Background:
Recent work on Alzheimer's disease (AD) diagnosis focuses on neuroimaging
modalities; however, these methods are expensive, invasive, and not available to all patients. Ocular
imaging of biomarkers, such as drusen in the peripheral retina, could provide an alternative
method to diagnose AD.
Objective:
This study compares macular and peripheral drusen load in control and AD eyes.
Methods:
Postmortem eye tissues were obtained from donors with a neuropathological diagnosis of
AD. Retina from normal donors were processed and categorized into younger (<55 years) and older
(>55 years) groups. After fixation and dissection, 3-6 mm punches of RPE/choroid were taken in
macular and peripheral (temporal, superior, and inferior) retinal regions. Oil red O positive drusen
were counted and grouped into two size categories: small (<63 μm) and intermediate (63-125 μm).
Results:
There was a significant increase in the total number of macular and peripheral hard drusen in
older, compared to younger, normal eyes (p<0.05). Intermediate hard drusen were more commonly
found in the temporal region of AD eyes compared to older normal eyes, even after controlling for
age (p<0.05). Among the brain and eye tissues from AD donors, there was a significant relationship
between cerebral amyloid angiopathy (CAA) severity and number of temporal intermediate hard
drusen (r=0.78, p<0.05).
Conclusion:
Imaging temporal drusen in the eye may have benefit for diagnosing and monitoring progression
of AD. Our results on CAA severity and temporal intermediate drusen in the AD eye are novel.
Future studies are needed to further understand the interactions among CAA and drusen formation.
Contrast integration over area is extensive: A three-stage model of spatial summation