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Clinical Opal #5 - Red eye

17 September 2021 - Dr Simon Morgan

The eye has become increasingly painful and her vision is now very blurred. She has a ‘bad headache’ and feels like she is going to vomit. There is no history of trauma and she has never had anything like this before.  Fatima is usually well with no significant past medical history and is on no regular medications.  

On examination, Fatima is afebrile, BP 150/90 and HR 96. Examination of her left eye reveals conjunctival injection, a cloudy cornea, a mid-dilated pupil that is poorly responsive to light, photophobia and VA of 6/60.

What is the most likely cause for Fatima’s presentation, and what important differential diagnoses need to be considered?

Fatima’s presentation is typical for acute angle closure glaucoma, an ocular emergency characterised by severe,
rapid-onset raised intraocular pressure (IOP) resulting from failure of the trabecular drainage system. Precipitants include topical mydriatics, anticholinergic and sympathomimetic drugs, and prolonged accommodation (reading in dim light). Diagnosis is confirmed by tonometry and high IOP, and excluding other causes like CRVO. Acute angle closure glaucoma is an emergency presentation and requires urgent ophthalmology assessment. Management includes topical B-blockers and miotics, acetazolamide, and iridotomy.

Important differential diagnoses for the painful red eye are numerous, and include uveitis, keratitis (bacterial and HSV), corneal abrasion, trauma, scleritis, herpes zoster, orbital cellulitis, and endophthalmitis. Each has specific clinical features which can help with diagnosis, but a low threshold for referral is essential to reduce the risk of permanent visual loss.



  1. AFP 2008 Ocular emergencies
  2. Life in the Fast Lane Blind, aching and vomiting
  3. AFP 2016 More than meets the (painful red) eye

Dr Simon Morgan
Dr Simon Morgan

Simon is a GP based in Newcastle, NSW, and a senior medical educator with Medcast.  He also has medical education roles with the RACGP and GPSA.

Over the past three decades, Simon has worked in clinical and educational roles in NSW and the NT, as well as in the Republic of Ireland. He has published over 75 peer reviewed journal articles, and in 2018 received the RACGP Corliss award for his contribution to medical education.

Simon is passionate about high quality education and training. He has particular interests in GP supervisor professional development and the rational use of tests and medicines. He is a proud member of Doctors for the Environment. He spends his spare time drinking craft beer and pretending that he is a musician in the Euthymics, an all-GP band.

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