Hyperspectral retinal imaging shows amyloid‐like deposits in preclinical Alzheimer’s disease

Abstract

AbstractBackgroundBrain beta‐amyloid deposits in Alzheimer’s disease (AD) are associated with retinal beta‐amyloid deposits post‐mortem, yet, findings from imaging the live human retina provide inconclusive evidence due to confounding factors such as drusen found in age‐related macular degeneration [(AMD), (Kayabasi 2014, Koronyo‐Hamaoui 2017)]. We therefore aimed to identify drusen and retinal amyloid‐like deposits via hyperspectral imaging.MethodCognitively normal (n=45) older adults, aged 50‐85 years with known neocortical amyloid burden (NAB) including those at‐risk for AD (SUVR≥1.35), were recruited from our study cohorts in Sydney, New South Wales. All participants completed imaging in the spectral range of 450 to 900nm wavelength at 5nm steps. 11 participants completed optical coherence tomography to confirm presence/absence of drusen. Raw hyperspectral images were visually scanned to identify retinal deposits.ResultMatched to our reference images, we identified retinal hyperintense ‘nano dots’. The spectral range of drusen and nano dots was between 500 to 635 nm and 450 to 600 nm respectively. Drusen was more around the macula in a clustered fashion. nano dots were seen in abundance in the superior quadrant, scattered along the blood vessels and appeared smaller with well distinct margin. In participants with no history of AMD (n=30), the visual identification of nano dots was possible for 77% in high NAB and no nanodots were visually identified in 70% in low NAB group participants.ConclusionFurther investigation is required to examine the nano dots to determine whether they have diagnostic significance.