|

Central Retinal Artery Occlusion

Last updated:

Overview

Central retinal artery occlusion (CRAO) is a cause of sudden and painless loss of vision. It is an ophthalmic emergency as retinal ischaemia can lead to permanent vision loss and patients must be treated immediately. It is often considered the eye equivalent of a stroke.

The retina is normally supplied by:

  • The central retinal artery:
    • A branch of the ophthalmic artery which emerges from the internal carotid artery
    • Supplies the optic disc and four quadrants of the inner retina
  • Choroidal capillaries that branch off the posterior ciliary arteries which emerge from the ophthalmic artery

Epidemiology

  • More commonly seen in older patients >60 years
  • Younger patients usually have predisposing heart diseases such as valvular disease
  • Men are slightly more affected than women

Causes and Risk Factors

Presentation

Patients have a sudden unilateral painless loss of vision. This is usually over a few seconds. Other features that may be seen are:

  • Severe loss of vision – this may be seeing hand movements or be as severe as seeing nothing at all
  • Amaurosis fugax – transient vision loss
    • Due to retinal ischaemia, but vision returns when blood flow is restored
    • Patients may have episodes of this preceding CRAO
    • This may be described as a ‘curtain coming down’
  • Relative afferent pupillary defect
  • Fundoscopy shows a pale retina with a “cherry red” spot

Differential Diagnoses

Central retinal vein occlusion

  • More common than CRAO
  • Difficult to distinguish clinically, they both present identically
  • Fundoscopy shows severe retinal haemorrhages

Vitreous haemorrhage

  • There may be a history of trauma of poorly-controlled diabetes
  • There may be vision haze or red colour to vision
  • Fundoscopy shows haemorrhages

Retinal detachment

  • Flashes of light and floaters followed by a “curtain” coming over the vision
  • Fundoscopy may show detachment

Stroke

  • Usually other associated neurological deficits are present e.g. weakness, facial or arm drooping, slurred speech etc

Investigations

Overview

  • Fundoscopy:
    • Usually shows pale retina and “cherry red spot”
  • Fluorescein angiography – if fundoscopy inconclusive
    • Shows absent filling of central retinal artery

Other investigations

Other investigations are considered to identify the cause:

  • Carotid artery ultrasound:
    • To screen for carotid artery stenosis
  • ESR and CRP:
    • Elevated in giant cell arteritis
  • ECG/Holter monitoring:
    • For arrhythmias such as atrial fibrillation
  • Echocardiogram:
    • For structural heart defects e.g. valvular pathology
  • Full blood count:
    • For haematological causes
  • Blood glucose:
    • For diabetes
  • Lipid profile:
    • For dyslipidaemia and cardiovascular risk
  • Coagulation studies:
    • For thrombophilias

Management

Overview

Patients must be referred immediately to ophthalmology. At the moment, there is no universal first-line option. Some options are:

  • Thrombolysis using urokinase
  • Ocular massage – only done within 90 minutes and may dislodge the obstruction
  • Reducing intraocular pressure – usually with anterior chamber paracentesis + acetazolamide
  • Vasodilator therapy – e.g. sublingual isosorbide dinitrate

Patient Advice

  • Patients should stop smoking, reduce alcohol intake, and maintain a healthy and balanced diet to reduce their cardiovascular risk
  • Patients should notify the DVLA about their condition. They may still be able to drive if they can clinically demonstrate they have adapted to the condition. 

Complications

Prognosis

  • The prognosis is generally very poor, even with early intervention. Only a third of patients show improvement.

Author