Eye reflects brain: A symbolic image representing the connection between retinal health and cognitive function.

The Eyes May Have It: How Retinal Scans Could Help Detect Cognitive Decline

Beau Callahan in Health & Wellness August 2025 • 4 min read.

"New research explores the link between retinal nerve fiber layer thickness and cognitive function, offering potential for early Alzheimer's detection."

Cognitive decline, particularly dementia and Alzheimer's disease (AD), poses a significant global health challenge. With millions affected worldwide, the search for early detection methods is crucial for potential preventative interventions. While definitive AD diagnoses often occur postmortem, the quest for accessible and non-invasive biomarkers to identify precursor syndromes is ongoing.

The eye, specifically the optic nerve and retina, offers a unique window into the central nervous system (CNS). Unlike other cranial nerves, the optic nerve is directly connected to the CNS, making it a potential indicator of neurological health. Recent advancements in ophthalmic imaging have enabled accurate measurements of the retinal nerve fiber layer (RNFL), sparking interest in its potential as a biomarker for cognitive function.

Inspired by this premise, a study published in Investigative Ophthalmology & Visual Science explored the relationship between RNFL thickness and cognitive function in a large cohort of older British adults. The results shed light on the intriguing possibility that changes in the retina could reflect broader changes occurring in the brain.

Decoding the EPIC-Norfolk Study: Retinal Clues to Cognitive Health

Eye reflects brain: A symbolic image representing the connection between retinal health and cognitive function.

The EPIC-Norfolk study, a large-scale prospective cohort study in the United Kingdom, provided the data for this investigation. Researchers assessed the cognitive function and RNFL thickness of 5,563 participants with an average age of 67 years. Cognitive assessments included a range of tests evaluating memory, attention, language, and learning. RNFL thickness was measured using the Heidelberg Retina Tomograph (HRT), a sophisticated imaging device that creates three-dimensional images of the optic nerve head.

The study revealed a significant association between HRT-derived RNFL thickness and cognitive test scores. Specifically, thicker RNFL was correlated with better performance on the Mini-Mental State Examination (MMSE), Hopkins Verbal Learning Test (HVLT), and the National Adult Reading Test (NART). These tests assess global cognitive function, recognition, learning, episodic memory, and premorbid intelligence, respectively. This suggests that individuals with healthier retinas, as indicated by RNFL thickness, tended to perform better on cognitive assessments.

Better performance on the SF-MMSE cognitive assessment tool.
Better performance on the HVLT cognitive assessment tool.
Better performance on the NART cognitive assessment tool.
Thicker retinas may correlate to better overall cognitive function.

While these findings are promising, it's crucial to interpret them with caution. The associations observed were relatively weak, meaning that RNFL thickness alone cannot accurately predict cognitive function. The researchers emphasize that further research is needed to confirm these associations, clarify the underlying biological mechanisms, and identify other potential biomarkers.

Looking Ahead: The Future of Retinal Imaging in Cognitive Assessment

The EPIC-Norfolk study provides valuable insights into the potential link between retinal health and cognitive function. While further research is necessary, these findings suggest that monitoring RNFL thickness could serve as a non-invasive and affordable tool for identifying individuals at risk of cognitive decline. As technology advances, retinal imaging may play an increasingly important role in the early detection and management of neurodegenerative diseases like Alzheimer's disease.

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This article is based on research published under:

DOI-LINK: 10.1167/iovs.16-19067, Alternate LINK

Title: Retinal Nerve Fiber Layer Measures And Cognitive Function In The Epic-Norfolk Cohort Study

Subject: General Medicine

Journal: Investigative Opthalmology & Visual Science

Publisher: Association for Research in Vision and Ophthalmology (ARVO)

Authors: Anthony P. Khawaja, Michelle P. Y. Chan, Jennifer L. Y. Yip, David C. Broadway, David F. Garway-Heath, Robert Luben, Shabina Hayat, Fiona E. Matthews, Carol Brayne, Kay-Tee Khaw, Paul J. Foster

Published: 2016-04-19

Everything You Need To Know

What was the focus of the research regarding retinal scans and cognitive decline, and what data and tools were used?

The study examined the connection between the thickness of the retinal nerve fiber layer (RNFL) and cognitive functions like memory, attention, and learning. Researchers used data from the EPIC-Norfolk study, assessing participants' cognitive performance using tests like the Mini-Mental State Examination (MMSE), Hopkins Verbal Learning Test (HVLT), and National Adult Reading Test (NART). RNFL thickness was measured using the Heidelberg Retina Tomograph (HRT).

According to the EPIC-Norfolk study, what specific correlations were found between retinal health and cognitive performance, and what tests were used to determine this?

The EPIC-Norfolk study revealed a correlation between retinal nerve fiber layer (RNFL) thickness and cognitive test scores. Thicker RNFL, as measured by the Heidelberg Retina Tomograph (HRT), was associated with better performance on cognitive assessments such as the Mini-Mental State Examination (MMSE), Hopkins Verbal Learning Test (HVLT), and the National Adult Reading Test (NART). These tests measure global cognitive function, recognition, learning, episodic memory, and premorbid intelligence.

What do the Mini-Mental State Examination (MMSE), Hopkins Verbal Learning Test (HVLT), and National Adult Reading Test (NART) each measure, and how did they contribute to the study's findings?

The Mini-Mental State Examination (MMSE) assesses global cognitive function, the Hopkins Verbal Learning Test (HVLT) measures recognition, learning, and episodic memory, and the National Adult Reading Test (NART) evaluates premorbid intelligence. These tests, used in conjunction with retinal nerve fiber layer (RNFL) measurements from the Heidelberg Retina Tomograph (HRT) in the EPIC-Norfolk study, helped researchers correlate retinal health with cognitive performance.

How reliable is retinal nerve fiber layer (RNFL) thickness as a standalone indicator of cognitive decline, and what limitations were identified in this research?

While the EPIC-Norfolk study suggests a link between retinal nerve fiber layer (RNFL) thickness and cognitive function, it's important to note that the observed associations were relatively weak. RNFL thickness alone isn't a definitive predictor of cognitive decline or conditions like Alzheimer's disease. Further research is necessary to confirm these associations, understand the underlying biological mechanisms, and identify additional biomarkers for more accurate predictions.

In what ways could future research expand upon the findings regarding retinal imaging and cognitive assessment to better understand and detect neurodegenerative diseases?

Future research could involve longitudinal studies to monitor changes in retinal nerve fiber layer (RNFL) thickness over time and correlate these changes with cognitive decline. Combining retinal imaging with other biomarkers, such as cerebrospinal fluid analysis or PET scans, could improve the accuracy of early Alzheimer's disease detection. Additionally, exploring genetic factors and lifestyle influences that affect both retinal and brain health could provide a more comprehensive understanding of the link between eye and brain health.