Vascular disease: retinal artery occlusions Flashcards
what causes a CRAO and possibly a BRAO
Occlusion of central retinal artery (CRAO), usually by a fibrin-platelet thrombus or an embolus.
Occlusion of branch retinal artery (BRAO) also possible
what other vascular disorders to retinal artery occlusions share it’s risk factors with and list the 5 risk factors
factors with other vascular diseases e.g.
hypertension hyperlipidaemia tobacco use atherosclerosis Diabetes Mellitus
as well as occlusions of the CRA and BRA, what can be another cause to a CRAO or BRAO and name 2 conditions that can cause this
Can also be caused by vascular inflammatory conditions
e.g. giant cell arteritis, systemic lupus erythematosus
what does a CRAO/BRAO indicate
what is the life expectancy of someone with a CRAO compared to someone without a CRAO
Indicates increased risk of life-threatening cerebrovascular or cardiovascular incident.
Life expectancy 5.5 years compared to 15.4 years for age matched population without CRAO
what is the clinical presentations of a CRAO/BRAO
Sudden, severe, painless loss vision.
~90% px with CRAO have vision between counting fingers and light perception at presentation.
1-2% bilateral presentation.
Mean age early 60s.
May have history of amaurosis fugax (transient loss of vision lasting seconds-2 hours – vision returns to normal afterwards).
With branch occlusion, extent of visual loss will depend on location of occlusion.
what are the 5 signs of an acute CRAO/BRAO
Inner layers of the retina become oedematous and milky/opaque.
Opacity greatest at macula where RNFL and RGC layers thickest.
Ischaemic necrosis results from the disrupted blood supply
Fovea shows a ‘cherry red spot’ because fovea is nourished/being provided for by underlying choroidal circulation so it’s not becoming ischaemic, and because retina is thinnest here so underlying choroid seen.
Blood moves sluggishly in occluded vessels and blood flow may appear segmented (‘boxcarring’ or ‘cattle tracking’)
what are the 3 signs of a chronic CRAO/BRAO
Retinal opacification evident within 15 mins-2 hours.
Resolves in 4-weeks.
Chronic appearance of attenuated retinal arterioles and optic nerve atrophy.
Homogenous scar replaces inner retinal layers
what is seen on the fundus in 20-40% of cases
embolus or thrombus seen
what is the appearance of 2 types of embolus and a thrombus seen on the retina in 20-40% of cases
- Glistening yellow cholesterol emboli often from atherosclerotic plaques in carotid artery
- Calcific emboli typically from cardiac valves
- non-glistening platelet-fibrin thrombus typically seen at optic disc
what 2 things can happen to an emboli and what may this emboli cause
Emboli may dislodge after causing temporary visual loss (amaurosis fugax) which will retire to normal
They may get trapped at a bifurcation/at branching of vessel and not obstruct flow.
May cause CRAO or BRAO.
what should you do with patients with retinal emboli or history of transient painless visual loss
should be referred for urgent cardiovascular assessment
what is the outcomes of a CRAO/BRAO
Visual loss usually severe.
Field defect most commonly central in CRAO – peripheral fields more likely to recover.
Any spontaneous recovery in vision usually occurs within first 7 days - beyond 7 days = visual loss is often permanent
In 10% of eyes with a cilioretinal artery supplying the fovea VA returns to 6/7.5 or better in 80% of eyes within 2 weeks.
Retinal or anterior eye neovascularisation may be possible longer term complications.
what will be your management of a patient seen with a CRAO/BRAO
OCULAR EMERGENCY!!!
- Any treatment outside 4 hour window unlikely to improve vision. If vision loss has occurred within last 24 hours
- phone casualty immediately.
In practice can do the following:
- Ask px to lie flat (raises pressure in ophthalmic artery)
- Ocular massage may help to dislodge the embolus – press on eye with heel of hand (10 sec on, 10 sec off for 5 mins).
- Can ask Px to breath into paper bag – increased CO2 levels will cause vasodilation and may help to dislodge the embolus
- But best to get them to casualty ASAP!
why you need to refer a px with CRAO/BRAO due to an emboli and due to arteritic inflammation cause urgently
Patients with CRAO/BRAO due to emboli are at high risk of stroke / heart attack – need urgent referral for medical assessment even if window of opportunity for vision restoration has passed.
Arteritic CRAO/BRAO due to temporal (giant cell) arteritis also needs urgent treatment. Visual outcome worse due to concurrent arteritic anterior ischaemic optic neuropathy
which cause of a CRAO/BRAO has a worse visual outcome and why
Arteritic due to temporal (giant cell) arteritis
ue to concurrent arteritic anterior ischaemic optic neuropathy
