Can an eye scan predict Parkinson’s disease?

Evan Walker
Evan Walker TheMediTary.Com |
A male patient undergoing an optical coherence tomography (OCT) scanShare on Pinterest
The eyes might hold the key to spotting signs of Parkinson’s. AzmanL/Getty Images
  • Parkinson’s disease can affect the eyes, causing vision changes, dry eye, and reading difficulties.
  • Researchers from Moorfields Eye Hospital and UCL Institute of Ophthalmology have found specific markers in the eye indicating the presence of Parkinson’s disease.
  • Scientists say these markers can be found on average seven years before a person receives an official diagnosis.

More than 10 million people around the world have Parkinson’s disease — a neurological disease that affects a person’s ability to move.

Researchers are still unclear as to why a person may get Parkinson’s disease, but there are some indications that disturbances of the gut microbiome might play a role. And because early symptoms of Parkinson’s disease develop gradually, they can sometimes be hard to spot.

One area of the body that can show signs of Parkinson’s disease is the eyes. People with Parkinson’s disease may experience changes to their vision, dry eye, and/or difficulty reading or keeping their eyes fully open.

Now, researchers from Moorfields Eye Hospital and UCL Institute of Ophthalmology have found specific eye markers indicating Parkinson’s disease.

Scientists say these markers can be found on average seven years before a person receives an official diagnosis.

This study was recently published in the journal Neurology, the medical journal of the American Academy of Neurology.

According to Dr. Wagner, the researchers decided to look for markers of Parkinson’s disease in eye scans because the disease is characterized by the loss of cells using the neurotransmitter dopamine.

“The eye represents an accessible window into the brain and, importantly, also houses cells using the chemical dopamine,” he explained to Medical News Today.

Previous work has shown that features of dopamine cell loss can be found in histological studies of retinal tissue in people with Parkinson’s disease; however, it has never been consistently observed in in-vivo imaging,” he said.

After reviewing this study, Dr. Daniel Truong, a neurologist and medical director of The Parkinson’s and Movement Disorder Institute at MemorialCare Orange Coast Medical Center, told Medical News Today the idea that we can detect markers of Parkinson’s disease through eye scans up to seven years before clinical presentation is revolutionary.

“Together with other Health">prodromal signs such as Health">loss of the sense of smell, Health">constipation, Health">REM sleep behavior disorder, this early detection could open up new avenues for early interventions, allowing us to potentially alter the course of the disease or at least manage symptoms more effectively,” he continued.

“Interestingly, the method of detection is not invasive. OCT scans of the retina are quick, highly detailed, and noninvasive, providing valuable insights not just about eye health but broader health conditions, too,” he said.

However, Dr. Truong did state he had a few reservations about this study.

“First and foremost, while these findings are promising, it’s essential to understand how they will translate to real-world clinical settings,” he explained.

“The question would be the cost-effectiveness, accessibility, and the psychological aspect of prediction on healthy patients is also an issue. The study itself is not yet ready to predict if an individual will develop Parkinson’s definitively,” he said.

Medical News Today also spoke with Dr. Howard R. Krauss, a surgical neuro-ophthalmologist and director of Pacific Neuroscience Institute’s Eye, Ear & Skull Base Center at Providence Saint John’s Health Center in Santa Monica, California, who was not involved in the study. He also voiced concerns about the findings.

“Whenever a paper is published, the media picks it up as a breakthrough. The public picks it up as an indication that they can pick up their telephone, call their ophthalmologist, have an OCT done, and learn whether or not they’ll develop Parkinson’s disease, and that’s clearly not the case. An OCT will not tell you if you have, may have, or will have Parkinson’s disease,” he explained.

Dr. Krauss also said it’s important to note that other conditions can cause thinning of the ganglion cell layer and other retina layers that are not specific to Parkinson’s disease.

“Glaucoma, macular degeneration, retinal vascular disease, and a whole host of other things can cause thinning of the ganglion cell layer. In addition to, which was not touched on in this paper, even nearsightedness causes thinning of the ganglion cell layer, so it’s not a specific finding,” he pointed out.

Dr. Krauss said what’s more valuable is finding ophthalmic signs of Parkinson’s disease during a clinical examination.

“For example, patients with Parkinson’s disease have a higher incidence of dry eye, in part because they have a reduced blink rate,” he detailed.

“Patients with Parkinson’s disease have a higher incidence of difficulties with reading because even their eye movements are affected by Parkinson’s disease, and some will present with double vision. So careful clinical examination by an ophthalmologist or neuro-ophthalmologist can find early findings consistent with Parkinson’s disease,” he said.

“In my own practice, over the decades, I have not infrequently been the first practitioner to suggest to a patient that they may have Parkinson’s disease based on findings in their eye examination. So if nothing else, this [study] serves as a reminder that one should have [r]egular eye examinations because there is indeed a lot about the eye and about the examination findings of the eye that tell us about a variety of systemic diseases, including Parkinson’s disease.”
— Dr. Howard R. Krauss

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