Could an eye test help diagnose dementia?

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 got lose their memory.

More than 500,000 people in Britain have dementia, a figure which is on the rise. However, most of them are only diagnosed after it is too late for treatment or lifestyle changes to make much impact. This new test creates the possibility for early intervention, limiting the extent of the damage posed by this devastating disease.

Now this exciting research breakthrough raises the prospect that opticians could soon look out for signs of dementia during annual eye checks.

The researchers used high definition OCT eye scans to measure, in minute detail, the thickness of a layer of neurons on the retina at the back of the eye among 33,000 British patients aged 40 – 69. They also carried out a series of tests on memory, reaction time and reasoning.

They found that people who had a thinner layer of neurons were more likely to perform poorly on the cognitive tests – a clear warning sign they might be undergoing the early stages of dementia.

The OCT scanning machine, which uses light waves to draw a detailed picture of the back of the eye, is already used by many ophthalmologists and could easily be built into a standard eye exam.

Study leader Dr Fang Ko, of Moorfields Eye Hospital, said:

Our findings show a clear association between thinner macular retinal nerve fibre layer and poor cognition in the study population.  This provides a possible new biomarker for studies of neurodegeneration.

Dr Clare Walton, research manager at the Alzheimer’s Society, said:

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. 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.