By Sade Oguntola
Now, with a simple test that involves looking for tiny changes in the retina, the light-sensitive area at the back of the eye that transmits incoming images to the brain for processing, it may be possible to predict individuals stroke risk years or even decades in advance, when a patient is healthy and happy.
New research, based on eye scans of nearly 50,000 people, shows that it is possible to successfully predict cardiovascular problems such as heart attacks and strokes simply from images of the retina, with no blood draws or other tests necessary.
A person’s chances of developing a stroke risk can be calculated using the retinal age interval. Those whose retinas appear older than their actual age were 2.3 times more likely to have a stroke in the next six years. It is in the journal BMC Medicine.
In fact, even one year difference in the patient’s real age and biological age of the retina increased the risk of stroke by five percent.
Retinal age interval is the difference between a patient?s actual age and the age of their retina as judged by the health of the blood vessels and tissue in the area.
The retina is the light-sensitive area at the back of the eye that transmits incoming images to the brain for processing. Doctors have found that changes to the tiny blood vessels can reflect the body?s overall health, including stroke and heart problems.
In addition, the various risk factors for stroke such as age, gender, smoking and blood pressure can be predicted from an eye scan.
A stroke is a serious life-threatening condition that occurs when the blood supply to part of the brain is cut off. Symptoms of stroke include trouble walking, speaking and understanding, as well as paralysis or numbness of the face, arm or leg.
The three major types of stroke in Africa are ischemic stroke, intracerebral haemorrhage strokes and subarachnoid haemorrhage.
Ischemic stroke also called dry stroke, which occurs when a blood vessel supplying blood to the brain is obstructed accounts for 60 -70 per cent of all cases of stroke. Intracerebral haemorrhage strokes result from bleeding occurring inside the brain and account for about 30 to 40 per cent of stroke cases while subarachnoid haemorrhages are the case in about five to 10 per cent of all stroke cases.
In fact, Dr. Rufus Akinyemi, a neurologist at the University College Hospital (UCH), Ibadan, who spoke at the ‘opening of a two-day African Stroke Leaders Summit with the theme ‘Operationalising a Roadmap for Reducing the Burden of Stroke in Africa: Vision 2030’, stated that stroke has now become the number one cause of death due to non-communicable diseases on the continent.
“Some decades ago, it was thought that hypertension and stroke are rare in Africa. But we know that stroke is a big problem on the African continent today. In fact, we like to describe Africa as the global stroke capital based on its huge burden because factors that drive it affect us from the womb to the tomb,” he said.
Major risk factors for stroke include high blood pressure, high cholesterol, and diabetes.
The World Health Organisation (WHO) says that early identification of those most at risk could give them precious time to address the risk factors, which could save many lives.
For the study, the researchers analysed the results using artificial intelligence. Over the next six years, nearly 300 men and women had strokes. The researchers found that a one-year increase in the biological age of the retina compared to the patient?s actual age increased the risk of stroke by 5 percent. Those with the largest age gap were 2.3 times more likely to have a stroke.
Artificial intelligence (AI) is a field that combines computer science and robust data sets, to enable problem-solving. The umbrella term encompasses the subfields of machine learning and the more recently developed deep learning, which itself is a subfield of machine learning. Both use AI algorithms to create expert systems that make predictions or classifications based on input data.
Although the idea of looking at the eyes to judge the health of the brain sounds unusual, it draws from a body of established research. Besides, things suggestive of many health problems like stroke, sickle cell disease and diabetes can be picked looking inside the eye, Dr Gboyega Ajayi, an eye specialist and Chairman, Eleta Eye Institute, Ibadan, said.
Dr Ajayi declared: “The eye is the mirror of the body. The changes in the blood vessels of the eye can be reflective of what is going on in the body like hypertension, diabetes and high cholesterol levels. By studying the blood vessels inside the eye, for instance, a diagnosis of sickle cell disease can be made and it is about 95 per cent accurate.”
Through artificial intelligence system, it is now possible to predict a persons? risk of many diseases like stroke and heart attack. This will afford the person the opportunity of controlling such risk factors to prevent or delay the onset of that disease.
The idea of looking inside the eyes to ascertain those that may likely develop stroke, Professor Mayowa Owolabi, a stroke expert at the UCH, Ibadan, said is possible because the retina is attached directly to the brain through the optic nerve and can be used as an indicator for changes in the brain itself.
The blood vessels within the retina can mirror what is going on the blood vessels within the brain; the damage to the blood vessels of the retina attributable to hypertension is called hypertensive retinopathy. It can tell the kind of damage that has happened to the blood vessels within the brain.
Stroke is all about the blood vessels of the brain. So, looking at the changes or the damage to the blood vessels of the brain, it will be possible to predict if a stroke is going to happen.
The caveat to predicting the likelihood that an individual will suffer a stroke through an eye scan is that the new method of scientific discovery is still in its early stages.
However, Professor Owolabi said “the message is that apart from checking blood pressure, blood sugar and cholesterol, which are the major risk factors for stroke, it might also be useful to have an annual eye examination based on this study.”
According to him, aside from checking the eye’s intraocular pressure, which is important to screen for glaucoma, the annual eye examination should include retina check for any blood vessel damage.
Worldwide, high blood pressure is the single most important risk factor for stroke. However, it’s still not possible to predict which high blood pressure patients are most likely to develop a stroke. Also, a person?s outcome following a stroke depends on how quickly they receive treatment once symptoms begin.
Worldwide, high blood pressure is the single most important risk factor for stroke. However, it’s still not possible to predict which high blood pressure patients are most likely to develop a stroke.
In a reaction, Dr Olufunmilola Ogun, an eye specialist at the UCH, Ibadan, stated that an increase in retinal age carries a higher risk of stroke is understandable because blood vessels of the retina change with age.
Blood vessels are all over the body, including the retina. It is very easy to see those at the back of the eyes and it is a reflection of what is happening inside the body, including inside the brain where stroke occurs.
“This technology that uses artificial intelligence to predict stroke risk is still a relatively new research and it is yet to become part of routine clinical practice. It certainly has a place because stroke is important and very prevalent in Nigeria and the number of cases is on the rise daily because our population is getting older,” Dr Ogun said.
Previously, a team of from the University of Leeds believes an artificial intelligence system is also capable of spotting whether someone will have a heart attack within the next year through a routine eye scan.
It is intriguing that artificial intelligence tools are opening the door to a cheap and simple screening programme for the world’s killer disease. It adds to evidence that the eyes are not just “windows to the soul,” but windows to overall health as well.
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