings suggest that systemic astroglial activation may be associated with retinal structural changes.