Central Retinal Artery Occlusion

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Central retinal artery occlusion (CRAO)\: Sudden occlusion of the retinal artery causing retinal hypoperfusion, hypoxic
damage, cell death, and visual loss.
Ophthalmic emergency\: Prompt diagnosis and treatment are essential to restore retinal perfusion and minimise visual loss.
Incidence\: Approximately 1 in 100,000/year, predominantly a
Common causes\: Embolism (from carotid artery disease or heart in atrial
atherosclerotic disease, vasculitis, in
Risk factors\: Hypertension, smoking, hyperlipidaemia, diabetes, hypercoagulable states, male gender, carotid artery
stenosis.
Symptoms\: Sudden painless unilateral visual loss (occurs over seconds), amaurosis fugax (in around 10% of patients).
Clinical
central cherry-red spot on fundoscopy.
Di
Investigations\: ESR, CRP, FBC, coagulation studies, HbA1c, lipid pro
screen. Carotid duplex ultrasound, ECG, echocardiogram, ambulatory ECG monitoring if embolic cause suspected.
Management\: Urgent referral to stroke team and ophthalmology. Immediate options include ocular massage, increasing
blood oxygen content and dilation of retinal arteries (e.g by administration of sublingual isosorbide dinitrate), reducing
intraocular pressure (e.g with IV acetazolamide and mannitol). Intra-arterial
considered within 24 hours.
Long-term management\: Address and modify underlying risk factors such as diet, lifestyle, smoking cessation,
hypertension, hyperlipidaemia, atrial
Complications\: Neovascularisation of iris and retina, vitreous haemorrhage, neovascular glaucoma. Follow-up to monitor
for complications up to 4 months post-CRAO.
Prognosis\: Irreversible damage to retina within 240 minutes post-CRAO. Poor prognosis with over 90% presenting with
visual acuity of counting
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A comprehensive topic overview

Introduction

Central retinal artery occlusion (CRAO) is the sudden occlusion of the artery supplying the inner retina leading
to hypoperfusion of the retina, hypoxic damage, retinal cell death and visual loss.
CRAO is the ophthalmic equivalent of a stroke and is an ophthalmic emergency. Prompt diagnosis and treatment are
essential to restore retinal perfusion and minimise cellular damage and visual loss.
It has an incidence of approximately 1 in 100,000/year and predominantly a
1Aetiology
The most common cause of CRAO is embolism. The source is often from carotid artery disease or alternatively from the
heart in patients with atrial
2
CRAO can also be caused by in-situ thrombosis, which can result from atherosclerotic disease, vasculitis, in
disorders, and/or hypercoagulable states.
Conditions predisposing to thrombosis include sickle cell anaemia, multiple myeloma, systemic lupus erythematosus,
Factor V Leiden, polyarteritis nodosa, temporal/giant cell arteritis, antiphospholipid syndrome, and Behcet's disease among
others.
1
Di
administration of steroids is required in cases of vasculitic CRAO (e.g. temporal arteritis).

Risk factors

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\:
Hypertension
Smoking
Hyperlipidaemia
Diabetes
Hypercoagulable states
Male gender
In addition, carotid artery stenosis is also a signi

Clinical features

History
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
Clinical examination
In the context of suspected CRAO, a thorough eye examination including fundoscopy is required.
Typical clinical
Profound unilateral reduction in visual acuity (usually reduced to counting
Relative a
Pale retina with a central cherry-red spot on fundoscopy
The retina appears pale due to oedema, and the cherry-red spot is from the thin fovea revealing the preserved underlying
choroidal circulation.Figure 1. Fundoscopic features of central retinal artery occlusion (CRAO).
A physical examination should also be undertaken to identify an underlying cause, paying particular attention to\:
Pulse rate and rhythm
Blood pressure
Carotid bruits
Signs of temporal arteritis (scalp tenderness, nodular temporal arteries)
Signs of connective tissue diseases that could predispose to vasculitis in younger patients

Di

Other causes of sudden-onset unilateral painless visual loss to consider include\:
2
Retinal detachment\: patients usually describe a ‘curtain’ on their visual

Vitreous haemorrhage\: blood in vitreous visible on fundoscopy
Retinal vein occlusion\: fundoscopy will reveal vascular dilatation and tortuosity of the a
haemorrhages in that area only
Acute optic neuritis\: visual loss is usually accompanied by pain on eye movements and dyschromatopsia (impaired
colour vision)

Investigations

CRAO is a clinical diagnosis, but if there is any doubt then fundus
tomography may be helpful in con
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
Laboratory investigations
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 pro
Vasculitic screen (ANA, ENA, ANCA, ACE)\: if vasculitic aetiology is suspected in younger patients
Myeloproliferative or sickle cell disease (blood
identi
younger patients
Other investigations
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
Echocardiogram\: to look for mural thrombus
Ambulatory ECG monitoring\: to look for paroxysmal atrial

Management

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.
Immediate management
If in temporal/giant cell arteritis,
then high dose steroids should be initiated immediately.
3
There are no o
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
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
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
Long-term management
Underlying risk factors should be addressed and modi
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\: o
Hypertension\: should be investigated and treated
Hyperlipidaemia\: a statin may be initiated
Atherosclerosis\: low-dose aspirin may be of bene
Atrial
risks outweigh the bene
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 noti
of vision in one eye. Patients may still be able to drive after clinical advice and successful adaptation to the condition.Complications
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
Prognosis
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
poor, although some improvement in visual acuity may be seen in the
or without treatment).
6

References

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]
Image references
Figure 1. Achim Fieß, Ömer Cal, Stephan Kehrein, Sven Halstenberg, Inezm Frisch, Ulrich Helmut Steinhorst. Adapted by
Geeky Medics. Cherry Red Spot Fiess. License\: [CC-BY].

Reviewer

Dr Byron Lu Morrell
Ophthalmology ST2

Acute Angle-Closure Glaucoma
Age-related Macular Degeneration (ARMD)
Amblyopia
Ametropia
Anisocoria

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