Ocular Ischemic Syndrome and the Role of Carotid Artery Revascularization

BACKGROUND

Ocular ischemic syndrome (OIS) is a rare presentation of atherosclerotic carotid artery stenosis that can result in permanent visual loss. This severely disabling syndrome remains under diagnosed and undertreated due to lack of awareness; especially since it requires expedited multidisciplinary care. The relevance of early diagnosis and treatment is increasing due to an increasing prevalence of cerebrovascular disease.

METHODS

The long-term visual and cerebrovascular outcomes following intervention for nonarteritic OIS, remain poorly described and were the objective of this concise review. We conducted a PubMed search to include all English language publications (cohort studies and case reports) between 2002 and 2023.

RESULTS

A total of 33 studies (479 patients) report the outcomes of treatment of OIS with carotid endarterectomy (CEA, 304 patients, 19 studies), and carotid artery stenting (CAS, 175 patients, 14 studies). Visual outcomes were improved or did not worsen in 447 patients (93.3%). No periprocedural stroke was reported. Worsening visual symptoms were rare (35 patients, 7.3%); they occurred in the immediate postoperative period secondary to ocular hypoperfusion (3 patients) and in the late postoperative period due to progression of systemic atherosclerotic disease. Symptomatic recurrence due to recurrent stenosis after CEA was reported in 1 patient (0.21%); this was managed successfully with CAS. None of these studies report the results of transcarotid artery revascularization, the long-term operative outcome or stroke rate.

CONCLUSIONS

OIS remains to be an underdiagnosed condition. Early diagnosis and prompt treatment are crucial in reversal or stabilization of OIS symptoms. An expedited multidisciplinary approach between vascular surgery and ophthalmology services is necessary to facilitate timely treatment and optimize outcome. If diagnosed early, both CEA and CAS have been associated with visual improvement and prevention of progressive visual loss.

Changes in retinal vascular density measured by optical coherence tomography angiography in patients with carotid artery stenosis after carotid artery stenting and angioplasty

PURPOSE

The aim of this study was to compare the effect of carotid artery stenting and angioplasty (CASA) on retinal vascular density (VD) in patients with severe carotid stenosis with a healthy control group and to evaluate using optical coherence tomography angiography (OCTA).

METHODS

For this prospective study, eyes on the operated side constituted the ipsilateral eye group, and the other eye constituted the contralateral eye group. 40 eyes of 40 patients with ipsilateral eye of carotisid artery stenosis (CAS), 34 eyes on contralateral side, and 30 healthy eyes (control group) were included in this study. We performed quantitative OCTA analyses of retinal VD changes, before and after CASA. The main outcome measures were the quantitative changes of VD of superficial capillary plexus (SCP) and deep capillary plexus (DCP).

RESULTS

We evaluated the VD of ipsilateral eyes and contralateral eyes separately before and after the procedure. All patients did not have visual symptoms. There was no significant difference in the VD of SCP in all groups before the procedure. No significant change was observed in all groups when the VD of the SCP was compared before and after the procedure. The VD of the DCP in the ipsilateral and contralateral group improved significantly after CASA.

CONCLUSION

OCTA could noninvasively detect retinal VD improvements after CASA in CAS patients. Quantitative changes in VD evaluated using OCTA are thought to be early indicators in the diagnosis of CAS and in the follow-up of treatment success.

Impaired cerebrovascular reactivity correlates with reduced retinal vessel density in patients with carotid artery stenosis: Cross-sectional, single center study

BACKGROUND

The cerebral and retinal circulation systems are developmentally, anatomically, and physiologically interconnected. Thus, we hypothesized that hypoperfusion due to atherosclerotic stenosis of the internal carotid artery (ICA) can result in disturbances of both cerebral and retinal microcirculations. We aimed to characterize parameters indicating cerebrovascular reactivity (CVR) and retinal microvascular density in patients with ICA stenosis, and assess if there is correlation between them.

METHODS

In this cross-sectional study the middle cerebral artery (MCA) blood flow velocity was measured by transcranial Doppler (TCD) and, simultaneously, continuous non-invasive arterial blood pressure measurement was performed on the radial artery by applanation tonometry. CVR was assessed based on the response to the common carotid artery compression (CCC) test. The transient hyperemic response ratio (THRR) and cerebral arterial resistance transient hyperemic response ratio (CAR-THRR) were calculated. Optical coherence tomography angiography (OCTA) was used to determine vessel density (VD) on the papilla whole image for all (VDP-WIall) and for small vessels (VDP-WIsmall). The same was done in the peripapillary region: all (VDPPall), and small (VDPPsmall) vessels. The VD of superficial (VDMspf) and deep (VDMdeep) macula was also determined. Significance was accepted when p<0.05.

