Retinal Vascular Disease

Loss of vision caused by ischaemic disease of the retina is common. It can be due to several different vascular disorders. Most frequently it is caused by central retinal vein occlusion, diabetes, or occlusion of a branch vein. More rare are vasculitis, retinopathy of prematurity, radiation retinopathy, central retinal artery occlusion, 1Q hypertension and disseminated intravascular coagu lopathy. Occlusion of an artery causes white infarction, while occlusion of veins leads to haemorrhagic infarction. The ischaemic area can vary between focal (occlusion of branch vessels), segmental, or total (occlusion of the central retinal vein or artery). Ischaemia of the retina with damage of retinal vasculature shows leakage of red cells, followed by neovascularisation and formation of microaneurysms. In the final stage, secondary angle closure glaucoma can develop with corneal ulceration and cataract formation, resulting in a not only blind but also painful eye. The globes are often enucleated to relieve pain. At macroscopic examination an ectropion of the iris pigment epithelium, caused by the neovascular membrane on the iris surface is visible (but only if the cornea is transparent). At microscopic examination, the proliferation of endothelial cells in the retina is the most striking finding. Sometimes CD31 and GFAP staining are necessary to differentiate the vascular proliferation from reactive gliosis.

Retinitis pigmentosa presents in early life with night blindness and a progressive reduction in the visual field, starting at the periphery. Retinal architecture remains best preserved at the macula, so the patient ends up with tunnel vision. Different chromosomal abnormalities have been found in patients with retinitis pigmentosa. Microscopic examination shows retinal atrophy with proliferation of Müller cells (retinal supporting cells at the outer side of the retina) replacing the outer nuclear layer. The retinal pigment epithelium proliferates and can surround small hyalinised vessels in the retina. A marked variation in the extent of retinal degeneration can be seen in two relatives with retinitis pigmentosa [117].

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