SEOUL — Eyes have been called the windows of the soul. Our eyes can also be windows into our inner workings, providing important health clues. One such clue may be a link between thinning of the retina, the nerve cells at the back of the eye, which may signal the development of Parkinson’s disease.
A recent South Korean study found a correlation between retinal thinning and a decrease in brain cells that produce dopamine, a hormone and neurotransmitter that controls movement. Study author Dr. Jee-Young Lee, of the Seoul Metropolitan Government – Seoul National University Boramae Medical Center, says the research is the first to produce such a link.
“We also found the thinner the retina, the greater the severity of disease,” Lee explains in a statement. “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.”
Researchers compared eye exams and high-resolution eye scans of 49 participants with Parkinson’s disease with 54 participants without the disease. The participants averaged 69 years of age. Study authors also used PET scans to measure the thickness of the brain’s dopamine-producing cells in 28 of the Parkinson’s participants.
The results showed more pronounced retinal thinning in participants with Parkinson’s disease, especially in the two innermost layers of the five retina layers. Retinal thinning was found to be a good indicator of the degree of loss of dopamine-producing brain cells as well as the progression of the disease.
Study authors caution that the study was limited to a one-time snapshot of participants’ current eye and brain health and that the scans performed involved only a small area of the retina.
“Larger studies are needed to confirm our findings and to determine just why retina thinning and the loss of dopamine-producing cells are linked,” says Lee. “If confirmed, 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.”
Study results are published online in Neurology, the medical journal of the American Academy of Neurology.