RESULTS

Twenty-four ICA stenotic patients were evaluated. Both CVR and retinal VD were characterized. There was a significant, negative correlation between CAR-THRR (median = -0.40) and VDPPsmall vessels (median = 52%), as well as between VDPPall vessels (median = 58%), and similar correlation between CAR-THRR and VDP-WIsmall (median = 49.5%) and between VDP-WIall (median = 55%).

CONCLUSION

The significant correlation between impaired cerebrovascular reactivity and retinal vessel density in patients with ICA stenosis suggests a common mechanism of action. We propose that the combined use of these diagnostic tools (TCD and OCTA) helps to better identify patients with increased ischemic or other cerebrovascular risks.

Structural Analysis of the Retina and Choroid before and after Carotid Artery Surgery

Purpose: To evaluate retinal and choroidal changes in patients with internal carotid artery stenosis who had undergone carotid artery stenting or endarterectomy.Methods: The study included 43 patients with internal carotid artery (ICA) stenosis that required stenting or endarterectomy and 40 healthy controls. Patients were divided into two groups according to the degree of stenosis evaluated by magnetic resonance angiography. Group 1 consisted of patients having ICA stenosis of 50 to 70%, and Group 2 has more than 70%. Enhanced depth imaging optical coherence tomography (EDI-OCT) was used to measure the retinal thickness (RT) and choroidal thickness (CT) in all subjects before surgery and at 1, 3, and 6 months after surgery.Results: Subfoveal and parafoveal CT were significantly lower in patients with ICA stenosis than the control group (p < .05, respectively). Patients with 50-70% stenosis had a significant increase in the CT at 1, 3, and 6 months after ICA stenting or endarterectomy (p < .05). Patients with >%70 stenosis did not have a significant increase in the CT at any time after ICA stenting or endarterectomy. Retinal thickness was not statistically different between the patients with ICA stenosis and the control subjects, and RT showed no significant change in patients with ICA stenosis before and after the surgery.Conclusion: Choroidal thickness was significantly thinner in patients with internal carotid artery stenosis. ICA stenting provided a recovery in the choroidal thickness in patients with moderate to advanced stenosis.

Changes in retinal flow density measured by optical coherence tomography angiography in patients with carotid artery stenosis after carotid endarterectomy

The aim of the study presented here was to evaluate retinal and optic nerve head (ONH) perfusion in patients with severe asymptomatic carotid artery stenosis (CAS) compared with healthy controls and to analyze the impact of carotid endarterectomy using optical coherence tomography angiography (OCT-A). 25 eyes of 25 patients with CAS (study group) and 25 eyes of 25 healthy controls (control group) were prospectively included in this study. OCT-A was performed using RTVue XR Avanti (Optovue, Inc, Fremont, California, USA). The flow density data in the superficial and deep retinal OCT-angiogram of the macula and in the radial peripapillary capillary network (RPC) of the ONH were extracted and analyzed. The flow density in the superficial retinal OCT angiogram of the macula and in the ONH were significantly lower in the study group compared with the control group (macula: p = 0.003) (ONH: p = 0.013). The flow density in the ONH improved significantly after carotid endarterectomy (p = 0.004). A reduced flow density was observed in patients with CAS when compared with healthy controls. The flow density also improved after carotid endarterectomy. Quantitative changes in the microvascular density, as measured using OCT-A, could well be useful in the diagnosis of CAS and the evaluation of therapy success.

Changes in Ocular Subfoveal Choroidal Thickness After Carotid Endarterectomy Using Enhanced Depth Imaging Optical Coherence Tomography: A Pilot Study

The influence of both severe chronic carotid stenosis and carotid endarterectomy (CEA) on ocular tissue has been poorly evaluated. The goal of this study was to measure subfoveal choroidal thickness (SFCT), before and after CEA, in patients with severe carotid stenosis. Consecutive patients (n = 36) with severe carotid stenosis were prospectively included. Patients (n = 19) were followed up at 1 and 3 months after CEA. The SFCT was measured bilaterally using enhanced depth imaging optical coherence tomography (EDI-OCT). Preoperatively, the median SFCT of the ipsilateral eye did not differ significantly from the contralateral eye (223 vs 236 µm; P = .75). In the ipsilateral eye, the mean SFCT was significantly higher at 1 month postsurgery and the effect was maintained at 3 months (226.3 ± 17.1 at 3 months vs 210.8 ± 16.5 µm at baseline; P < .001). For the contralateral eye, the increase in SFCT reached statistical significance at 3 months (220.1 ± 11.3 at 3 months vs 214.8 ± 11.5 µm at baseline; P = .04). The mean SFCT significantly increased bilaterally after CEA, with a more noticeable effect in the ipsilateral eye. Further studies are required to determine whether EDI-OCT could be useful as a potential marker of ophthalmologic outcomes.