UCL spots future heart problems in retinal scan data

A project at University College London (UCL) has studied an association between a patient's multimodal retinal imaging parameters and the later onset of atrial fibrillation in the same patient.

In collaboration with Moorfields Eye Hospital, the UCL researchers found that the heart condition could be correlated with structural changes in the retina detected four years previously. The study was published in PLOS Digital Health.

Atrial fibrillation is the most common heart rhythm disorder, and substantially raises the risk of stroke, heart failure and death. Because it often occurs intermittently it can be missed on a standard electrocardiogram (ECG), noted UCL, and as result many cases remain undiagnosed until a serious or life-threatening complication occurs.

Using high-resolution image data from the eye as an indication of other health conditions, often before those conditions have clearly manifested elsewhere, is a growing area of study, and has been christened oculomics.

While collecting high-resolution imaging data related to age-related macular degeneration (AMD), glaucoma and diabetic retinopathy, UCL and Moorfields have previously identified biomarkers for Parkinson’s disease, Alzheimer’s disease, schizophrenia, cardiovascular disease and stroke.

"Because the retina shares structural and vascular similarities with the brain and heart, changes visible on routine eye scans may reflect broader changes occurring elsewhere in the body," wrote the project in its paper.

Retinal imaging catching those most at risk of atrial fibrillation

In its new study the team analysed optical coherence tomography (OCT) scans and colour retinal photographs from two datasets, a Moorfields cohort with over 50,000 patients, and a UK Biobank cohort of around 40,000 participants. A number in both groups had gone on to experience atrial fibrillation, recorded in their medical history.

Across both datasets, people with atrial fibrillation consistently had structural changes to one key inner retinal structure: the macular ganglion cells and inner plexiform layer, or mGCIPL. This layer at the back of the eye is made up of nerve cells that connect the eye to the brain, and the thinner this particular layer was, the more likely the person was to be diagnosed with atrial fibrillation. 

This thinning was observed among patients who did not have atrial fibrillation when the retina images were taken but who went on to develop it four years later, suggesting that retinal changes may be detectable at a stage when the heart condition has no symptoms. UCL numbers say that "each standard deviation decrease in mGCIPL thickness was associated with a significant 27 percent increased hazard of atrial fibrillation."

UCL's current theory is that the thinning observed in retinal imaging data could result from ischaemic, or "mini," strokes in the brain reducing blood flow to the retina, or microvascular events associated with atrial fibrillation before full manifestation of the condition. Changes to the blood flow in the retina nerve cells caused by these events could lead to the observed thinning, before the underlying issues reveal themselves more drastically.

"If confirmed in further research, our findings raise the possibility that routine eye examinations could in future help identify people who would benefit from closer cardiac assessment, potentially enabling earlier treatment with therapies known to reduce the risk of stroke," commented UCL's Josef Huemer.