Comparison of Retinal Structural and Neurovascular Changes between Patients with and without Amyloid Pathology

Area of Science:

• Ophthalmology
• Neurology
• Biomarkers

Background:

• Alzheimer's disease (AD) involves beta-amyloid (Aβ) plaques.
• The anterior visual pathway, including retinal structures, may reflect brain pathologies.
• Investigating retinal changes could offer insights into early AD detection.

Purpose of the Study:

• To determine if impaired retinal structures and microvasculature correlate with Aβ pathology in Alzheimer's disease dementia (ADD) and mild cognitive impairment (MCI).
• To compare retinal factors between subgroups with positive (A+) or negative (A-) amyloid biomarkers.

Main Methods:

• Recruited patients with ADD, MCI, and cognitively unimpaired (CU) controls.
• Assessed Aβ status using amyloid positron emission tomography or cerebrospinal fluid.
• Measured retinal circumpapillary retinal nerve fiber layer thickness (cpRNFLT), macular ganglion cell/inner plexiform layer thickness (mGC/IPLT), and macular microcirculation using OCT and OCT angiography.

Main Results:

• Retinal structural and vascular factors decreased significantly from CU to MCI to dementia.
• A+ individuals showed significantly lower microcirculation in temporal macula regions compared to A-.
• No significant differences in structural or vascular parameters were found between A+ and A- dementia patients.
• cpRNFLT was unexpectedly greater in A+ MCI patients than A- MCI patients.
• mGC/IPLT was lower in A+ CU individuals than A- CU individuals.

Conclusions:

• Retinal structural changes may appear in preclinical and early dementia stages but lack specificity for AD pathophysiology.
• Decreased temporal macula microcirculation shows potential as a biomarker for underlying Aβ pathology.