The distribution of angioarchitectural changes within the vicinity of the arteriovenous crossing in branch retinal vein occlusion

Objective: Branch retinal vein occlusions (BRVOs) are known to occur most commonly in the vicinity of arteriovenous (A/V) crossings. The authors aimed to identify types of venous wall abnormalities in BRVO and document their position in relation to the A/V crossing. Design: A retrospective review of the color photographs and fluorescein angiograms from the most recent 110 patients with first-or second-order BRVO was performed. Main Outcome Measures: The films were examined for the presence of angioarchitectural changes of specified type within one-quarter - disk diameter of the A/V crossing involved in the BRVO. The specific changes noted were fluorescein leakage, presumed thrombi, and flow abnormalities, which were recorded along with their position in relation to the A/V crossing. Results: Of the 110 patients diagnosed with BRVO, 59 had photography of satisfactory quality, Forty-one (70%) of these 59 patients had venous lesions, of which significantly more (chi-square = 5.74, P < 0.02) were downstream (56%) than upstream (12%) from the A/V crossing. Thirty-two percent were upstream and downstream, Of the hemodynamic changes seen, 49% had late venous phase leakage of fluorescein, 85% had abnormal flow, and 7% had presumed thrombi. All thrombi seen were downstream. Conclusions: Venous lesions in the vicinity of the A/V crossing commonly are seen in BRVO, most of which occur downstream. This suggests that the venous narrowing at the crossing may induce downstream hemodynamic changes predisposing to endothelial damage and thrombus generation.