Structural changes associated with Parkinson's disease (PD) seen via retinal imaging may present a novel biomarker for the disease, according to a cross-sectional study. As Dr. Sharon Fekrat and Dr. Dilraj S. Grewal told Reuters Health by email, "The changes we found in the small blood vessels in the retina and in the choroid may allow us to non-invasively assist in the diagnosis of PD by serving as an easily available screening tool." "While more research is required on this technology," they added, "such a non-invasive and rapid biomarker could also detect disease progression and help evaluate the efficacy of new interventions being investigated in clinical trials. " As reported online in JAMA Ophthalmology, Drs. Fekrat and Grewal of Duke University School of Medicine, Durham, North Carolina and colleagues studied 124 eyes of 69 patients with PD. A further 137 healthy participants (248 eyes) acted as controls. Using optical coherence tomography (OCT) and OCT angiography, each eye of a patient with PD was compared with two eyes of an age- and sex-matched control participant. After exclusions, compared to controls, PD patients had reduced retinal vessel and perfusion densities, increased total choroidal area and choroid luminal area, and reduced choroidal vascularity index. No differences in retinal structure were seen. However, say the investigators, "Subtle changes in the thickness of certain retinal layers and the choroid may be observed in specific individuals with PD and may be outside the limits of resolution of current imaging instrumentation." The researchers further note that "because this is a cross-sectional study of individuals with varying degrees of PD severity, we were not able to identify the prognostic value of retinal imaging in PD." They call for further studies to "clarify whether these imaging findings may be useful as biomarkers for the onset of PD or the rapid deterioration from PD." Commenting by email, Dr. Rajendra S. Apte of Washington University in St. Louis, Missouri, co-author of an accompanying editorial, told Reuters Health, "The retina as a window to neurodegenerative diseases of the brain such as Parkinson's and Alzheimer's disease offers exciting possibilities." "Well-designed prospective studies that identify high risk patients that progress more rapidly, resilient populations, and potentially non-invasive method to gauge treatment response are highly desirable," Dr. Apte said. —David Douglas Source
