Accumulating evidence shows that the eyes are involved in the development of Parkinson’s disease, since PD patients have damaged retinal dopamine neurons. Recent discoveries show a link between these neurons and the substantia nigra, and that damage to one area causes corresponding damage to the other.
In a series of experiments, investigators placed into animals’ eyes several toxins known to cause Parkinson’s in amounts too small to diffuse into the brain. They found that the animals developed PD.
“For the first time we discovered a pathway that can cause the disease. This opens the door to find better tools to treat Parkinson’s,” said Dan Adams, chief science officer at PhotoPharmics, in a recent news release.
The investigators used the eyes as a treatment pathway to deliver minute amounts of dopamine and other medications, which resulted in a rapid symptom recovery in the animals.
Light activates retinal dopamine and suppresses melatonin. Exposing the animals to experimental light conditions produced a two-fold recovery compared to dopamine or melatonin antagonists alone.
Parkinson’s patients are photosensitive leading researchers to experiment low-intensity phototherapy for patients with PD. According to PhotoParmics, preliminary studies have shown improvement in symptoms with certain wavelengths.
The new trial currently underway in the U.S. and Europe is a randomized double-blind, parallel study, with a duration of 7 ½ months per patient. This includes a two-week baseline assessment period, six month treatment period, and one-month follow-up. The trial should be concluded by September 2016.