ARTERIOVENOUS CROSSING AS A RISK FACTOR IN BRANCH RETINAL VEIN OCCLUSION

To evaluate the importance of the position of the artery anterior to t he vein in the arteriovenous crossing to the pathogenesis of first- an d second-order branch retinal vein occlusion, we studied the fluoresce in angiograms of 65 patients with branch retinal vein occlusion (65 ey es). The corresponding crossing in the opposite arcade (superior or in ferior) served as the control. In a statistically significant percenta ge of crossings, the arteries were anterior to the veins in second-ord er branches (odds ratio, 6.66; 95% confidence interval, 1.98 to 32.33; chi(2), 12.56; P = .000394). However, their position was not found to be important in the pathogenesis of first-order occlusions (odds rati o, 1.3; 95% confidence interval, 0.23 to 9.01; chi(2), 0.14; P = .7082 81). These results suggest that some differences may exist in the risk factors for branch retinal vein occlusion depending on the site of th e occlusion.