retinal nerve fiber layer (RNFL) thickness changing has been reported in Alzheimer's Disease (AD) patients at an early stage, and has been demonstrated as a potential biomarker able to predict cognitive deterioration (Hinton DR et al., N Engl J Med 1986; London A et al. Nat Rev Neurol 2013; Chang LY et al., Alzheimers Dement 2014). However, whether RNFL thickness is correlated with cerebrospinal fluid (CSF) features of AD pathogenesis (e.g., Aβ and Tau) remains unclear. The investigators thus conducted this observational cohort study to test the correlation between RNFL thickness changing and CSF, to further validate RNFL as a potential AD biomarker.