Retinal and Choroidal Vascular Alterations in Carotid Dissection Versus Atherosclerosis: Insights Into Divergent Ischemic Mechanisms

Background To contrast retinal and choroidal vascular alterations between carotid artery dissection (CAD) and carotid artery stenosis (CAS), and analyze their associations with cerebral infarction patterns and stenosis severity. Methods This observational study included stenotic‐degree‐matched patients with CAD and patients with CAS. Retinal ischemic signs—cotton wool spots, retinal artery occlusion, and paracentral acute middle maculopathy—were evaluated using fovea‐centered optical coherence tomography/angiography. Retinal vascular density and choroidal metrics (choriocapillaris density, thickness, vascular volume, and index) were analyzed. Results The final analysis included 863 eyes from 467 participants (85 with CAD, 274 with CAS, 108 controls). Patients with CAD showed a significantly higher prevalence of paracentral acute middle maculopathy than Patients with CAS (6.4% versus 0.61%, P <0.001). Although ipsilateral eyes in both groups showed reduced retinal vascular density ( P <0.017), a divergent pattern was observed in the choroid: CAD‐affected eyes demonstrated significantly higher choriocapillaris density, choroidal vascular volume, and choroidal thickness relative to both control and CAS‐affected eyes ( P <0.017). Clinically, retinal ischemic signs in CAD were significantly associated with cerebral infarction ( P =0.022) and severe stenosis/occlusion ( P =0.008). Notably, retinal signs correlated with cerebral infarction topography: subcortical infarctions were predominantly associated with paracentral acute middle maculopathy, whereas cortical infarctions were linked to cotton wool spots and retinal artery occlusion ( P =0.004). Conclusions Compared with atherosclerotic stenosis, CAD exhibits a distinct oculovascular phenotype characterized by a higher burden of acute retinal ischemia but compensatory choroidal hyperperfusion. Retinal imaging serves as a noninvasive window into CAD pathophysiology, offering biomarkers for assessing hemodynamic stability and thromboembolic risk. Registration URL: www.chictr.org.cn ; Unique identifier: ChiCTR2300074640.