More than 850,000 people in the UK have dementia, the umbrella term for a collection of progressive diseases that affect the brain, with symptoms including severe memory loss and difficulty with problem solving or language.

There is no cure for dementia but those who show early stage signs can implement lifestyle changes to minimise its damage.

Drugs are also being developed which experts hope will be able to ward it off – but, again, these will only work if people are diagnosed early. Unfortunately, most people are diagnosed in the late stages of the disease.

Recently, however, scientists have announced big breakthroughs in this field through studying the back of the eye, which can act as a window to the brain and display signs of changes at the same time as they are taking place deep within the brain circuits. Their findings means that, in future, opticians may be able to look for signs of dementia during routine annual eye checks, years before people begin to display symptoms.

 

Eye scans

 

Two scientific teams exploring the link between vision and dementia presented their findings at the Alzheimer’s Association International Conference (AAIC) in Toronto in July. London’s Moorfields Eye Hospital in London and Oxford University revealed how they used scans to measure the precise thickness of a layer of neurons on the retina at the back of the eye. Researchers found that people who had a thinner layer of neurons were more likely to perform poorly in cognitive tests — a clear warning that they may be in the early stages of dementia. “This demonstrates the potential utility of the eye as a non-invasive measure of neuronal loss which is linked to cognitive performance,” says Fang Ko, MD, from Moorfields, “and provides a possible new biomarker for studies of neurodegeneration.”

Researchers have found a remarkable link between vision and dementia

“Medical technology has improved so much over the last few years,” says Dr Susan Blakeney, Clinical Adviser from the College of Optometrists. “The equipment that is available now to measure the thickness of the retina is becoming more mainstream. It's not found in every optometric practice at the moment — but in the years ahead we could see it appearing in many, if not most of them. It's a non-evasive test and simple to do: a bit like a taking a 3D photograph.”

 

Further imaging

 

Scientists at Waterloo University in Canada discovered that people with severe Alzheimer’s disease had deposits of a protein called amyloid on their retinas. Amyloid, thought to be one of the key causes of Alzheimer’s — the most common type of dementia — often forms in the brain; but this is the first time that scientists have found it is also visible on the eye. The work was completed using high-imaging techniques which researchers now aim to adapt for use with standard opticians’ instruments.

The Alzheimer's Society — which launched the Dementia Friends programme in 2013, the biggest ever initiative to change people’s perceptions of dementia — has welcomed the findings. “Eye tests are fairly common for older people, so there is great potential to incorporate additional tests into their regular check-up,” says Dr Clare Walton, Research Manager at the society. “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.”