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
what are the clinical signs of an acute CRVO
Variable visual loss (may have previous transient visual loss), usually painless, photophobia (?)
“Blood and Thunder” fundus!
Retinal haemorrhages, dilated tortuous veins, cotton wool spots, macular oedema, optic disc oedema
what are the 5 main retinal signs of a acute CRVO
retinal haemorrhages - blood and thunder dilated tortuous veins cotton wool spots macula oedema optic disc oedema
how many % of CRVO cases are ischaemic
what signs are seen
what is the prognosis like
20% of CRVO cases
Large areas of retinal capillaries non perfused on Fluorescein Angiography
Severe visual loss
RAPD
Multiple intraretinal haemorrhages + cotton wool spots
Prognosis worse than non ischaemic
how many % of CRVO cases are non-ischaemic
what signs are seen
what differences does it have compared to ischaemic
80% of CRVO cases
Haemorrhage is superficial
Presenting vision better than for ischaemic
Fewer cotton wool spots seen
fundus appearance looks a lot less dramatic than ischaemic
what can be a complication of a CRVO and what 3 things can this complication lead to
Ischaemia causes VEGF upregulation, which can lead to:
Persistent macular oedema
New vessels at disc /elsewhere + vitreous haemorrhage
Neovascular glaucoma – red painful eye, risk of rapid visual loss - VEGF causes new BV growth in the iris near the angle of drainage, blocking drainage of aqueous out of the eye
the complications of CRVO are similar to BRVO but because CRVO has higher level of hypoxia, it’s complications tend to be more severe
what is chronic compensation and which type of occlusion is it related to
CRVO
Chronic compensation:
Optociliary shunt vessels can develop to divert retinal blood to choroidal circulation
what can be the outcome in untreated cases of a CRVO
In non-ischaemic CRVO, macular oedema resolves in ~30% of eyes, neovascular glaucoma is rare.
Up to 30% of nonischaemic CRVO ischaemic in 3 years.
Poorer VA at presentation means poorer VA prognosis.
Eyes with 6/12 VA or better at presentation likely to have better outcome.
80% of eyes with VA worse than 6/60 at presentation do not improve beyond 6/60 over time.
44% of eyes with vision of worse than 6/60 develop rubeosis iridis (risk neovascular glaucoma)
so need to monitor iris as well as retinal appearance
what needs to be managed in a BRVO and a CRVO and what does the RCO recommend its referral procedure should be
Underlying cause (e.g. systemic hypertension) - Refer all cases to GP for investigation
Ophthalmic implications
- Macular oedema
- New vessel growth (retinal and anterior eye)
- Neovascular glaucoma
Royal College of Ophthalmologists: Px should be seen by Ophthalmologist within 2-4 weeks.
what is the ophthalmological treatment for the neovascularisation (retinal and iris/anterior eye) caused by the BRVO and CRVO
Laser panretinal photocoagulation used to treat new vessels in iris / angle and retina.
Evidence that anti-VEGF therapy + photocoagulation has a positive effect.
The laser burns placed across peripheral retina to reduce the oxygen demand of the retina, so reduces retinal hypoxia and hence VEGF
Urgent referral for undiagnosed patients with new vessels.
what is the ophthalmological treatment for the neovascular glaucoma caused by the BRVO and CRVO
Caused by new vessels on iris or angle blocking drainage.
If established and eye is blind (from long standing), aim is to keep eye pain free with topical steroids and atropine.
If vision remains, IOP controlled with drops and/or surgery.
Also if vision is lost, still control IOP to prevent structural damage to the globe itself
Urgent referral
what is the ophthalmological treatment for the macular oedema caused by the BRVO and CRVO
Most common cause of visual loss in patients with RVO.
Traditionally treated with laser photocoagulation.
Steroid injections / implants and anti-VEGF injections have been used more recently.
NICE guidelines currently recommend Ranibizumab (Lucentis) for treatment of visual loss due to macular oedema secondary to CRVO. Also secondary to BRVO when laser photocoagulation not suitable due to extent of macular haemorrhage.
