An eye exam using non-invasive technology may one day be able to detect Alzheimer’s disease potentially before any cognitive symptoms appear, according to a new study conducted by scientists at the Duke Eye Center, part of Duke University in North Carolia.
The research, published in the journal Ophthalmology Retina, found differences in the retinas of participants with Alzheimer’s disease when compared to healthy people and also to those with mild cognitive impairment, often a precursor to Alzheimer’s disease.
In those with healthy brains, microscopic blood vessels formed a dense web at the back of the eye inside the retina, but in the eyes of those with Alzheimer’s disease, that web was less dense and even sparse in places. The findings suggest that a loss of blood vessels in the retina could be an marker of the debilitating disease.
“We know that there are changes that occur in the brain in the small blood vessels in people with Alzheimer’s disease, and 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,” said Dilraj S. Grewal, M.D., a Duke ophthalmologist and retinal surgeon and a lead author on the study.
The study involved 39 people with Alzheimer’s disease and 133 participants in a control group. The differences in density were statistically significant after researchers controlled for factors including age, sex, and level of education.
The researchers used a noninvasive technology called optical coherence tomography angiography (OCTA). OCTA machines use light waves that reveal blood flow in every layer of the retina. An OCTA scan can even reveal changes in tiny capillaries — most less than half the width of a human hair — before blood vessel changes show up on a brain scan such as an MRI or cerebral angiogram, which highlight only larger blood vessels. Such techniques to study the brain are invasive and costly.
“We’re measuring blood vessels that can’t be seen during a regular eye exam and we’re doing that with relatively new noninvasive technology that takes high-resolution images of very small blood vessels within the retina in just a few minutes,” said Duke ophthalmologist and retinal surgeon Sharon Fekrat, M.D., the study’s senior author.
“It’s possible that these changes in blood vessel density in the retina could mirror what’s going on in the tiny blood vessels in the brain, perhaps before we are able to detect any changes in cognition.”
“Ultimately, the goal would be to use this technology to detect Alzheimer’s early, before symptoms of memory loss are evident, and be able to monitor these changes over time in participants of clinical trials studying new Alzheimer’s treatments,” Fekrat said.
Source: Duke Health