A novel, noninvasive eye imaging system able to detect pathological markers of Alzheimer’s disease (AD) has been presented in a proof-of-concept study from researchers at Cedars-Sinai Medical Center (CA, USA) and NeuroVision LLC (CA, USA).
The technology scans the retina for beta-amyloid protein (Aβ) deposits, which represent the status of deposits in the brain. Previous research has suggested that Aβ accumulation is an early event in disease development, highlighting its potential as an early biomarker suitable for screening. Currently, Aβ is only detectable by invasive and expensive processes such as cerebrospinal fluid analysis or PET scans. These techniques are impractical for routine or large-scale screening.
“This clinical trial is reinforced by an in-depth exploration of the accumulation of Aβ in the retina of Alzheimer’s patients versus matched controls, and a comparison analysis between retina and brain pathologies,” explained Maya Koronyo-Hamaoui (Cedars-Sinai Medical Center). “Findings from this study strongly suggest that retinal imaging can serve as a surrogate biomarker to investigate and monitor AD.”
The imaging system performs autofluorescence imaging of the retina using specialized ophthalmic camera technology from NeuroVision LLC.
The new study presented detailed analysis of AD pathology in the retina from 37 deceased patients; 23 had confirmed AD and 14 were controls. The proof-of-concept trial included 16 live patients and established a probe formulation, protocol and scoring system (the retinal amyloid index [RAI]).
Histological examination demonstrated a 4.7-fold increase in retinal plaque burden in AD patients, along with neuronal loss. Retinal plaque status mirrored that of the brain, particularly in the primary visual cortex. The deposits were often associated with blood vessels and occurred in ‘hot spots’ in particular regions and layers. The feasibility trial demonstrated a 2.1-fold increase in RAI scores for AD patients versus controls.
Further research is required to both confirm Aβ’s exact potential as a biomarker and to replicate the trial with a larger cohort. “Such retinal amyloid imaging technology, capable of detecting discrete deposits at high resolution in the CNS, may present a sensitive yet inexpensive tool for screening populations at risk for AD, assessing disease progression, and monitoring response to therapy,” concluded the authors.
Sources: Koronyo Y, Biggs D, Barron E et al. Retinal amyloid pathology and proof-of-concept imaging trial in Alzheimer’s disease. JCI Insight 2(16), 93621 (2017); www.eurekalert.org/pub_releases/2017-08/prpl-css082217.php