Retinal microvasculature and early cerebral hemodynamics in patients with internal carotid artery stenosis

Purpose: To investigate the relationship between retinal microvasculature and cerebral hemodynamics in patients with internal carotid artery (ICA) stenosis. Methods: : Patients with unilateral moderate or severe ICA stenosis(≥50%) from West China hospital, Sichuan university were enrolled in the current study. The retinal microvasculature was evaluated with the swept-source optical coherence tomography angiography (SS-OCTA). The cerebral blood flow perfusion on bilateral MCA territories measured at the basal ganglia level was assessed by brain CTP. CTP data were postprocessed to generate maps of different perfusion parameters including cerebral blood flow (CBF), cerebral blood volume (CBV), time to peak (TTP), mean transit time (MTT) and permeability surface(PS). Relative perfusion parameters (rPS, rCBF, etc.) were calculated as the ratio of the value in the contralateral side to that in the ipsilateral side. Results: : In the final analysis, 31 patients were included, of whom 11 patients had a moderate ICA stenosis and 20 with a severe ICA stenosis. A total of 55 eyes were analyzed in the study, 27 eyes from the ipsilateral side (ie, side with stenosis) and 28 eyes from the contralateral side. In the patients with ICA stenosis, there was a strong correlation between the retinal microvascular perfusion of superficial vascular complex (SVC) with rCBV(β=0.239, p=0.03 ), rCBF(β=0.472, p=0.02) and rPS(β=0.653, p<0.001) after adjustment for age, sex and vascular risk factors. Similar correlations were also found between microvasculture in superficial vascular plexus (SVP) and cerebral perfusion changes. There were no any significant associations of microvascular perfusion in both deep vascular complex(DVC) and deep capillary plexus(DVP) with CTP parameters (all p>0.05). Conclusions: : Assessing retinal perfusion changes in superficial vascular layer(SVC and SVP)with the SS-OCTA as a proxy for early brain hemodynamic compromise could be a potentially valuable tool for early identification subgroups with a high risk of stroke in patients with ICA stenosis.