Central retinal arterial occlusion Flashcards
Describe the pathophysiology of central retinal artery occlusion:
occlusion of the retinal artery results in hypoperfusion of the retina, hypoxic damage, retinal cell death and visual loss
What is the most common cause of central retinal artery occlusion?
embolism
Give 2 common origins of central retinal artery emboli:
- Carotid artery
- heart in AF
What is the second most common cause of central retinal artery occlusion?
in-situ thrombosis
What are 4 causes of in-situ retina artery thrombosis?
- Atherosclerotic disease
- Vasculitis
- Inflammatory disorders
- Hypercoagulable states
Give 7 risk factors for central retinal artery occlusion:
- Hyperlipidaemia
- Hypercoagulable states
- Hypertension
- Carotid artery stenosis
- Smoking
- Male
- diabetes
Give 6 chronic conditions that predispose to thrombosis:
- sickle cell anaemia
- multiple myeloma
- SLE
- Factor V leiden
- temporal/ giant cell arteritis
- anti-phospholipid syndrome
What is the characteristic presenting symptom associated with central retinal artery occlusion?
sudden, painless unilateral vision loss that occurs over second
What sign is seen when testing pupillary reflex in an eye affected by central retinal artery occlusion?
relative afferent pupillary defect
What fundoscopy sign is associated with central retinal artery occlusion?
pale retina with central cherry red spot
Why does the retina appear pale?
due to oedema
What causes the cherry red spot?
cherry-red spot is from the thin fovea revealing the preserved underlying choroidal circulation.
With central retinal artery occlusion being a clinical diagnosis, what two tests can be used if there is any doubts?
- Fluorescein angiography
- Optical coherence tomography
What is fluorescein angiography?
An eye test that involves injection of a fluorescent dye to examine blood flow.
What are 3 laboratory investigations indicated when central retinal artery occlusion is indicated?
- ESR and CRP to exclude temporal/giant cell arteritis
- FBC to check for anaemia and myeloproliferative disorders
- Coagulation studies to check for coagulation disorders
If an embolic cause is suspected, what 4 other investigations may be considered?
- Carotid duplex ultrasound (carotid artery stenosis)
- ECG (AF)
- Echocardiogram (mural thrombus)
- Ambulatory ECG monitoring (to look for paroxysmal atrial fibrillation)
What drug is used in intra-arterial fibrinolysis of the retinal artery within 24 hours?
local injection of urokinase
What class of drug is used for IV thrombolysis for central retinal artery occlusion?
tissue plasminogen activator
Give an example of a tissue plasminogen activator (tPA)?
alteplase
Give two clot busting techniques that can be used within the first 24 hours of central retinal artery occlusion:
- Intra-arterial fibrinolysis
- IV thrombolysis
What are 2 non-clot busting techniques used to treat central retinal artery occlusion?
- Ocular massage
- Reduce intraocular pressure using IV acetazolamide and mannitol to increase retinal artery perfusion pressure
What drug class should be given to vasculitis-associated central retinal artery occlusion?
high-dose steroids
What is used to increase blood oxygen content and dilate retinal arteries?
administration of sublingual isosorbide dinitrate or oral pentoxifylline. Inhalation of a carbogen or hyperbaric oxygen
Why does central retinal artery occlusion increase the risk of vitreous haemorrhage and neovascular glaucoma?
it causes neovascularisation in the weeks following the episode
Give two complications of central retinal artery occlusion:
1) neovascular glaucoma
2) vitreous haemorrhage
How long must ischaemia to the retina last in order to cause irreversible damage?
4 hours
