3D eye scans widely used in high street opticians could help to identify people at high risk of developing Parkinson’s disease up to seven years before they have symptoms, data has suggested.
The finding added to growing evidence that the use of eye scan data could help to detect neurodegenerative diseases and followed recent studies suggesting that the technique could help to identify early signs of Alzheimer’s, multiple sclerosis and schizophrenia. This emerging field of research, known as “occulomics”, is also being investigated as a means of identifying individuals with a propensity for cardiovascular disease or diabetes.
Doctors have long considered the eyes a window to wider health, with visual changes, yellowing eyes or bulging eyeballs potentially suggestive of conditions such as diabetes, liver damage or thyroid disease.
More recently, a type of 3D scan known as optical coherence tomography (OCT) that uses light waves to take cross-section pictures of the retina – an area of nerve tissue at the back of the eye that senses light and sends signals to the brain – has been widely introduced at high-street opticians to help identify eye diseases such as glaucoma and age-related macular degeneration.
With the advent of big data, artificial intelligence (AI) and parallel advances in retinal imaging, scientists are now investigating whether other conditions might be detectable by studying this tissue.
Pearse Keane, a professor of artificial medical intelligence at University College London and Moorfields eye hospital, said: “The eye is the only part of the body where you can directly visualise the microvascular circulation [the flow of blood through the tiniest vessels]. If you have changes in your blood or cardiovascular system, those changes may be manifested in the retinal blood vessel.
“The retina is also part of your central nervous system; when it forms in the embryo, it is outpouching from the neural tissue that develops. The phrase that people use is the retina is an approachable part of the brain. It is the only part of the brain that you can directly visualise without opening a window in someone’s skull.”
Keane and his colleagues are investigating the potential of retinal imaging to detect a range of different conditions, from schizophrenia and cardiovascular disease to Alzheimer’s disease. To do this, they are linking anonymised data from thousands of Moorfields eye hospital patients with the national NHS database, which logs every UK hospital visit, meaning that if someone has an eye scan at Moorfields, their future health outcomes can be tracked.
In the current study, they used AI to compare OCT eye scan data from 700 patients who went on to develop Parkinson’s disease with more than a hundred thousand patients who did not. This revealed differences in the thickness of the inner retinal cell layer, which appeared to be associated with the development of Parkinson’s.
They also examined data from 67,311 volunteers enrolled in the UK Biobank study – an online database of anonymised medical and lifestyle records from hundreds of thousands of UK participants – who had undergone retinal imaging. “Using this data we were able to show that these changes could be seen up to seven years in advance among people who went on to develop Parkinson’s,” Keane said. The research was published in Neurology.
Although Keane stressed that further studies were needed, and that the technology was probably still a number of years away from being able to accurately diagnose Parkinson’s, in the future patients might be able to go for a routine eye check and have early signs of other diseases picked up.
Dr Siegfried Wagner of the UCL Institute of Ophthalmology and Moorfields eye hospital, who led the study, said: “Finding signs of a number of diseases before symptoms emerge means that, in the future, people could have the time to make lifestyle changes to prevent some conditions arising, and clinicians could delay the onset and impact of life-changing neurodegenerative disorders.”
Claire Bale, an associate director of research at Parkinson’s UK, said: “Parkinson’s is a condition that develops gradually over time and research suggests damage could begin many years before symptoms appear. Intervening earlier to stop the loss of precious brain cells is the key to preventing the condition.
“This research offers hope that eye scans could be used to identify people at risk of developing Parkinson’s to enable early treatment. And because the eye scans analysed in this study are non-invasive, and already in routine use, this could be easily put into practice in the NHS.”
