- perfusion - 75% non-ischaemic - 2/3 with ischaemic type develop macular oedema, macular ischaemia, and neovascularization that leads to blindness - epidemioloy - age usually 60-70 - occlusion of a primary branch involving approximately half the retina is a hemiretinal vein occlusion; a more distal branch is a called branch retinal vein occlusion - often asymptomatic **risk factors** - HTN - [[Glaucoma]] - diabetes - atherosclerosis - hyperviscosity # assessment - onset over *minutes* - [[Painless loss of vision]] - no floaters or photopsia - can usually count fingers - visual acuity and presence of [[Relative afferent pupillary defect|RAPD]] are variable depending on severity - abnormal [[red reflex]] - tomato sauce retina - dilated tortuous veins ![[Painless loss of vision#Central retinal artery occlusion CRAO vs Central retinal vein occlusion CRVO]] ![[Pasted image 20240328192712.png| blood and thunder appearance]] # management - prevent neovasculraisation - diagnosis and treatment of underlying condition