Definition

Retinal vein occlusion (RVO) is a heterogeneous group of retinal vascular diseases that differ in pathogenesis, clinical aspects, course, and complications. The occlusion may concern the central retinal vein (CRVO) or only a branch of it and, in this case, we speak of Branch Retinal Vein Occlusion (BRVO).  

Symptomatology

Retinal venous occlusions result in severe deterioration of visual function and occur when the circulation of a retinal vein is obstructed. Consequences are the formation of retinal hemorrhages and, very commonly, the development of ischemic areas (poorly sprayed areas) and/or macular edema.

Diagnostics

Early diagnosis and treatment go through a series of diagnostic examinations: ophthalmoscopy, biomicroscopic examination of the ocular fundus, fluoroangiography and OCT (useful especially in patient follow-up). In young people with RVO, aged 43-69 years, the increased risk of cardiovascular mortality requires primary prophylaxis of cardiovascular events by long-term treatment with antithrombotic drugs. The main predisposing factors are certainly cardiovascular risk factors such as arteriosclerosis, arterial hypertension, diabetes mellitus, hyperlipidemia, obesity, smoking, carotid occlusion. Other important risk factors are rheological modifications (increased hematocrit, increased plasma viscosity, increased red blood cell aggregation, reduced red blood cell deformability). Alterations of plasma viscosity are extremely important, while other risk factors concern the thrombophilic state: hyperomocysteinemia, anti-phospholipid antibodies, Activated protein C resistance (Leiden factor V), mutations, reduced levels of plasminogen inhibitors, oral contraceptives. Finally, there are also local risk factors: glaucoma, trauma, retinal vasculitis, occlusion of the central artery; all conditions that cause a reduction of the channel of the lamina cribrosa such as drusen, papilledema; arteriovenous malformations that cause venous hypertension; hyperviscosity syndrome (polycythemia, macroglobulinemia, myeloma, leukemia). 

Therapy

In retinal vascular diseases, the use of intravitreal therapies, i.e. the use of anti-VEGF drugs, induces an improvement in visual acuity and a reduction in macular thickness. Multiple injections (repetition of the procedure) or slow-release intravitreal implant are required. The laser, on the other hand, can intervene in the treatment of complications (macular edema or neovascularization). Particular clinical conditions justify the surgical approach.