Retinal Microstructural and Microvascular Changes in Alzheimer Disease: A Review

Area of Science:

• Ophthalmology
• Neurology
• Biomarker Discovery

Background:

• Alzheimer disease (AD) involves preclinical neurodegeneration before symptoms appear.
• Mild cognitive impairment (MCI) often precedes AD, sharing similar early pathological changes.
• The retina, as part of the central nervous system, may exhibit AD-related pathology.

Purpose of the Study:

• To review the relationship between Alzheimer disease and retinal pathology.
• To explore the utility of optical coherence tomography (OCT) and OCT angiography (OCTA) in detecting these retinal changes.
• To assess the potential of retinal biomarkers for early AD detection and monitoring.

Main Methods:

• Review of studies investigating retinal changes in Alzheimer disease using OCT and OCTA.
• Correlation analysis of retinal findings with brain imaging (MRI, PET) and neuropsychological tests.
• Summarization of common retinal biomarkers associated with AD.

Main Results:

• Common findings in AD patients include retinal nerve fiber layer thinning and reduced macular thickness.
• Enlarged foveal avascular zone and decreased vascular density in retinal capillary plexuses are observed.
• Retinal changes correlate with cerebral atrophy, amyloid load, and cognitive decline.

Conclusions:

• Retinal microstructural and microvascular abnormalities show potential as biomarkers for early AD detection.
• Ophthalmic imaging with OCT and OCTA can aid in clinical monitoring of AD.
• Standardized protocols for in vivo ophthalmic imaging are needed for AD and MCI research.