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.