Critter Corner: Can an Eye Exam Predict Alzheimer’s?


Dear Ernie and Janette,

I read somewhere that a simple eye exam can predict whether or not someone will get Alzheimer’s. Is this true?

Thanks!

Cici Cleary

Dear Cici,

You are correct. It may be possible to accurately screen patients for Alzheimer’s using a simple eye exam in the not-so-distant future, according to new research. Using technology similar to what is currently found in ophthalmologists’ offices, researchers have detected evidence indicating Alzheimer’s in older patients who had no other symptoms.

“This technique has great potential to become a screening tool that helps decide who should undergo more expensive and invasive testing for Alzheimer’s disease prior to the appearance of clinical symptoms,” says Bliss E. O’Bryhim, a resident physician in the ophthalmology & visual sciences department at Washington University in St. Louis. “Our hope is to use this technique to understand who is accumulating abnormal proteins in the brain that may lead them to develop Alzheimer’s.”

Study Performed Helps Prove Findings

In a new study, which appears in JAMA Ophthalmology, researchers used a noninvasive technique to examine the retinas in eyes of 30 participants with an average age in the mid-70s, none of whom exhibited symptoms of Alzheimer’s disease. Based on the eye scans, about half of those in the study had elevated levels of the Alzheimer’s proteins amyloid or tau, suggesting that although they didn’t have symptoms, they likely would develop the disease. In the other subjects, scans and fluid analyses were normal.

Scientists found the following in participants who were more likely to develop Alzheimer’s:

Thinning retina: Thinning of the retinal tissue and a dearth of teeny blood vessels in its center was detected in people who had tested positive for the Alzheimer’s proteins. For additional proof, in previous studies, researchers reported that the eyes of patients who had died from Alzheimer’s disease showed signs of thinning in the center of the retina and degradation of the optic nerve.

Blood flow: According to researchers, “(a)ll of us have a small area devoid of blood vessels in the center of our retinas that is responsible for our most precise vision. We found that this zone lacking blood vessels was significantly enlarged in people with preclinical Alzheimer’s disease.”

The eye test researchers used in the study shines light into the eye, allowing a doctor to measure retinal thickness, as well as the thickness of fibers in the optic nerve. A form of that test often is available in ophthalmologist’s offices, but not yet being used for this purpose.

Right now, more studies in patients are needed to replicate the findings. Scientists note that if changes detected with this eye test can serve as markers for Alzheimer’s risk, it may be possible one day to screen people as young as their 40s or 50s to see whether they are at risk for the disease.

Hop this is helpful,

Ernie and Jannette

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