Eye tests that help diagnose dementia
30 January 2020
Researchers from Moorfields Eye Hospital and Oxford University have identified a simple test that could be used to spot Alzheimer’s disease years before people begin to lose their memory.
Alzheimer’s disease is one of 200 types of dementia, a range of conditions that affect the brain. More than 800,000 people in Britain have dementia today, and that number is growing.
Unfortunately, most are diagnosed too late for treatment and researchers have been working for years to find a way to prevent this happening.
What is dementia?
The brain is made up of nerve cells (neurones) that communicate with each other by sending messages.
Dementia damages the nerve cells in the brain so messages can’t be sent from and to the brain effectively, which prevents the body from functioning normally.
A new test discovered by researchers from Moorfields Eye Hospital and Oxford University suggests that annual eye checks might be one way of spotting dementia sooner, creating the possibility for early intervention.
Dr Clare Walton, who is a research manager at Alzheimer’s Society, explains:
Changes in the brain associated with dementia can begin several years before any memory symptoms appear. This research suggests some of these changes happen in the retina of the eye too, which could give us a relatively easy, non-invasive way to spot them early.
If it works, testing like this could limit the extent of the damage posed by this devastating disease for thousands of people.
Using a combination of high definition eye scans and cognitive testing, researchers conducted the study on a group of 33,000 British patients aged between 40 and 69 - a core age group at risk of developing dementia.
They used a tool called an OCT scanning machine to scan a layer of nerve cells (neurons) at the back of the eye (the retina) and carried out a series of tests on memory, reaction time and reasoning.
Results and next steps
Importantly, this study showed that people who had a thinner layer of neurons on the retina were more likely to perform poorly on the cognitive tests – a clear warning sign they might be undergoing the early stages of dementia.
Study leader Dr Fang Ko, from Moorfields Eye Hospital, has described this finding as “a possible new biomarker for studies of neurodegeneration.”
Researchers suggest that it would also be an easy transition to build this type of testing into standard eye exams, as the machine used for scanning the eyes is already used by many ophthalmologists.
Eye tests are fairly common for older people, so there is great potential to incorporate additional tests into their regular check-up. These tests could help to identify people at risk of dementia who would benefit from further investigation but will not become a primary way to diagnosis the condition.
Dr Clare Walton, research manager at Alzheimer’s Society