Acute Branch Retinal Vein Occlusion with Spillover Involvement of an Adjacent Retinal Region

A 60 year - old hypertensive man was seen complaining of blurred vision on the left for 4 weeks. An inferotemporal BRVO of the left eye was found. Intraretinal hemorrhage extended far beyond the boundaries of the inferotemporal sector of retina. In the figure, the purple line indicates the horizontal raphe. The yellow oval indicates superotemporal retina with extensions of hemorrhage. There are anastomoses between superotemporal retinal capillaries and inferotemporal retinal veins. Thus when intravenous pressure in the inferotemporal veins dramatically rises in the event of a branch retinal vein occlusion, the increase in intravascular pressure is transmitted backwards to some of the superotemporal capillaries with resultant extravasation of blood into the interstitium.