Differentiating between thromboembolic and vasculitic causes is important, as this will influence management. Rapid administration of steroids is required in cases of vasculitic CRAO (e.g. temporal arteritis).
Most cases of CRAO are due to thromboembolism or atherosclerotic disease.
Therefore, risk factors for CRAO are similar to the risk factors for cardiovascular disease. These include:
In addition, carotid artery stenosis is also a significant risk factor for CRAO.
Typical symptoms of CRAO include:
Sudden painless unilateral visual loss: occurs over seconds
Amaurosis fugax: in around 10% of patients
Other important areas to cover in the history include:
Past medical history: atherosclerotic disease or vasculitis
Symptoms of temporal/giant cell arteritis: headaches, temporal tenderness, jaw claudication
Retinal detachment: patients usually describe a ‘curtain’ on their visual field in one eye, some floaters and/or some flashing lights. A detached retina can sometimes be seen on fundoscopy.
Vitreous haemorrhage: blood in vitreous visible on fundoscopy
Retinal vein occlusion: fundoscopy will reveal vascular dilatation and tortuosity of the affected vessels, with associated haemorrhages in that area only
Acute optic neuritis: visual loss is usually accompanied by pain on eye movements and dyschromatopsia (impaired colour vision)
CRAO is a clinical diagnosis, but if there is any doubt then fundus fluorescein angiography and optical coherence tomography may be helpful in confirming the diagnosis.
Other investigations are aimed at identifying the underlying cause.
As CRAO is an ischaemic event, investigations for CRAO are similar to those used for stroke or transient ischemic attack.3
Relevant laboratory investigations include:
ESR and CRP: to exclude temporal/giant cell arteritis
Full blood count: to check for myeloproliferative disorders or anaemia
Coagulation studies (PT and APTT): to screen for coagulation disorders
Depending on individual risk factors and history, other relevant laboratory investigations may include:
HbA1c and lipid profile: to assess for underlying cardiovascular risk factors
Vasculitic screen (ANA, ENA, ANCA, ACE): if vasculitic aetiology is suspected in younger patients
Myeloproliferative or sickle cell disease (blood film): if any abnormalities detected on FBC or no other aetiology identified
Hypercoagulable screen (protein C&S, factor V Leiden, antiphospholipid antibody): to look for coagulation disorders in younger patients
If an embolic cause is suspected, other investigations to consider may include:3
Carotid duplex ultrasound (doppler): to look for carotid artery stenosis
ECG: to look for atrial fibrillation
Echocardiogram: to look for mural thrombus
Ambulatory ECG monitoring: to look for paroxysmal atrial fibrillation
CRAO is an ocular emergency and prompt management is required to prevent visual loss and to protect the other eye, brain and heart from further thromboembolic events.
The aim of management is to attempt to re-perfuse ischaemic tissue as soon as possible and to institute secondary prevention early.2
All patients require an urgent referral to the stroke team and ophthalmology.
If inflammatory markers are elevated and/or the history and examination are consistent with temporal/giant cell arteritis, then high dose steroids should be initiated immediately.3
There are no official guidelines for the treatment of CRAO, and many therapies are of no proven benefit but have anecdotal support and are often tried.
Immediate management options include:1,3
Ocular massage: repeatedly massaging the globe over the closed lid for ten seconds with five-second interludes may occasionally dislodge the obstructing thrombus.
Increase blood oxygen content and dilate retinal arteries: administration of sublingual isosorbide dinitrate or oral pentoxifylline. Inhalation of a carbogen or hyperbaric oxygen.
Reduce intraocular pressure: to increase retinal artery perfusion pressure with intravenous acetazolamide and mannitol, plus anterior chamber paracentesis.
If the patient presents within 24 hours, intra-arterial fibrinolysis through local injection of urokinase into the proximal part of the ophthalmic artery, or intravenous thrombolysis using tissue plasminogen activator (tPA) such as alteplase can be considered, although evidence for such therapies remains equivocal.1
Underlying risk factors should be addressed and modified:2
Diet and lifestyle: a low glycaemic index diet, with adequate levels of vitamin B6 and B12, and regular exercise, will help prevent risk factors such as diabetes and atherosclerosis
Smoking: offer smoking cessation
Hypertension: should be investigated and treated
Hyperlipidaemia: a statin may be initiated
Atherosclerosis: low-dose aspirin may be of benefit
Atrial fibrillation: should be investigated and treated with rate or rhythm control strategy, and anticoagulated unless the risks outweigh the benefits
Carotid artery disease: carotid endarterectomy may be necessary depending on the degree of carotid occlusion and local policy
In the United Kingdom, the Driver and Vehicle Licensing Agency (DVLA) will need to be notified if there is a complete loss of vision in one eye. Patients may still be able to drive after clinical advice and successful adaptation to the condition.
Retinal ischaemia can lead to neovascularisation of the iris and retina around 8 weeks following CRAO.
This can lead to complications such as vitreous haemorrhage and neovascular glaucoma. Patients should be followed up to monitor for such complications up to 4 months after the ischaemic event.1
If at any stage, a patient develops neovascularisation, pan-retinal photocoagulation should be performed.4
Studies have shown that irreversible damage is done to the retina 240 minutes following the occurrence of CRAO.5
Over 90% of patients present with a visual acuity of counting fingers, or less. Even with prompt treatment, the prognosis is poor, although some improvement in visual acuity may be seen in the first 7 days post-CRAO in one-third of patients (with or without treatment).6
Central retinal artery occlusion (CRAO) is the sudden occlusion of the artery supplying the inner retina. It is an ocular emergency.
Embolism is the most common cause of CRAO. The source is often from carotid artery disease or alternatively from the heart in patients with atrial fibrillation (especially in younger patients).
CRAO presents with sudden painless unilateral visual loss. Fundoscopy reveals a pale retina with a cherry-red spot in the centre of the macula.
Although the most common cause is thrombo-embolism, it is crucial to exclude giant cell arteritis (GCA) and other vasculitic causes.
Management is focused on immediate reperfusion of the retina and long-term management of underlying risk factors.
The prognosis for visual recovery is poor, but chances of visual recovery are higher if treatment is given early.
Retinal ischaemia can lead to neovascularisation of the iris and retina around 8 weeks following CRAO. Patients should be followed up to monitor for such complications up to 4 months after the ischaemic event.
Dr Byron Lu Morrell
Dr Chris Jefferies
Varma DD, Cugati S, Lee AW, et al; A review of central retinal artery occlusion: clinical presentation and management. Eye (Lond). Jun 2013. Available from: [LINK]
Lowth M. Retinal Artery Occlusions. Sept 2016. Available from: [LINK]
Rumelt S, Dorenboim Y, Rehany U. Aggressive systematic treatment for central retinal artery occlusion. Am J Ophthalmol. Available from: [LINK]
Cugati S, Varma DD, Chen CS, et al; Treatment options for central retinal artery occlusion. Curr Treat Options Neurol. Feb 2013. Available from: [LINK]
Hayreh SS, Zimmerman MB, Kimura A, Sanon A. Central retinal artery occlusion. Retinal survival time. Exp Eye Res. Mar Available from: [LINK]
Hayreh SS, Zimmerman MB. Central retinal artery occlusion: visual outcome. Am J Ophthalmol. Sep 2005. Available from: [LINK]
Figure 1. Adapted by Geeky Medics. Achim Fieß, Ömer Cal, Stephan Kehrein, Sven Halstenberg, Inezm Frisch, Ulrich Helmut Steinhorst. Cherry Red Spot Fiess. License: [CC-BY].