Section 1 Introduction
1.1 Background
Retinal vein occlusion (RVO) is a common cause of visual loss in the United Kingdom. It is an obstruction of the retinal venous system by thrombus formation and may involve the central, hemi-central or branch retinal vein.1-3 Other possible causes are external compression or disease of the vein wall e.g. vasculitis. Retinal vein occlusions are the second commonest cause of reduced vision due to retinal vascular disease4,5with BRVO occurring 2-3 times as common as CRVO.6,7 In the Australian population study the incidence was 0.7% at 49-60yrs and 4.6% at 80yrs.7 It typically occurs in middle aged and elderly patients (i.e over age of 50 years) with equal sex distribution in both branch retinal vein occlusion (BRVO) and central retinal vein occlusion (CRVO). CRVO is classically characterised by disc oedema, increased dilatation and tortuosity of all retinal veins, widespread deep and superficial haemorrhages, cotton wool spots, retinal oedema and capillary non-perfusion. In less severe forms the disc oedema may be absent. BRVO has similar features except that they are confined to a portion of the fundus. In view of the significant ophthalmological and medical consequences of retinal vein occlusion, these guidelines promote a good standard of practise and the achievement of best visual and medical outcome.

1.2 Remit of the guidelines
These guidelines provide recommendations for the diagnosis and ophthalmological
management of central, branch, and hemispheric retinal vein occlusion. They also
consider the risk factors for the disease and include recommendations for
investigations and indications for medical management. They are intended for the
use of ophthalmologists but may be useful for physicians and general practitioners.

Introduction Methods used Risk factors CRVO
BRVO Medical treatment Cardiovascular problems Young patient
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