Vessel Position of the Arteriovenous Crossing in Branch Retinal Vein Occlusion

Abstract

Purpose : Controversy exists regarding the anatomical vessel position of the affected arteriovenous (AV) crossing in eyes with branch retinal vein occlusion (BRVO); previous investigations using conventional imaging modalities including color fundus photographs (CFP) reported that, in BRVO, arterial overcrossings were dominant and venous overcrossings were very rare, but in our previously published case series, investigations using optical coherence tomography (OCT) and OCT angiography (OCTA) suggested that BRVO characterized by venous overcrossing was more prevalent than previously reported. We thus performed an observational study using a larger case series to clarify the anatomical vessel position of BRVO-affected AV crossings.

Methods : We included both eyes of 68 patients with unilateral non-acute BRVO (136 eyes) and of 92 subjects without any retinal vascular disease (184 eyes). To cover the area within retinal vascular arcades, we used 45° CFP and OCTA (Angioplex Elite 9000) over 12×12 mm². In each AV crossing site where all first- and second-order retinal veins and arteries associated, we divided the crossing pattern into arterial or venous overcrossing and compared crossing pattern proportions at (1) BRVO sites, (2) unaffected crossing sites of BRVO-eyes, (3) crossing sites of fellow eyes, and (4) crossing sites of control eyes.

Results : We examined 736 AV crossings of BRVO patients, and 958 crossings of non-BRVO subjects. Compared to two-dimensional CFP, high-depth-resolution OCTA enabled observation of narrowed veins and their three-dimensional vessel positions at AV crossing sites. The proportion of arterial and venous overcrossings at (1)-(4) were 85% vs 15%, 72% vs 28%, 60% vs 40%, and 64% vs 36%, respectively, on CFP and 51% vs 49%, 76% vs 24%, 70% vs 30%, and 75% vs 25%, respectively, on OCTA. Determined patterns were similar between CFP and OCTA in crossings at (2)-(4) but were often inconsistent between modalities in crossings at (1). In (1), 40% (23/58) of arterial overcrossing categorized on CFP was categorized as venous overcrossing on OCTA.

Conclusions : OCTA enabled more accurate determination of anatomical vessel position of AV crossing than CFP. Proportion of venous overcrossing in BRVO examined by OCTA was higher than that in previous reports and at other sites [(2)-(4)]. Thus, a venous overcrossing pattern may indicate higher risk for BRVO.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.