Retinal Arterial Vasospasm in Retinal Vein Occlusion and Its Association with Aqueous Humor Endothelin-1

Abstract

IntroductionTo determine the incidence, clinical characteristics, and spatial associations of retinal arterial vasospasm in retinal vein occlusion (RVO), and to explore its relationship with aqueous humor endothelin-1 (ET-1) concentration.MethodsThis retrospective cohort study included 58 eyes with RVO that underwent wide-field fluorescein angiography (FA) within 1 month of presentation. In addition, aqueous humor samples were prospectively collected from a subset of 18 treatment-na & iuml;ve RVO eyes. Arterial vasospasm was defined as a focal narrowing of the arterial lumen on early-phase FA. Cotton wool spots (CWS) and retinal hemorrhage were evaluated using color fundus photography and electronic medical records. Topographic concordance was assessed using quadrant-based, horizontal, and vertical hemifield classifications. Aqueous humor samples were analyzed for ET-1 concentration using enzyme-linked immunosorbent assay (ELISA).ResultsArterial vasospasm was identified in 21 eyes (36.2%), including six eyes with central RVO and 15 eyes with branch RVO. Vasospasm was most commonly observed in the superotemporal quadrant and predominantly on second-order arteriolar branches (78.6%). CWS were more frequent in eyes with vasospasm compared with those without (81.0% vs. 54.1%; p = 0.050). Significant spatial concordance between vasospasm and CWS was observed in the vertical hemifield (p = 0.049), with no concordance observed with retinal hemorrhage location or severity. Exploratory aqueous humor analysis showed higher ET-1 concentrations in eyes with vasospasm (8.37 +/- 4.59 vs. 5.74 +/- 1.88 pg/mL), although statistical interpretation was limited by the sample size.ConclusionRetinal arterial vasospasm is a relatively common but under-recognized feature of RVO. Its association with CWS and higher ET-1 levels suggests localized arterial endothelial dysfunction. Vasospasm may represent an arterial component of RVO pathophysiology and warrants further investigation.