The eyes may be a window to the brain for people with early Parkinson’s disease. People with the disease gradually lose brain cells that produce dopamine, a substance that helps control movement. Now, a new study by South Korean researchers 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 involved 49 people with an average age of 69 who were diagnosed with Parkinson’s disease an average of two years earlier but who had not yet started medication. They were compared to 54 people without the disease who were matched for age. The researchers found retina thinning (most notably in the two inner layers of the five layers of the retina) in those with Parkinson’s disease. In addition, the thinning of the retina corresponded with the loss of brain cells that produce dopamine and also with the severity of disease. The findings have been published in Neurology .
