SINGAPORE- Medical researchers in Singapore are assessing the possibility of using a non-invasive eye scan to screen for early signs of Alzheimer's disease.

In a study led by Dr Carol Cheung of the Singapore Eye Research Institute, researchers used advanced retinal scanning to test the thickness of the retinal ganglion cell layer, which is linked to the brain.

"The eyes are like a window to the brain, certain structures are connected," explained Associate Professor Christopher Chen, Director of the Memory Aging and Cognition Centre at the National University Health System.

Compared to the average person, they found that this layer was 6 per cent thinner in patients with Alzheimer's. The same layer was also 5 per cent thinner in those with mild cognitive impairment.

These results came from from tests done with 100 Alzheimer's patients, as well as 41 people with mild cognitive impairment and 123 people without any neurodegenerative conditions.

Currently, doctors look out for early warning signs of Alzheimer's disease by asking a series of questions about a person's social behaviour and forgetfulness. Sometimes, magnetic resonance imaging (MRI) tests are done to assess changes in the brain.

"But if we could have a less invasive method of screening for Alzheimer's, such as an eye scan, it would benefit patients," Prof Chen said.

The advanced retinal scan may cost less than $100 for private and subsidised patients, a fraction of the cost of an MRI.

Prof Chen hopes that the convenient test can eventually become a screening tool to catch Alzheimer's at an earlier stage, so that doctors can start intervention as soon as possible.

At least two more studies are being done to conclude if the eye scan can be a reliable tool for Alzheimer's screening. It may take at least five years to reach a conclusion, Dr Cheung said.