Transocular detection of premotor Parkinson's disease via retinal capillary neurovascular coupling through functional OCT angiography

Early detection of Parkinsons disease (PD) is essential for timely initiating neuroprotective interventions before significant loss of dopaminergic (DAergic) neurons, but faces challenges in accurately and noninvasively detecting subtle neuronal changes in the midbrain. Here, we propose a transocular functional imaging method termed fOCTA-rNVC, which detects premotor PD by measuring alterations in retinal neurovascular coupling (rNVC) at the capillary level using specialized functional OCT angiography (fOCTA). Our findings demonstrate that capillary rNVC is significantly attenuated and delayed due to concurrent retinal dopaminergic degeneration in premotor PD mice. Notably, this PD-related rNVC attenuation can be temporarily reversed in acute levodopa challenge. Utilizing the functional characteristics of capillary rNVC in PD, we achieved an impressive accuracy of [~]100% in detecting premotor PD mice even with only [~]14.1% loss of midbrain DAergic neurons, at which stage prompt treatment offered superior outcomes. In contrast, no significant changes were observed in retinal thickness or vasculature in the premotor PD mice. These findings suggest that fOCTA-rNVC is a promising noninvasive solution for accurately detecting premotor PD and guiding early interventions.