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Cognitive Function and The Eyes Part Two

Posted by Ilena Di Toro | Posted on November 29, 2022

Part One dealt with how memory works in tandem with vision. Since eyes are part of the body, they can provide indications of diseases such as diabetes and high blood pressure. Do the eyes provide clues about cognitive health? According to researchers at the American Optometric Association, the answer is yes.

The understanding of the connection between eye health and overall health has grown over the past 30 years. This is due to advances in optical coherence tomography (OCT) technology. Researchers are studying retinal imaging obtained from OCT scans to see if there are ways to obtain an early diagnosis of age-related brain disorders, such as Alzheimer’s.

The retina is the focus of this research since it is an extension of the brain and it holds clues for neurological function. In fact, the eyes are the first place to show signs of a neurological disorder, such as multiple sclerosis and Parkinson’s disease. One of the advantages of studying the retina is that it is easily accessible through noninvasive imaging, such as the OCT.

A paper written in 2020 by Michael R. Dueñas, OD the American Optometric Association chief public health officer, and Peter J. Snyder, Ph.D, vice president of research at The University of Rhode Island and a leading researcher in the field of retinal imaging and Alzheimer’s Disease found that the disease’s biomarkers can be located in the retina with the use of OCT imaging. Once you combine this with the optometry’s accessibility and its track record in providing medical eye care for those over the age of 60, optometry can be the means in which early diagnosis of Alzheimer’s can take place.

That’s a big deal since over 46 million people in the U.S. have preclinical Alzheimer’s. In fact, amyloid beta plaques and neurofibrillary tau tangles have been found in the retinas of persons with Alzheimer’s. Snyder and other researchers theorized that this is a part of a cascade of structural changes in the retina. Another change is a thinning retinal nerve fiber layer, yet it isn’t known which quadrant is involved and what stage of disease progression that the change happens most quickly.

The thing is, how specific are the retinal biomarkers, as opposed to being sensitive. According to Synder, when using a screening marker for a large population, it is better to be sensitive than specific. Being that there are many diseases that affect the retina in similar ways to Alzheimer’s, it is conceivable to one day combine retinal screening markers with blood-based markers, as a cost-effective way to screen for Alzheimer’s.

While it seems a bit odd for persons not in the medical field that optometrist would one day be able screen for Alzheimer’s Disease, Snyder and Duenas make the case that optometrists are well-positions to do these screenings. Optometrists are already examining the over 60 population and the field has established a good track record with diabetes and cardiac screenings, so the next disease optometrists can screen for most likely is Alzheimer’s.

Once again research shows that there is more to vision and the brain than what meets the eye.


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