Biomarkers.

Area of Science:

• Neuroscience
• Ophthalmology
• Medical Imaging

Background:

• Optical coherence tomography (OCT) is a cost-effective tool for diagnosing ocular diseases.
• Its utility in detecting cerebral neurodegenerative diseases, like Alzheimer's disease (AD), is under investigation.
• Cerebral amyloid beta (Aβ) burden is a key biomarker for AD, often measured by positron emission tomography (PET).

Purpose of the Study:

• To systematically review the association between retinal degeneration, quantified by OCT, and cerebral Aβ burden measured by PET.
• To explore the potential of OCT in identifying early AD markers.

Main Methods:

• A systematic literature search was conducted across PubMed, Embase, Scopus, and Web of Science.
• Eleven studies involving Aβ+ and Aβ- subjects were included, analyzing OCT metrics (mRNFL, pRNFL, GCIPL) and PET-measured Aβ burden.
• Data extraction and synthesis were performed independently by two authors.

Main Results:

• The review included 221 Aβ+ and 535 Aβ- subjects across cognitively normal, preclinical AD, and cognitively impaired groups.
• Two studies found significant RNFL reduction with Aβ pathology; seven found non-significant alterations.
• Four studies reported significant GCIPL reduction with Aβ pathology; six found non-significant alterations.

Conclusions:

• The association between retinal changes and Aβ status is currently inconclusive.
• Retinal changes detected by OCT, particularly GCIPL reduction, may assist in early AD and Aβ positivity detection.
• Further standardized studies are required to validate OCT's clinical potential for AD diagnosis.