aka Ophthalmology Befuddler 024
A 68 year-old man has presented to the emergency department.
You ask, “What’s wrong?”. He says, “Nothing”.
You ask, “Why are you here?”. He points at his wife and says, “she made me come.”
You ask, “Why did your wife make you come to the emergency department?”. He says, “Well, for a couple of minutes there I couldn’t see out of my right eye, it’s better now though.”
You look at the chart and note the past history of hypertension, coronary artery disease, diet-controlled type 2 diabetes mellitus and the fact that he is a reformed smoker. He has never had migraines or giant cell arteritis and his eyes were open at the time of the transient monocular visual loss…
Questions
Q1. What is the likely diagnosis, and what are the differentials?
Amaurosis fugax — a transient ischemic attack affecting the retina.
Common causes of non-traumatic transient visual loss include:
- amaurosis fugax (usually minutes) — usually embolic or thrombotic; can occur secondary to hypoperfusion states, hyperviscosity or vasospasm.
- migraine (can be without headache)
- one eye closed!
Uncommon causes include:
- papilloedema (may be associated with visual loss lasting seconds)
- other causes of ischemic optic neuropathy, e.g. giant cell arteritis
- impending central retinal vein occlusion
- glaucoma
- posterior reversible encephalopathy syndrome (PRES)
- large vessel occlusion or dissection, e.g. ocular ischemic syndrome (carotid occlusive disease), vertebrobasilar insufficiency, and carotid or vertebral artery dissection
- functional visual loss, e.g. hysteria, malingering
Q2. What features should be assessed on history and examination?
History
- Classically there is transient monocular vision loss lasting seconds to minutes, but sometimes up to hours, with a return to normal vision. This may be experienced as a curtain coming down, blurring or fogging.
- There may have been previous episodes.
- Assess for cardiovascular/ stroke risk factors.
Examination
- Visual acuity and visual fields — normal following resolution of the attack; sectorial or complete monocular visual field loss during the attack.
- Full ophthalmic exam is generally normal — an embolus is rarely seen in a retinal artery.
- Cardiovascular and neurological exam — assess for cardiovacular disease and evidence of cerebral ischemia.
Q3. What investigations are required?
Essentially a TIA work up, which may include:
- Bedside — BSL, ECG
- Laboratory — FBC, UEC, lipid profile, fasting glucose, HbA1c
- Imaging — Echocardiogram, carotid doppler ultrasound, CT/MRI brain
Q4. What is the management of this condition?
- Refer to neurology +/- cardiology/ vascular surgery depending on the work up.
- Start aspirin.
- Recurrent amaurosis fugax may require early investigation and intervention.
- Treat underlying causes and risk factors.
Q5. What is ocular ischemic syndrome?
A condition caused by carotid artery occlusion (>90%), or rarely ophthalmic artery disease, that may underlie amaurosis fugax.
- It typically presents with ocular or periorbital pain and afterimages or prolonged recovery of vision after exposure to bright light. Symptoms may mimic central retinal artery occulsion (CRAO).
- The signs mimic central retinal vein occulsion (CRVO) with widespread hemorrhages and neovascularisation.
- Treatment usually includes carotid endarterectomy and photocoagulation.
References
- Ehlers JP, Shah CP, Fenton GL, and Hoskins EN. The Wills Eye Manual: Office and Emergency Room Diagnosis and Treatment of Eye Disease (5th edition). Lippincott Williams & Wilkins, 2008.
- Jeff Mann EM Guidemaps. Loss of vision.
- Marx JA, Hockberger R, Walls RM. Rosen’s Emergency Medicine: Concepts and Clinical Practice, 7th edition (2009) Mosby, Inc. [mdconsult.com]
- NSW Statewide Opthalmology Service. Eye Emergency Manual — An illustrated Guide, 2007. [link to free pdf]
About Chris Nickson
