PassFinals
Eyes & Vision

Acute angle-closure glaucoma

A sudden obstruction of aqueous outflow causes a rapidly painful rise in intraocular pressure, producing a red eye with visual symptoms and vomiting that needs same-day ophthalmology treatment.

In a nutshell

Aqueous outflow suddenly closes in a predisposed eye, causing a painful red eye with a hazy cornea, haloes, visual loss, vomiting and a fixed mid-dilated pupil. This is an ophthalmic emergency: urgent pressure lowering is followed by definitive mechanism-specific treatment and fellow-eye prevention.

Classic presentation

An older or hypermetropic person develops sudden severe unilateral eye pain, headache, haloes, blurred vision and vomiting with a red eye, hazy cornea and fixed mid-dilated pupil.

Key points

  • The mechanism is usually pupillary block in a crowded eye: the iris closes the trabecular angle and aqueous cannot drain.
  • A painful red eye with visual disturbance, a hazy cornea and a fixed mid-dilated pupil is an emergency, not routine conjunctivitis.
  • Same-day ophthalmology care is required; do not delay transfer for a complete community investigation.
  • Pressure-lowering therapy is ophthalmology-led. Pilocarpine is deferred until IOP has fallen below 40 mmHg because the ischaemic sphincter may not respond above that level.
  • Laser peripheral iridotomy or another mechanism-specific definitive treatment is followed by urgent assessment and prevention in the fellow eye.
  • Secondary angle closure needs cause-specific treatment; not every red eye with a shallow chamber is routine primary pupillary block.

First-line investigation

Visual acuity, urgent IOP measurement and ophthalmic examination including slit lamp and gonioscopy; transfer must not be delayed by non-specialist testing.

Management

Treat as an ophthalmic emergency

  • Contact ophthalmology immediately and arrange same-day emergency assessment or admission. Do not delay transfer for a complete community work-up, and do not use a routine red-eye pathway.3,1,2
  • Provide comfort, analgesia and antiemetic treatment as appropriate, avoid unrequested mydriatic or anticholinergic medicines and follow the local transfer pathway while urgent specialist care is arranged.1,2

Confirm the emergency without delaying treatment

  • Record visual acuity and IOP and arrange slit-lamp and gonioscopic assessment. Typical findings are a hazy cornea, shallow chamber, fixed mid-dilated pupil and markedly raised IOP; atypical findings should raise a secondary-mechanism differential.1,4,2

Lower pressure under ophthalmology direction

  • Use the emergency ophthalmology protocol for topical aqueous-suppressing and pressure-lowering agents, systemic acetazolamide when suitable and hyperosmotic treatment if pressure remains uncontrolled; check renal, cardiovascular, allergy and interaction risks against current BNF advice.1,5,6,8
  • Add pilocarpine only after IOP has begun to fall; do not rely on it while IOP is above 40 mmHg because the ischaemic sphincter may not respond. Treat inflammation when indicated by ophthalmology.1,7

Break the mechanism definitively

  • Once the cornea and pressure allow, perform laser peripheral iridotomy or another mechanism-appropriate definitive procedure in the affected eye. Assess and treat the fellow eye according to its gonioscopic risk rather than assuming it is safe because it has no symptoms.1,3

Review secondary causes and future triggers

  • Consider lens-related, inflammatory, neovascular, drug-induced and other secondary mechanisms. Definitive treatment may require lens extraction, iridoplasty or another specialist intervention, not iridotomy alone.1,2

Protect vision after the attack

  • Continue ophthalmology follow-up with IOP, visual acuity, gonioscopy, optic-nerve assessment and visual fields when feasible. Safety-net recurrent pain, halos, redness or visual change as a further emergency.1,4,2

Exam traps

  • Vomiting does not exclude an eye emergency; headache, nausea and visual disturbance should prompt an eye examination.
  • A red eye with a fixed mid-dilated pupil and hazy cornea is not simple conjunctivitis.
  • Do not give pilocarpine as though it will work at very high pressure; defer it until IOP is below 40 mmHg under ophthalmology direction.
  • The fellow eye is not low risk simply because it is asymptomatic; the anatomical predisposition is often bilateral.
  • NICE NG81 is principally a chronic open-angle and ocular-hypertension guideline; acute angle closure follows the Royal College of Ophthalmologists emergency pathway.

Illustrations

Aqueous outflow pathway and pupillary blockDiagram of aqueous flowing from the ciliary body through the pupil to the trabecular meshwork, showing how a crowded or mid-dilated iris can close the iridocorneal angle.PassFinals · original
Red eye in acute angle-closure glaucomaClinical photograph of a painful red eye caused by acute angle-closure glaucoma.James Heilman, MD, Wikimedia Commons · CC-BY-SA-3.0
Hazy cornea and mid-dilated pupilAcute angle-closure glaucoma showing a cloudy cornea and a fixed, mid-dilated pupil.Jonathan Trobe, M.D, Wikimedia Commons · CC-BY-3.0

Key sources

  1. Royal College of Ophthalmologists, The Management of Angle-Closure Glaucoma full guideline (Clinical guideline, June 2022)Published 24 Jun 2022
  2. NICE CKS, Glaucoma
  3. Royal College of Ophthalmologists, Management of Angle Closure Glaucoma guideline recommendations (Clinical guideline, 24 June 2022)Published 24 Jun 2022
  4. NICE, Glaucoma: diagnosis and management (NG81)Published 1 Nov 2017 | Updated 26 Jan 2022
  5. BNF, Acetazolamide
  6. BNF, Apraclonidine
  7. BNF, Pilocarpine
  8. BNF, Timolol maleate

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.