Could an eye test spot early signs of dementia?

Eye tests can pick up whether you’re long or short-sighted, identify glaucoma and monitor your eye health – and recent research suggests that your optician could also predict whether you are at risk of developing dementia.

The brain damage of dementia begins many years before any symptoms become apparent. A recent study suggests that there may also be characteristic changes in the back of the eye, that could be identified during specialist examination by an optician. Researchers discovered that people with thin retinas (a layer at the back of the eyeball) were more likely to have problems with mental function, in particular with tests assessing memory, reasoning and reaction time. Forgetfulness, confusion and problems with thinking are classic features of dementia, with symptoms gradually becoming worse over time.

The eye and dementia

Doctors already know that both the retina and the optic nerve, which connects the eye to the brain, are affected in people with well-established dementia. The brain and eye are closely connected, changes in the eye could mirror changes that occur in blood vessels in the brain. Eye tests may also spot the build-up of an abnormal protein, amyloid, in the retina. These protein deposits are believed to cause brain cell death in Alzheimer’s. The changes could be linked to the development of dementia and may be noticeable early on in the condition, even before the individual has noticed any problems.

In the most recent research, scientists measured the sensitive layer of tissue at the back of the eye in more than 30,000 individuals. They found that those with the thinnest retinas were more likely to perform poorly in mental tests and were also twice as likely to show a deterioration in function during follow-up assessments.

What would the eye test involve?

The eye test is inexpensive, painless and non-invasive. It’s called Optical Coherence Tomography or OCT. A detailed three-dimensional scan is taken of the tissue that lines the back of the eye. Light waves are reflected off the structural layers under the retina, to give a detailed, high-definition image of the area.

Why is early diagnosis of dementia important?

One of the lead researchers of the study, Professor Paul Foster, from the University College London Institute of Ophthalmology said that the eye tests could pick up people at high risk of developing dementia. Although there currently is no cure for dementia, early identification of the disease can make a difference to health, wellbeing and function.

Professor Foster said:

“It is likely that treatments will be more effective in slowing or stopping dementia at earlier stages of the disease. Also, by targeting people in the earlier stages, it should be possible to design better clinical trials for treatments that make a real difference and improve people’s lives.”

What happens now?

Although the research is promising, it is still at an early stage. Being told that you are likely to develop dementia can be devastating and life-changing, and many people with thin retinas won’t be affected, so an eye-test could only be used as part of a method of screening.

Dr Laura Phipps, from Alzheimer’s Research UK:

“While a diagnosis of dementia will always rely on results from a number of different tests, further studies should look at how sensitive OCT could be at identifying those most at risk of cognitive decline in the general population.”

Dr Phipps emphasised that more research is essential. The charity is co-funding a study looking at how eye scans could indicate dementia, Dr Phipps said that OCT scanning could potentially offer an inexpensive and straightforward method for detecting brain changes at an early stage.

Separate research suggests that hearing loss can play a role in dementia. Many opticians offer hearing tests too, so why not book yourself in for both tests?