Arteriovenous Crossing Patterns in Branch Retinal Vein Occlusion

ABSTRACT

The study was designed to evaluate the relative anatomic position of the crossing vessels at the site of occlusion in eyes with branch retinal vein occlusion(BRVO). Fluorescein angiography and fundus photography of 33 eyes(33 patients) with BRVO were used to examine the relative position of artery and vein at occluded crossings. Three separate comparison groups were formed by identifying corresponding arteriovenous crossings for each occluded crossing in (1) the ipsilateral but opposite vessel arcade within eyes affected by BRVO patients; (2) the same quadrant in unaffected eyes of BRVO patients; and (3) the same quadrant in eyes of patients without BRVO, matched by age and sex with the BRVO patients. The site of obstruction of the branch vein was an arteriovenous crossing in all affected eyes. In 97% of eyes with BRVO, the artery was located anterior to the vein at the obstructed site. In the three comparison groups the artery was anterior to the vein in 73%, 68%, 59% of the crossings, respectively, yielding statistically significant differances for first group(P<0.02), second graup(P<0.01) and third group(P<0.001) of control crossings compared with BRVO crossings.