aka Ophthalmology Befuddler 026
A 52 year-old man presents with sudden onset loss of vision in his right eye. He has no other symptoms. His past medical history is notable for hypertension, hyperlipidemia and angina. His medications include aspirin, atenolol, and atorvastatin. He can barely detect hand movements with his right eye and has a relative afferent pupillary defect.
Fundoscopy shows this appearance:
Q1. What is the diagnosis?
Central retinal artery occlusion (CRAO)
The diagnosis must be suspected in any case of sudden painless loss of vision, and is clinched by the appearance of the retina (see Q2).
Q2. What features on history and examination should be looked for?
- sudden and painless loss of vision (seconds)
- Consider underlying causes: emboli, thrombosis, GCA, CTDs, hypercoagualtion, trauma, migraine, syphilis, sickle cell disease, Behcet’s.
- Visual acuity — markedly reduced e.g. <6/60
- Marcus-Gunn pupils (RAPD)
- Red reflex — abnormal and asymmetrical
- Fundoscopy — a pale retina with areas of cilioretinal sparing and a classic ‘cherry red spot’ in the macula (may be subtle). Arteriolar and venular narrowing and box-car appearance.
Q3. What is the investigation and management?
CRAO, like chemical injuries to the eyes, is a true ophthalmological emergency.
Urgent ophthalmology referral, and a physician to work up underlying causes.
Treatment is unproven but includes:
- immediate ocular massage
- anterior chamber paracentesis
- IOP reduction with acetazolamide (e.g. 500mg IV) or timolol (0.5% topical drops bd)
- Breathe into a paper bag (respiratory acidosis induces retinal vasodilation)
Q4. How does an opthalmic artery occlusion differ from this condition?
Ther is no cherry red spot and vision is reduced to light perception. The entire retina is whitened. The treatment is the same.
Now, consider an alternative scenario in which the patient only had partial visual field loss and you saw this on funduscopy:
Q5. What is the diagnosis in this case, and how does it differ from the first?
Branch retinal artery occlusion (BRAO)
There is no cherry red spot and there is only partial visual field loss. A segment of retina is whitened along the distribution of a branch retinal artery. The treatment is the same.
- 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]