Unlocking Retina’s Potential

Frequently referred to as a “window to the brain”, the retina has been known for decades to offer up biomarkers for many diseases, ocular and otherwise. But it is only now that the full extent of this observation is being realized. Thanks to advances in optical coherence tomography (OCT) screening, imaging specialists in 2024 have the means to identify the early indicators of many conditions. In addition, research projects around the world are laying the foundations to make optimum use of new drugs becoming available (drugs such as lecanemab and donanemab for Alzheimer's, Syfovre and Izervay for geographic atrophy, and Ocrelizumab for MS), which will have a profound effect on millions of lives.

“In the future [optometrists and ophthalmologists] could be examining more than eye health, by looking at changes to brain health, risk of stroke and cardio-vascular disease that may be five or ten years away in their patient’s future,” says Tom MacGillivray, Principal Investigator in the Centre for Clinical Brain Sciences, University of Edinburgh, UK. “This [development] could elevate the entire role of optometry, and we need clinical pathways to address this very soon. We have the potential to spot signs of change years ahead, opening the door for many new treatments.”

MacGillivray adds that optometrists can now “see the in-vivo workings of the brain and the micro-vascularity at work”, meaning that signs of systemic, metabolic and neurodegenerative disease can be detected through the eye – diseases such as Alzheimer’s, Parkinson’s Disease, diabetes, and Huntington's Disease.

Retinal and choroidal cellular layers are providing detailed measurements and are under extensive scrutiny. They are being monitored over time with fast, non-invasive OCT, a modality that is easily integrated into existing workflows.

This immense potential for wider healthcare disease prediction, diagnosis, and monitoring heralds a new era of medicine, a concept that is often labeled “oculomics” or “computational ophthalmology”.

Multiple Sclerosis and Alzheimer’s Disease progression monitoring via retinal scans is now ten years down the line, with MacGillivray’s research providing valuable findings which will aid future diagnosis and drug development.

“Five years ago we started the Future MS longitudinal study, looking at 230 newly diagnosed patients from throughout Scotland,” explains MacGillivray. “Our PhD student is segmenting the retinal layers, and looking at angiography in relation to the patients’ frailty and cognitive scores. We are also looking at patients who are at risk of stroke and Parkinson’s to examine the different signatures of conditions affecting the brain in the retinal tissues and cells. The unique data sets for neuro-degenerative diseases are clearly defined through deep clinical phenotyping.”

This type of retinal screening gives contextual changes that can’t be evaluated using a traditional bran scan, MacGillivray adds. “By examining these patients, particularly with a family history, they can be assessed and directed to lifestyle changes or prescribed medication in the future. In the next five years we expect to be tracking people who are much younger.”

MacGillivray believes that the Heidelberg Engineering SPECTRALIS system “delivers one of the best OCT views possible” for this type of scanning. “We can’t do anything without scan data, and highly detailed imaging technology brings many disciplines together,” he says. “Looking at how the retina changes over time, how patients are in themselves, and how prescribed medication affects patients, are all facilitated by OCT.

The University of Edinburgh is working alongside Duke University, North Carolina, US, to collaborate on projects focusing on early and late-stage Alzheimer’s and Parkinson’s diseases, as well as joining forces with other UK-based universities in Belfast, Dundee, and Cambridge for a number of studies. One such study, the PREVENT Dementia study – a study aimed at identifying the earliest signs of dementia in UK and Ireland that is part-funded by the Alzheimer’s Association – has been running for over a decade and has more than 700 participants. “We are monitoring people in their 50s and 60s before any clinical symptoms appear,” says MacGillivray. “Cambridge leads the MRI brain scanning and we are using retinal scans alongside this to identify micron level changes to nerve tissue and blood vessels.”

2003 saw the formation of VAMPIRE (Vascular Assessment and Measurement Platform for Images of the Retina), a collaborative initiative that is focused on developing software and methodologies to advanced retinal imaging. Now in its 21st year, the VAMPIRE research group is driving biomarker discovery and providing valuable insights into the microvasculature of brain and holistic health. Providing technical expertise, and funded by UK research grants, VAMPIRE is playing a crucial role in advancing clinical applications relating to vascular health and disease.

“Finding people best suited for clinical trials, and seeing what changes there are in the blood vessels and tissues of the retina, is opening up targets for new therapies across a broad range of morbidities,” MacGillivray exclaims. “It is an extremely exciting time to be working in this field.”

This article first appeared in The New Optometrist.