Retinal microvasculature and 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 consecutively and prospectively recruited enrolled in the current study. En face angiograms of the superficial vascular complex (SVC), deep vascular complex (DVC), superficial vascular plexus (SVP), intermediate capillary plexus (ICP), and deep capillary plexus (DCP) were generated by automatic segmentation using swept-source optical coherence tomography angiography (SS-OCTA) to assess the retinal microvascular perfusion. The cerebral blood flow perfusion on bilateral middle cerebral artery territories measured at the basal ganglia level was assessed by brain computed tomography perfusion (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 on the contralateral side to that on the ipsilateral side. Results In the final analysis, 31 patients were included, of whom 11 patients had a moderate ICA stenosis (50-69%) and 20 with a severe ICA stenosis(>= 70%). 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 SVC with rCBV(B = 0.45, p = 0.03), rCBF(B = 0.26, p = 0.02) and rPS(B = 0.45, p < 0.001) after adjustment for age, sex and vascular risk factors. Similar correlations were also found between microvasculature in SVP and cerebral perfusion changes. There were no any significant associations of microvascular perfusion in both DVC and DCP with CTP parameters(all p > 0.05). Conclusions Retinal perfusion changes in superficial vascular layer (SVC and SVP) were correlated with brain hemodynamic compromise in patients with unilateral moderate or severe ICA stenosis(>= 50%). Given the limited size of our study, future studies with larger sample size are needed to confirm our findings.