Retinal health may help detect early symptoms of Alzheimer's disease

Alzheimer Disease

Alzheimer Disease

A quick eye exam might one day allow eye doctors to check up on both your eyeglasses prescription and your brain health.

"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 Sharon Fekrat, lead author of the study.

Scientists found the retina was thinner in people with Alzheimer's and they had also lost more small blood vessels at the back of the eye, compared to healthy people and those with mild cognitive impairment, a forerunner to dementia. In cases of Alzheimer's disease, these microscopic vessels are found inside the retina as a dense web.

Diagnosing the condition at present involves a brain scan, a spinal tap to analyse cerebrospinal fluid or, more frequently, a doctor assessing symptoms. It is possible these changes in retina blood vessel density are mirroring what is happening with brain blood vessels. The differences in density were statistically significant after researchers controlled for factors including age, sex, and level of education, said Duke ophthalmologist and retinal surgeon Sharon Fekrat, M.D., the study's senior author.

For their study, researchers used OCTA to compare the retinas in 70 eyes of 39 Alzheimer's patients with 72 eyes of 37 people with mild cognitive impairment, as well as 254 eyes of 133 cognitively healthy people.

Duke Eye Center recently recruited and studied the retinas of over 200 individuals to see if there were any differences between those with Alzheimer's and those without. OCTA machines use light waves that reveal blood flow in every layer of the retina.

Because the retina is an extension of the brain and shares many similarities with the brain, researchers believe that the deterioration in the retina may mirror the changes going on in the blood vessels in the brain, thereby offering a window into the disease process. Such techniques to study the brain are invasive and costly.

In addition to Fekrat and Grewal, study authors include Stephen P. Yoon, Atalie C. Thompson, Bryce W. Polascik, Cynthia Dunn and James R. Burke. The primary aim for researchers was to spot retinal degeneration that may be particularly linked to Alzheimer's disease.