Research suggests that it may be possible to notice signs of dementia, years before symptoms occur, through an eye test that an optician could carry out.

Scientists believe that detecting the disease early could be crucial in the search for treatments as they are more likely to be effective before it has developed.

Researchers found abnormalities in night vision in mice linked to retinal function. Specifically, light sensitive cells called rods that enable them to see in the dark were faster at responding to flashes of dim light.

They believe that their findings show diseases of the central nervous system may show up in changes in the retina before the brain.

They said the findings suggest an eye examination could be used as a “non invasive screening tool” for brain diseases, including Alzheimer’s.