Acute angle-closure glaucoma: emergency management
The case
A 68-year-old long-sighted woman of East Asian background presents to the emergency department with 6 hours of sudden severe left eye pain, headache, nausea and several episodes of vomiting. Her vision in that eye is 'foggy' with halos around lights. There is no trauma. She takes hydrochlorothiazide for hypertension. Left visual acuity is counting fingers at 1 metre; the conjunctiva is markedly injected, the cornea is cloudy with epithelial oedema, the pupil is mid-dilated and poorly reactive, and the anterior chamber is shallow. Goldmann tonometry records a left intraocular pressure of 52 mmHg (10–21 mmHg). She has no known sulfonamide allergy. What is the single best immediate management step in the emergency department?
Options
- AIntravenous acetazolamide and pressure-lowering drops, then laser peripheral iridotomy
- BReassure and review in 48 hours
- CTopical steroid plus atropine drops
- DTopical phenylephrine then discharge
- EDilate with tropicamide and refer
Think it through before you read on. Which single option is best, and why are the other four wrong?
Show the answer and explanation
Answer
A. Intravenous acetazolamide and pressure-lowering drops, then laser peripheral iridotomy
Why this is the right answer
This is acute primary angle-closure glaucoma, an emergency that can cause permanent blindness within hours. The pattern is unmistakable: severe pain, headache, vomiting, halos, a cloudy cornea, a fixed mid-dilated pupil, a shallow anterior chamber and very high intraocular pressure. Risk factors here are age, female sex, hypermetropia (a shorter eye with a crowded angle) and East Asian ancestry.
The mechanism is pupillary block. The iris touches the lens, aqueous cannot pass into the anterior chamber, and the peripheral iris is pushed forward to close the drainage angle. The pressure rises rapidly and damages the optic nerve.
Immediate treatment lowers the pressure with drugs from several classes at once: intravenous acetazolamide 500 mg to reduce aqueous production, plus topical timolol, a topical alpha-2 agonist (apraclonidine or brimonidine) and a topical steroid for inflammation. Once the pressure has fallen below about 40 mmHg, pilocarpine 2% drops constrict the pupil and pull the iris out of the angle; given earlier, the ischaemic sphincter cannot respond. Antiemetics and analgesia are given, and the patient lies supine. Therapeutic Guidelines (Eye) sets out this sequence.
Definitive treatment is laser peripheral iridotomy, which creates a hole in the iris so aqueous can bypass the pupil. It is done as soon as the cornea is clear enough, and the fellow eye is treated prophylactically because it shares the same anatomy.
Ophthalmology must be called immediately; this is not a condition to manage alone.
Why the other options are wrong
- B
Delay of 48 hours at an IOP of 52 mmHg would very likely cause permanent optic nerve damage.
- C
Atropine dilates the pupil and worsens the angle closure; steroids alone do not lower pressure.
- D
Phenylephrine is a mydriatic that deepens pupillary block, and discharge without pressure control is unsafe.
- E
Tropicamide dilates the pupil and is contraindicated in angle closure.
High-yield takeaway
Painful red eye with a fixed mid-dilated pupil and high IOP: acetazolamide and pressure drops now, pilocarpine once the pressure falls, then laser iridotomy in both eyes. Never dilate.
Reference: Therapeutic Guidelines: Eye, Acute angle-closure glaucoma (2023)
Common questions
Which eye drops must be avoided in angle closure?
Any drop that dilates the pupil: tropicamide, atropine, cyclopentolate and phenylephrine.
Why treat the other eye?
The fellow eye shares the same narrow anatomy and has a high risk of a later attack, so a prophylactic iridotomy is done.
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