Effects of Obstructive Carotid Artery Disease on Ocular Circulation and the Safety of Carotid Artery Stenting

Abstract

Background: The aims of this study were to examine the ophthalmic artery flow changes in patients with obstructive carotid artery disease, evaluate the orbital blood flow changes after carotid artery stenting and assess the safety of carotid stenting procedure by using transorbital colour and spectral Doppler sonography. Methods: Thirty-one consecutive patients scheduled for carotid stenting with severe internal carotid artery stenosis (>60%; the study group) and 30 control subjects were included. Ophthalmic artery (OA) Doppler sonography was performed in the control group and study group before and after stenting. Peak systolic velocity (PSV), end-diastolic velocity (EDV), pulsatility index (PI), and resistive index (RI) and systolic/diastolic ratio (S/D) in the ophthalmic artery were recorded. Statistical comparisons were made between controls and study group before stenting and before and after stenting in the study group. Results: Comparison between control and study group before stenting revealed a statistically significant decrease in OA PSV (51.5 +/- 14.5 vs. 39.7 +/- 19cm/sec, p= 0.008) and EDV (15.2 +/- 4.5 vs. 11.3 +/- 5.7cm/sec, p=0.004) in the study group. Differences in PI (1.3 +/- 0.14 vs. 1.36 +/- 0.4, p=0.47), RI (0.7 +/- 0.04 vs. 0.75 +/- 0.21, p=0.19), and S/D (3.5 +/- 0.6 vs. 3.6 +/- 1, p= 0.5) ratio were not statistically significant between groups. Peak systolic velocity (39.7 +/- 18.9 vs. 51.3 +/- 22.2cm/sec, p <0.001), RI (0.75 +/- 0.21 vs. 0.81 +/- 0.13, p=0.16) and S/D ratio (3.6 +/- 1 vs. 4.6 +/- 1.5, p= 0.001) were found to be significantly increased in the study group after stenting compared to baseline. There were no statistically significant differences in EDV and RI EDV(11.3 +/- 5.7 vs. 11.7 +/- 5.7cm/sec, p=0.66), PI (1.36 +/- 0.4 vs. 1.6 +/- 0.6, p =0.047) after stenting. Conclusions: Ophthalmic artery flow parameters were significantly lower in patients with severe carotid artery stenosis compared to control, indicating compromised ocular blood flow in severe carotid stenosis. Flow indicators significantly improved after stent implantation suggesting the importance of revascularisation in restoring ocular blood flow and safety of carotid stenting.