New research shows an eye scan can detect the early signs of Alzheimer’s disease

Researchers from the Duke Eye Center in North Carolina have found a novel method of detecting signs of Alzheimer’s disease using optical coherence tomography angiography (OCT-A). The team found that small blood vessels in the back of the eye are altered in people diagnosed with the degenerative disease.“We know that there are changes that occur in the brain in the small blood vessels in people with Alzheimer’s disease,” study lead author Dr Dilraj Grewal told Physics World.“Because the retina is an extension of the brain, we wanted to investigate whether these changes could be detected in the retina using a new technology that is less invasive and easy to obtain.”The study was published in Ophthalmology Retina, a journal of the American Acady of Ophthalmology, and posited that the method could also distinguish between people with full-blown Alzheimer’s and those affected with only a mild cognitive impairment.The non-invasive OCT-A enables clinicians to visualise blood vessels located at the back of the eye, which are thinner than the width of human hair, and reveal changes in a matter of seconds.The researchers believe that since the retina shares many similarities with the brain, any damage caused by deterioration in retinal microvasculature could mirror changes in the brain.“We’re measuring blood vessels that can’t be seen during a regular eye exam and we’re doing that with relatively new non-invasive technology that takes high-resolution images of very small blood vessels within the retina in just a few minutes,” study senior author Dr Sharon Fekrat said.The team used OCTA images of 39 patients diagnosed with Alzheimer’s, 37 people with mild cognitive impairment – considered a precursor to Alzheimer’s disease – and 133 cognitively healthy people.In the healthy group, the researchers discovered that microscopic blood vessels form a dense web at the back of the eye inside the retina was less dense among those with Alzheimer’s.The researchers also found that a specific layer of the retina was thinner in the Alzheimer’s group than in people with mild cognitive impairment and the control group. The differences in density were significant even after factors including sex and age were accounted for.