ABSTRACT
There are a number of conditions that stimulate new blood vessel formation (neovascularisation [NV]) of the retina. These blood vessels are fragile, risking vitreous haemorrhage (VH) and associated with fibrosis and contraction causing tractional retinal detachment (TRD). The most common condition is severe diabetic retinopathy; others are retinal vein occlusion (RVO), sickle cell retinopathy and retinal vasculitis. This is the most common cause of haemorrhage into the vitreous. Haemorrhage may occur into the gel, retrohyaloid space or, rarely, subretinal space. Severe retrohyaloid haemorrhage may cause the posterior vitreous face to bulge forward into bullae, looking slightly like retinal detachment to the unwary. The areas of detachment surround NV on the retinal arcades and are often multifocal. Eventually, the macula detaches severely reducing the visual acuity (VA), while the periphery remains flat. RVOs are the second commonest vascular events in the eye after diabetic retinopathy. The eye is unusual in suffering from occlusion of the veins more often than arteries.
