Vascular disease: retinal vein occlusion Flashcards
what other vascular disease is RVO most common after
diabetic retinopathy
what is the most common type of RVO
branch RVO
where in the retina may the branch RVO occur and how does it cause this
Typically occurs at AV crossing - where theres a/v nipping and deflection of the vein at crossings
Venous compression by the artery may result in turbulent blood flow through the vein, endothelial damage, thrombosis and occlusion
More likely when artery is sclerosed
what is the avg age of occurrence of a BRVO
what are the 7 risk factors of a BRVO (list the main one first)
avg occurrence 60 y/o
Risk factors:
- systemic hypertension (50%)
- hyperlipidaemia - another vascular cause
- cardiovascular disease - another vascular cause
- a history of glaucoma
- short axial length
- previous RVO in either eye
- inflammatory conditions (e.g. sarcoidosis, Lyme disease)
what is a protective factor of a BRVO i.e. less chance of it happening
Where vein crosses artery instead of artery crossing vein
wha are the 4 main symptoms of a BRVO
Often superior temporal in presentation (~66% cases) = infer-nasal vf affected
May present with sudden onset, painless loss of vision
May be asymptomatic (usually if nasal branch)
May result in sector field defect or central field defect (if macular branch, ~25% cases)
when will a central field defect occur with a BRVO and what is the prevalence of these cases
if the macular branch is affected - px will be symptomatic
~25% of BRVO cases
what are the 4 signs of an acute/new case of BRVO and what pattern do all of these signs follow/have in common
Haemorrhages (often flame shaped)
Vessels dilated and tortuous distal to occlusion
Retinal oedema (fluid leakage)
Cotton wool spots
Signs follow distribution of vessel, usually respect horizontal raphe
what are the 4 signs of a chronic/longterm case of BRVO and what is the cause of these signs
Hard exudates
Vascular sheathing (appear white)
Macular pigment
New vessel formation (small and tortuous, may cross horizontal raphe to drain into unaffected quadrant)
caused by:
Retinal ischaemia occurs downstream to occlusion and this leads to VEGF up regulation which causes increased vessel permeability causing macular oedema
what sign can be largely resolved and what can still be present in a chronic BRVO
haemorrhage largely resolved
substantial exudates still seen
vascular sheathing seen (some vessels look like they’re completely white in colour)
what can be the 3 main complications of a BRVO
Macula: Chronic macular oedema (main cause visual loss), exudates, haemorrhage, epiretinal membrane
Neovascularisation at disc or elsewhere and vitreous haemorrhage if large area of the retina is ischaemic
Rarely, retinal detachments (rhegmatogenous, tractional)
what are the untreated outcomes of a BRVO
what to expect if a BRVO is not treated at all:
Macular oedema often resolves - within 12 months in ~40% of cases
~50% of eyes maintain VA equal or better than 6/12
~25% of eyes will be equal or worse than 6/60
BRVO occurs in fellow eye in 10% of cases
Neovascular glaucoma is rare
Retinal neovascularisation can occur (3 yr incidence ~10%)
what causes a central RVO
by thrombus formation where central retinal artery and vein leave the optic nerve head, often at lamina cribrosa
so when the entire central retinal vein is occluded
what are the 5 risk factors for a CRVO
Systemic hypertension Diabetes mellitus Open-angle glaucoma Cardiovascular disease Systemic inflammatory conditions
how can open angle glaucoma cause a CRVO
because the increased pressure in the eye can cause the vein to get squashed at the level of the lamina cribrosa
