Divergent retinal and choroidal vascular alterations associated with retrograde ophthalmic artery flow in chronic carotid total occlusion.

BACKGROUND

Chronic total occlusion (CTO) of the internal carotid artery relies on collateral circulation, often involving retrograde ophthalmic artery (OA) flow. However, the differential vascular patterns of the retina and choroid associated with this hemodynamic alteration remain unclear. We aimed to characterize these alterations using optical coherence tomography (OCT) and OCT angiography (OCTA).

METHODS

This multicenter cross-sectional study enrolled patients with CTO, severe carotid artery stenosis (CAS), and controls. OA flow direction was verified by digital subtraction angiography. Swept-source OCT/OCTA was used to quantify vessel length density (VLD) in the superficial and deep vascular complexes and choroidal parameters (vascular volume [CVV] and vascular index [CVI]).

RESULTS

A total of 216 patients with CTO (419 eyes), 192 with CAS (376 eyes), and 247 controls (467 eyes) were analyzed. Retinal VLD was significantly lower in CTO eyes than in CAS and control eyes (all p < 0.05). In contrast, choroidal parameters were relatively preserved in CTO compared with CAS (both p < 0.05). Within the CTO group, ipsilateral eyes showed reduced retinal VLD compared with contralateral eyes (both p < 0.001), without significant choroidal differences. Among ipsilateral CTO eyes, retrograde OA flow was associated with further even lower retinal VLD but significantly higher CVV and CVI compared with antegrade OA flow (all p < 0.05).

CONCLUSION

Retrograde OA flow in CTO is associated with divergent ocular vascular profiles, characterized by more severe retinal microvascular loss and paradoxical choroidal vascular expansion. These findings highlight the distinct hemodynamic sensitivities of the retinal and choroidal circulations and support OCTA-derived metrics as noninvasive biomarkers for collateral-dependent perfusion.