Neurologists may eventually be able to use a simple eye scan to detect Parkinson’s disease in its earliest stages
People with Parkinson’s disease gradually lose brain cells that produce dopamine, a substance that helps control movement. A new study has found that the thinning of the retina, the lining of nerve cells in the back of the eye, is linked to the loss of such brain cells. The study was published in the online issue of Neurology®, the medical journal of the American Academy of Neurology.
“Our study is the first to show a link between the thinning of the retina and a known sign of the progression of the disease — the loss of brain cells that produce dopamine,” said study author Jee-Young Lee, MD, PhD, of the Seoul Metropolitan Government – Seoul National University Boramae Medical Center in South Korea.
“We also found the thinner the retina, the greater the severity of disease. These discoveries may mean that neurologists may eventually be able to use a simple eye scan to detect Parkinson’s disease in its earliest stages, before problems with movement begin,” he added.
A 2016 article in the Annals of the Indian Academy of Neurology noted the lack of population level data about the incidence of Parkinson’d Disease (PD) in India. “There are very few population-based studies determining the exact incidence and prevalence of PD in India. In a door-to-door survey done in Bangalore district in South Karnataka in India in 2004, the prevalence rate of Parkinsonism was found to be 33 per 100,000 (crude prevalence) and 76 per 100,000 (age adjusted). Rural population had a higher prevalence compared to the urban population (41 vs 14). But it was less compared to other highly prevalent neurological disorders such as headache, epilepsy, stroke, and mental retardation. From a survey in Kolkata in 2006, the prevalence of Parkinsonism was found to be 45.82 per 100,000.”
Researchers found retina thinning, most notably in the two inner layers of the five layers of the retina
The article added: “In the state of Kashmir, the prevalence was 14.1 per 100,000, while the age adjusted prevalence was 134 per 100,000. A survey, done in Parsi community in Mumbai, a small stable community, showed a prevalence of 192 per 100,000, which was higher compared to rest of the population. In a surveillance in old age homes in a Bangalore, there was very high prevalence of 17.6% (109/612 residents) of Parkinsonism. This may be due to unawareness of this disorder among the general population who do not avail the medical facilities at the appropriate time.”
In the present study researchers found retina thinning, most notably in the two inner layers of the five layers of the retina, in those with Parkinson’s disease. The inner most layer of the retina in one section of the eye, for those with Parkinson’s disease had an average thickness of 35 micrometers (μm) compared to an average thickness of 37 μm for those without the disease.
The thinning of the retina also correlated with the loss of brain cells that produce dopamine and it also corresponded with the severity of the disease. Limitations of the study were that the retina scans focused only on a limited area of the retina and the study did not follow participants over a long period of time.