Recent UpdatesIn Retinal Vein Occlusion

Abstract

RVO is the second mostcommon retinal vascular disease after diabetic retinopathy.There are two types of retinal vein occlusion (RVO): central retinal veinocclusion (CRVO) and branch RVO (BRVO).Both CRVO and BRVO can be broadly classified into ischaemic and non-ischaemic types based on the area of capillary non-perfusion, and this distinction is useful for clinical management. Central retinal vein occlusion (CRVO) results from thrombosis of the central retinal vein when it passes through the lamina cribrosa. Branch retinal vein occlusion (BRVO) is caused by venous thrombosis at an arteriovenous crossing. Hypertension is a major risk factor for RVO. Other associated risk factors include hyperlipidemia, smoking, history of cardiovascular disease, Hyperhomocysteinaemia, Blood coagulation disorders and glaucoma. Thrombosis of the retinal veins causes an increase in retinal capillary pressure resulting in increased capillary permeability and leakage of fluid and blood into the retina. Co-existent retinal ischaemia may exacerbate this process by the production of vascular endothelial growth factor (VEGF) which in turn promotes retinal capillary permeability resulting in further development of ME, and promote new vessel formation principally but not exclusively involving the iris and angle in CRVO and the retina in BRVO. These complications can lead to neovascular glaucoma, vitreous haemorrhage and tractional retinal detachment with severe visual impairment.