Simple eye test could detect Parkinson’s before symptoms show
Scientists at the University College London (UCL) Institute of Ophthalmology in the UK have shown that changes in rats’ retinas can predict Parkinson’s disease before visible symptoms like muscle tremors and stiffness start to occur.
If this same technique proves successful in humans as well, it would offer a cheap and non-invasive way to detect the disease and start treatment. It also only requires instruments that are currently in use by ophthalmologists, which means it could also offer an easier way to monitor how well a treatment is working for a patient.
“This is potentially a revolutionary breakthrough in the early diagnosis and treatment of one of the world’s most debilitating diseases,” said lead researcher Francesca Cordeiro from the University College London. “These tests mean we might be able to intervene much earlier and more effectively treat people with this devastating condition.”
Parkinson’s, which is a progressive neurological condition affecting one in 500 people, can only be diagnosed by a neurologist. But there is no single test or brain scan that can definitely diagnose it. Doctors use a mix of different measures and tests.
This is because the disease starts with small symptoms that are easy to overlook, such as loss of motor control and muscle tremors. Many people don’t get diagnosed until the disease is quite advanced – usually once more than 70% of the brain’s dopamine-producing cells have already been destroyed.
The new technique works by shining light on the back of the eye and looking at how many cells in the retina, known as retinal ganglion cells (RGCs) are going through cell death, as well as detecting signs of swelling in the region.
To figure this out, the team took rats that had been engineered to develop Parkinson’s disease. They detected increased RGC apoptosis and swelling in their eyes days before the animals displayed any physical symptoms. They report that by day 20, they are able to see signs of the disease in the rats’ eyes, and traditional symptoms by day 60.
The researchers also investigated whether treating the condition at this early stage would have any benefits.
They gave the rats a new type of anti-diabetic drug called rosiglitazone, and showed that by treating them early, they were able to effectively reduce the amount of nerve cell damage, compared to animals that didn’t receive early treatment.
“These discoveries have the potential to limit and perhaps eliminate the suffering of thousands of patients if we are able to diagnose early and to treat with this new formulation,” said first author Dr. Eduardo Normando, Consultant Ophthalmologist at Western Eye Hospital and UCL.
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