September 17, 2026, 3:23 pm | Read time: 7 minutes
Atrial fibrillation is one of the most common heart rhythm disorders and is associated with an increased risk of strokes and heart failure. The condition is treatable but can often go undetected. This makes the findings of a recent study potentially valuable, as they suggest that signs of the condition can be detected in the eye, specifically on the retina.
Study on Eye Indicators of Atrial Fibrillation
From metabolic disorders such as diabetes to thyroid dysfunctions and high blood pressure–doctors can increasingly identify diseases through the eyes. This might also apply to atrial fibrillation.
Researchers from London investigated whether changes in the retina could indicate the widespread arrhythmia (heart rhythm disorder).1 It is one of the most common heart diseases and often leads to serious consequences such as stroke and heart attack. Diagnosing it can be challenging because the rhythm disorder often occurs sporadically, which means it might not be detected during an ECG.
The research team sought an additional way to detect signs of atrial fibrillation. They focused on the retina: As an easily accessible “window,” it could reveal changes in small blood vessels and the nervous system. The light-sensitive layer at the back of the eye has a finely branched vascular system and several distinct cell layers. Changes in these structures could provide clues about processes in the vascular and nervous systems.
Data from More Than 90,000 People Analyzed
For the study, researchers analyzed data from 90,190 people from two independent datasets. One source was the British AlzEye cohort, a research project for early disease detection using retinal scans. The AlzEye cohort includes patients aged 40 and older who were treated at Moorfields Eye Hospital in London between 2008 and 2018. The other data came from the UK Biobank, involving participants aged 40 to 69 who were enrolled in the population study between 2006 and 2010.
The study examined both the blood vessels and the thickness of various retinal layers. It was crucial to determine whether such changes could be detected before a later diagnosis of atrial fibrillation.
Combination of Cross-Sectional and Longitudinal Analysis
The research combined two analytical approaches: In the cross-sectional analysis, scientists compared the retinal features of people with and without existing atrial fibrillation. The longitudinal analysis explored whether certain changes were associated with the later onset of the heart rhythm disorder.
The retinal images were obtained using two imaging techniques. Optical coherence tomography (OCT) captured the individual layers of the retina, while color photographs of the eye’s fundus were used to assess the blood vessels. Part of the analysis was automated using an artificial intelligence-based method.
For the cross-sectional analysis, data from 50,651 people from AlzEye and 39,539 participants from the UK Biobank were available. The longitudinal analysis included 39,013 individuals from the UK Biobank who were healthy at the start. During an average follow-up period of 10.3 years, 838 of them developed atrial fibrillation–on average, after nearly four years.
Link Between Retinal Features and Atrial Fibrillation
In the AlzEye cohort, 5,735 of the 50,651 people studied had atrial fibrillation, representing 11.3 percent. They exhibited several retinal changes, most notably a reduced thickness of the so-called mGCIPL layer. This abbreviation stands for “macular ganglion cell-inner plexiform layer,” a tissue layer in the macula, or the “yellow spot.” It contains ganglion cells and their connections. In people with atrial fibrillation, this retinal layer was on average 1.96 micrometers thinner than in those without the heart rhythm disorder.
Other areas of the retina also showed reduced thickness. These included the nerve fiber layer of the macula (−0.69 micrometers), the inner nuclear layer (−0.57 micrometers), and the photoreceptor layer (−0.93 micrometers). Additionally, researchers found changes in certain features of the retinal vessels.
The association with a thinner mGCIPL layer was also observed in the independent UK Biobank cohort, where the layer was on average 1.19 micrometers thinner in people with existing atrial fibrillation.
Retinal Changes Preceded Atrial Fibrillation
The longitudinal analysis results were particularly interesting. Of the 39,013 people who initially had no known atrial fibrillation, 838 developed the heart rhythm disorder over time, on average after 3.95 years. Even after accounting for other factors such as age, gender, ethnicity, high blood pressure, diabetes, alcohol consumption, and smoking, a link between mGCIPL thickness and the later onset of atrial fibrillation remained. A one standard deviation thinner mGCIPL was associated with a 27 percent higher risk of a later atrial fibrillation diagnosis.
Significance of the Study
Importantly, the study shows a link between certain retinal features and atrial fibrillation. However, it does not prove that the heart rhythm disorder can be reliably diagnosed through a retinal image.
The researchers see their observations as a potential approach to identifying people at higher risk earlier. OCT images and retinal photographs are non-invasive and could provide additional information in the future. The actual diagnosis of atrial fibrillation still relies on detecting the heart rhythm disorder, including through an electrocardiogram (ECG). As previously explained, diagnosing atrial fibrillation can be challenging if it occurs only intermittently or without symptoms.
Study Author Explains Observations to FITBOOK
The researchers suspect that the thinner mGCIPL layer, a specific nerve cell layer of the retina, might be related to changes in the brain or small blood vessels. However, this aspect should not be viewed in isolation, according to study author Dr. Josef Huemer, as he explains to FITBOOK. “Thinning of the mGCIPL is not disease-specific but an indication of retrograde transsynaptic degeneration,” he explains. This refers to a form of nerve cell degeneration where damage can spread backward along interconnected nerve cells.
The expert also points to a possible link with small circulatory disorders in the brain. “Patients with atrial fibrillation have been found to have a higher number of small lacunar infarcts, which often go unnoticed.” This is particularly relevant because affected individuals often do not know they have atrial fibrillation and may not experience any symptoms.
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Two Different Changes–Two Possible Mechanisms
Regarding the observed retinal changes, the expert emphasizes: “Retrograde degeneration affects the mGCIPL, but not the mINL.” For the mINL, another retinal layer, he suspects a different mechanism.
“Thinning of the mINL was found in both the AlzEye and UK Biobank cohorts in patients with existing atrial fibrillation,” explains Dr. Huemer. His hypothesis: “This finding is caused by the strain on the cardiovascular system.”
There are parallels to other observations. Thinning of the mINL has been described, for example, in certain circulatory disorders of the deeper blood vessel layers of the retina. However, the expert emphasizes that further evidence is needed here. “Large-scale studies with OCT data are currently underway to gain more insights into mINL thinning in connection with cardiovascular diseases.”
Limitations
Since this was an observational analysis–and not a randomized controlled study–the results do not imply that a specific retinal change causes atrial fibrillation or can reliably predict the condition.
The study design also limits the conclusiveness of the results. Atrial fibrillation was recorded based on hospital admissions and, in the UK Biobank, additionally based on participant reports. As a result, especially intermittent or asymptomatic cases may have gone undetected.
Moreover, the two groups studied are not fully representative of the general population: UK Biobank participants are generally healthier, while the AlzEye cohort consists of patients from an eye hospital and thus more frequently exhibits systemic and eye diseases.
The authors currently view retinal imaging as a potential complementary tool. Whether it can reliably detect atrial fibrillation earlier must be confirmed in further studies.