Looking beyond the brain: Insights into vascular parkinsonism with optical coherence tomography

Vascular Parkinsonism (VP) is characterized by rigidity and bradykinesia predominantly affecting the lower limbs. Optical Coherence tomography (OCT) facilitates the visualization of retina and choroid and may help in delineating differential involvement of retina and choroid in patients with VP. In this study, we report the pattern of changes in the retinal and choroidal layers in patients with VP with the help of spectral domain OCT (SD-OCT).We adopted a case-control design and evaluated 24 patients with VP with complete history, clinical examination, Montreal Cognitive Assessment (MOCA), Unified Parkinson's Disease Rating Scale (UPDRS) motor part in OFF state, and retinal and choroidal imaging with SD-OCT. The peripapillary retinal nerve fiber layer (RNFL) thickness, peripapillary choroidal layer thickness (PPChT), central macular thickness (CMT) and subfoveal choroid thickness (SFChT) were assessed. Twenty-two age and gender-matched healthy control subjects were also recruited.The peripapillary RNFL, in most of the segments and CMT were significantly thinner in patients with VP compared to controls. The subfoveal and peripapillary ChT did not differ significantly between patients and controls.This is the first study that has evaluated the role of OCT in patients with VP and these patients have significant involvement of the retina. In addition to providing pathophysiological insights, OCT parameters may serve as disease biomarkers in VP. This study lays the foundation for carrying out future studies with larger sample sizes and a longitudinal design.