Abstract
Purpose :
Sensitive and specific biomarkers for Parkinson’s disease (PD) presence and severity have been largely elusive. OCT changes have been shown in PD; however, few studies have explored retinal microvascular changes. Neuroimaging combined with OCTA has the potential to uncover correlates of disease and identify early biomarkers to facilitate disease-modifying drug discovery.
Methods :
This is a prospective study, in collaboration with Parkinson’s disease experts in the Vanderbilt Department of Neurology, of patients with Parkinson’s and age-matched healthy control designation undergoing [18F]-fallypride imaging of striatal and extrastrial D2/3 receptors. Patients from that study, without preexisting ocular disorders, prior ocular surgery, or severe motor impairment/dyskinesia confounding scan acquisition are recruited for a dilated fundus exam & OCTA. 7 PD patients (14 eyes) received OCTA (RTVue Avanti, 6 x 6 mm, with auto segmentation) to date. FAZ density from the preliminary cohort was compared with age-matched normative values in the literature.
Results :
For PD, the average whole image vessel density was 49.16% (+/- 3.37), foveal vessel density was 38.51% (+/- 5.30), and parafovea vessel density was 51.77% (+/- 3.63). On average, fovea thickness was 284.07mm (+/- 36.75) and parafovea thickness was 326.86mm (+/- 13.27). The FAZ area was .20 mm2 (+/- .06) which was statistically significantly less (p=.0056) than the lower bound estimated average FAZ of .28 mm2 +/- .1 from normative studies of healthy controls (135 eyes, with a similar age rage, using the RTVue). Compared to an aged, healthy, non-dementia cohort, using an identical machine, frame size, and auto-segmentation protocol, with a FAZ of .33 mm2 +/- .08, the average FAZ was statistically significantly smaller (p=.0005), while whole image, foveal, and parafovea vessel densities showed no statistically significant differences. However, other cohorts using similar methodology report healthy non-dementia control FAZ area of .21 mm2+/- .07.
Conclusions :
This pilot study explores retinal microangiographic correlates of Parkinson’s disease. Early OCTA findings suggest PD patients have smaller FAZ area than healthy controls which corroborates prior studies using fluorescein angiography. Given the emerging body of literature, further research of retinal and choroidal microvascular changes in PD is warranted.
This is a 2020 ARVO Annual Meeting abstract.