This new eye test could detect Parkinson's disease before symptoms develop.
Developed at the University College London Institute of Ophthalmology it looks for changes in patients' retinas before brain alteration occurs.
Researchers induced Parkinson's in rats by injecting them with a chemical called rotenone.
Having observed retinal changes, they treated the rodents with a new version of anti-diabetic drug Rosiglitazone.
SOUNDBITE (English) UCL CONSULTANT OPTHALMOLOGIST, DR EDUARDO NORMANDO, SAYING:
"The preliminary results were that we were able to see evidence of Parkinson's in the retina well in advance compared to the Parkinsonian events in the brain. Furthermore, by injecting the Rosiglitazone in these rats we were able to see a rescue effect of Rosiglitazone in this model, first in the eye and then in the brain."
Human clinical trials will begin soon.
Earlier diagnosis could have a major impact on future patient outcomes.
SOUNDBITE (English) UCL PROFESSOR OF GLAUCOMA AND RETINAL NEURODEGENERATION, FRANCESCA CORDEIRO , SAYING:
"If you've seen the effects in the retina well before you see those effects in the brain then actually you could shorten the length of clinical trials and you could use this as a very good marker of treatment success. But in the long run what we think is that it could be a way of trying to see if patients are ever going to get Parkinson's disease."
The team says patients predicted to get the disease could have their subsequent treatment monitored by the test.
Leading support and research charity Parkinson's UK welcomed the findings.
SOUNDBITE (English) DIRECTOR OF RESEARCH AT PARKINSON'S UK, DR ARTHUR ROACH, SAYING:
"This is one of many examples of work into new biomarkers for Parkinson's. So it's a very active field. I think any one of these could really transform the field, and this is a very good candidate for bringing us a real advance."
The degenerative condition affects 1 in 500 people, causing muscle stiffness, slowness of movement, tremors and a reduced quality of life.
Symptoms typically become apparent once more than 70 percent of the brain's dopamine-producing cells have been destroyed.