There exist two types of retinal vein occlusion: the Central Retinal Vein Occlusion, CRVO, caused by the obstruction of the principal vein of the retina, and the Branch Retinal Vein Occlusion, BRVO, caused by the obstruction of a branch of the principal retinal vein.
The retinal vein occlusion can cause very serious ocular complications, among which the most common are vitreal hemorrhage, cystoid macular edema, retinal neovascularization and iris neovascularization, with consequent neovascular glaucoma.
Some individuals are subject to a higher risk for retinal vein occlusion. This can be due to a particular anatomical conformation of the blood vessels of the retina and the existence of pathologies such as diabetes, glaucoma, high blood pressure, age linked vascular pathologies and some blood pathologies.
Moreover, a past BRVO event in one eye entails a greater probability (approximately 10%) that a second event of BRVO or CRVO can occur in the other eye, within five years after the initial thrombotic event.