Macular radial peripapillary capillary: a potential optical coherence tomography angiography biomarker of cognitive impairment in patients with internal carotid artery stenosis

We investigated retinal and choroidal microvascular parameters as potential biomarkers for vascular cognitive impairment in patients with internal carotid artery stenosis (ICAS). We enrolled 123 asymptomatic ICAS patients and categorized them into vascular mild cognitive impairment (VMCI) and vascular dementia (VaD) groups using the Montreal Cognitive Assessment. Optical coherence tomography angiography was used to evaluate vessel densities and perfusion areas in various retinal layers. Magnetic resonance imaging-based neuroimaging biomarkers for cerebral small vessel disease (CSVD) were also assessed. Least absolute shrinkage and selection operator logistic regression identified predictor variables, and receiver operating curve analysis assessed the ability of key parameters to distinguish between VMCI and VaD. Compared with VMCI patients, VaD patients had lower radial peripapillary capillary (RPC) perfusion area, higher CSVD burden score, and larger white matter hyperintensity volume (all p < 0.05). Receiver operating curve analysis revealed that the RPC perfusion area of the affected eye had superior discriminatory power for distinguishing VaD from VMCI compared with both the CSVD burden score ( Z = 1.99, p = 0.047) and white matter hyperintensity ( Z = 1.97, p = 0.049). The optimal cutoff value for the 0–1 mm macular RPC perfusion area was determined as 0.068 mm 2 . The optical coherence tomography angiography-derived RPC perfusion area can effectively differentiate VaD from VMCI, suggesting its potential as a noninvasive diagnostic method to support clinical decision-making for ICAS patients.