Increased retinal Aβ42 deposition correlates with cerebral amyloid plaque burden in Alzheimer’s patients. (A) Representative micrographs from an AD brain and (B) flat-mount retinas from a cognitively normal (CN) subject and (C) AD patient stained with anti-Aβ42 mAb (12F4). Although smaller in size, retinal Aβ plaques are similar in morphology to brain plaques. Scale bar: 20 μm. (C) High-magnification images reveal diffuse, compact, and “classical” mature plaque morphology of retinal Aβ aggregates. Scale bar: 10 μm. (D) Quantitation of retinal Aβ42 plaque burden, measured by 12F4 immunoreactive area, in AD patients (n = 8) and sex-/age-matched CN control subjects (n = 7). Data shown as group mean ± SEM. **P < 0.01, unpaired 2-tailed Student’s t-test. (E,F) Pearson’s correlation coefficient tests between retinal Aβ42 plaque load (12F4-immunoreactivity) and mean cerebral neuritic plaque burden (e; r = 0.87, P = 0.0048, n = 8; severity score of Gallyas silver staining) or regional plaque burden either in the entorhinal (F; black symbols; r = 0.84, P = 0.0092, n = 8) or primary visual cortex (F; orange symbols; r = 0.84, P = 0.0097, n = 8). Reproduced from Koronyo et al. (2017) with permission of ASCI via Copyright Clearance Center.