GFAP and Alzheimer disease: Thus, in this cross-sectional pilot study, we aimed to examine the layer thicknesses across the entire retina, including the inner retina, the outer retina, and the choroid, in relation to plasma Aβ42/40 ratio, p-tau217, p-tau181, GFAP, and NfL levels in cognitively healthy (CH) elderly individuals at risk for AD.