Appearance of Thrombus Downstream of Arteriovenous Crossing with Branch Retinal Vein Occlusion
A 69 year old woman with hypertension, hypercholesterolemia, and obstructive sleep apnea syndrome developed a left superotemporal BRVO. A - Magnified view of the arteriovenous crossing where the thrombus is located. The artery crosses the vein at the black arrow. The blue arrow denotes thrombus with white fibrin marbling downstream of the involved arteriovenous crossing. The red circle encompasses a cotton wool spot. B - A frame from the early phase fluorescein angiogram shows delayed filling of the superotemporal retinal vein. C - Frame from the mid-phase fluorescein angiogram. The thrombus downstream of the crossing is hyperfluorecent due to pooling of stagnant fluorescein trickling through the occlusion (blue arrow). The orange arrow shows speckled hyperfluorescence in a dilated upstream section of the obstructed vein, a sign of sluggish blood flow. The green arrow denotes stained venules in the involved retina, a sign of ischemia. The yellow oval encircles a zone of poor capillary perfusion. The red oval encircles the area of the cotton wool spot (compare A), which in the fluorescein angiogram blocks the capillary detail. D - Frame from the late phase fluorescein angiogram. Most of the involved retina shows extreme hypermeability of microvasculature (hyperfluorescence), but the nonperfused areas are relatively hyperfluorescent (yellow oval).