A new study from Korea found the loss of brain cells responsible for the production of dopamine, which helps control movement, is mirrored by retinal cell loss in patients with Parkinson’s disease (PD).1

“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,” said study author Jee-Young Lee, MD, PhD, of the Seoul Metropolitan Government–Seoul National University Boramae Medical Center in South Korea, in a press release from the American Academy of Neurology.2

The study, published online in Neurology, included 49 patients diagnosed with PD for at least two years who had yet to start medical therapy, and 54 controls. A complete eye exam that included macular optical coherence tomography, microperimetry, dopamine transporter positron emission tomography and magnetic resonance imaging in the PD patients revealed retinal thinning in the temporal and inferior 2.22mm sectors, the study said.1

 They also found an association between retinal thinning and dopaminergic loss in the left substantia nigra.1

 When the researchers measured disease disability on a scale of one to five, they found those with the thinnest retina (less than 30μm) had a score barely over two, while those with a retinal thickness of approximately 47μm scored an average of 1.5.

If larger studies that scan more of the retina and follow patients longer confirm these findings, “retina scans may not only allow earlier treatment of Parkinson’s disease but more precise monitoring of treatments that could slow progression of the disease as well,” Dr. Lee said.2

1. Ahn J, Lee JY, Kim TW, et al. Retinal thinning associates with nigral dopaminergic loss in de novo Parkinson disease. Neurology. August 15, 2018. [Epub ahead of print].

2. Study: the eyes may have it, an early sign of Parkinson’s disease. American Academy of Neurology. August 15, 2018.