Retinal vein thrombosis: risk factors, pathogenesis and therapeutic approach.

Retinal vein occlusion (RVO) is a relatively common disease, often associated with the presence of diseases related to internal medicine. It is well known that RVO is associated with common systemic vascular disorders such as hypertension, arteriosclerosis and diabetes. Several studies using hospital-based controls have shown an increased risk of RVO in patients with arteriopathy, or high levels of plasma glucose and arterial blood pressure. Patients are categorized into six types of RVO based on the site of occlusion and on the type of consequent vascular damage. Central retinal vein occlusion (CRVO) is the most frequently-occurring and clinically relevant type of RVO. In addition to the well-known classical risk factors, new haemostasis-related ones have been investigated in patients affected by CRVO. While data concerning a number of parameters remain contradictory, high levels of type 1 plasminogen activator inhibitor (PAI-1) and hyperhomocysteinemia appear to play a significant role in the pathogenesis of this disease. Although based on a limited number of studies, this new knowledge could eventually provide important indications regarding prognosis and therapeutic strategies. There is no established treatment for CRVO. Treatment consists primarily of managing any identified underlying systemic disease. The increasing role of hypercoagulability in patients with CRVO supports the use of antithrombotic drugs in the treatment of this disease. Vitamin treatment to correct hyperhomocysteinemia should also be taken into consideration. However, the approach to CRVO treatment with antithrombotic drugs is not evidence-based yet. There is urgent need of intervention trials to evaluate the role of these drugs in CRVO patients.