THE DISTRIBUTION OF ANGIOARCHITECTURAL CHANGES WITHIN THE VICINITY OFTHE ARTERIOVENOUS CROSSING IN BRANCH RETINAL VEIN OCCLUSION

Objective: Branch retinal vein occlusions (BRVOs) are known to occur m ost commonly in the vicinity of arteriovenous (A/V) crossings. The aut hors aimed to identify types of venous wall abnormalities in BRVO and document their position in relation to the A/V crossing. Design: A ret rospective 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 pres ence of angioarchitectural changes of specified type within one-quarte r - disk diameter of the A/V crossing involved in the BRVO. The specif ic changes noted were fluorescein leakage, presumed thrombi, and flow abnormalities, which were recorded along with their position in relati on to the A/V crossing. Results: Of the 110 patients diagnosed with BR VO, 59 had photography of satisfactory quality, Forty-one (70%) of the se 59 patients had venous lesions, of which significantly more (chi-sq uare = 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 flu orescein, 85% had abnormal flow, and 7% had presumed thrombi. All thro mbi seen were downstream. Conclusions: Venous lesions in the vicinity of the A/V crossing commonly are seen in BRVO, most of which occur dow nstream. This suggests that the venous narrowing at the crossing may i nduce downstream hemodynamic changes predisposing to endothelial damag e and thrombus generation.