Central Retinal Artery Occlusion

This is usually due to emboli arising in the carotid artery, intracranially or from the heart. A quarter of eyes have collateral arteries serving the macular retina so that central vision can be retained to some extent.

Incidence

Is a common cause of blindness in the elderly. Majority of patients are >60 years. Younger patients usually have valvular heart disease.

Risk factors

• Atrial fibrillation
• Aortic or mitral valve disease or prosthesis
• Endocarditis
• Atherosclerosis
• Thrombophilias
• Polyarteritis
• Syphilis
• SLE
• Giant cell arteritis
• Takayasu aortitis

Symptoms

• Painless, almost instantaneous loss of vision in one eye.
• In 90% of cases visual acuity ranges from counting fingers to light perception.
• May have been earlier transient visual loss (amaurosis fugax).

Signs

• Afferent pupillary defect can appear an hour before abnormality of the fundus, immediately after occlusion.
• Opacified superficial retina, except cherry-red spot in the foveola (choroid or retinal pigment epithelium seen through very thin overlying foveola retina).
• Retinal opacification resolves within 4-6 weeks leaving pale optic disc.

• Fluorescein angiography
• Carotid Doppler ultrasound to detect occlusion even in absence of bruit
• Investigate other risk factors for atherosclerosis.
• Optical Coherence Tomography. (This is an interferometric, non-invasive optical imaging technique first demonstrated in 1991. It produces a cross-sectional image of tissue.¹ Central retinal artery occlusion has a distinct pattern,² which may distinguish cases that are equivocal on clinical findings.

Non-drug

• Firm ocular massage may dislodge embolus, or contact lens may be used
• Anterior chamber paracentesis
• Isovolaemic haemodilution
• Reduction of arterial hypertension

Drug

• Acetazolamide, aspirin.
• Intra-arterial fibrinolysis; local injection of urokinase or recombinant tissue plasminogen activator into the proximal part of the ophthalmic artery.³ The EAGLE study is currently evaluating outcomes with this treatment versus conservative management.⁴

• Sight often remains poor despite treatment.⁵
• Other eye usually unaffected if risk factors treated.
• Patients with retinal emboli have a 3x increased mortality rate compared to those without.⁶ They should be managed in the same way as patients with a personal history of ischaemic heart disease.

Anticoagulants