MAPT and Cognitive impairment: Growing evidence indicates the presence of AD-related pathological features in the retinas of patients with mild cognitive impairment (MCI due to AD) and/or AD dementia, including various abnormal Aβ and tau species, vascular damage, micro- and macro-gliosis, and neurodegeneration [2, 5, 7, 8, 16, 17, 22, 28, 30–32, 38, 40, 43, 46, 48, 63–65, 70, 73, 74, 84, 88, 89, 98, 107, 108, 110–112, 118, 129, 131].