MAPT and Alzheimer disease: We conducted quantitative analysis of retinal CitR209-tau in a cohort of donors with MCI (n = 8, mean age 89.13 ± 5.22 years, 4 females/4 males), AD (n = 21, mean age 82.81 ± 13.40 years, 10 females/11 males), and NC controls (n = 18, mean age 80.72 ± 7.89 years, 9 females/9 males).