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Acute Angle-Closure Glaucoma

Table of Contents

  • Key Points ⚡
  • Introduction
  • Aetiology & Anatomy
  • Pathophysiology
  • Risk Factors
  • Clinical Features
  • Investigations
  • Management
  • Complications
  • References
  • Related Notes
  • Test Yourself

Key Points ⚡

  • Acute angle-closure glaucoma (AACG): rapid increase in intraocular pressure (IOP) caused by narrowing of the anterior chamber angle → optic nerve damage and potential sight loss.
  • Incidence: ~2/100,000 per year (UK).
  • Aetiology: impaired aqueous humour drainage due to irido-trabecular contact; anatomical predisposition (short eyeball, hypermetropia).
  • Risk factors: older age, female sex, East Asian ethnicity, family history, pupil mid-dilation (darkness or medications).
  • Triggers: anticholinergics, antidepressants, pupil-dilating eye drops, topiramate.
  • Clinical features: unilateral severe eye pain, headache, nausea/vomiting, visual loss, rainbow-colored halos, red and hard eye, hazy cornea, mid-dilated pupil.
  • Investigations: gonioscopy (gold standard), tonometry (Goldmann applanation, iCare, Tono-Pen®).
  • Management: emergency—oral analgesics, antiemetics, laying patient flat, systemic acetazolamide, topical pressure-lowering agents, topical steroids, laser peripheral iridotomy.
  • Complications: permanent sight loss, retinal vein occlusion, recurrent AACG episodes.

Introduction

AACG is characterized by an acute rise in intraocular pressure due to narrowing of the anterior chamber angle (between iris and cornea), which impairs aqueous humour drainage, risking optic nerve damage and vision loss.

Aetiology & Anatomy

  • Aqueous humour is produced by the ciliary body, flows through the pupil into the anterior chamber, and drains via the trabecular meshwork and Schlemm canal.
  • Normal IOP ranges between 11–21 mmHg.
  • Angle closure occurs when irido-trabecular contact impedes aqueous outflow, causing pressure build-up.

Pathophysiology

  • Anatomically predisposed individuals (shorter axial eye length, shallow anterior chamber) are at risk.
  • Pupillary block mechanism: mid-dilated pupil causes contact between iris and lens, bowing peripheral iris forward to block drainage angle, causing rapid IOP rise.

Risk Factors

  • Age (60s–70s)
  • Female sex (3x risk vs. men)
  • East Asian ethnicity
  • Family history
  • Anatomical traits: short eyeball length, hypermetropia
  • Pupil mid-dilation triggers: dark environments, medications (anticholinergics like oxybutynin, antidepressants - SSRIs/TCAs, tropicamide eye drops), topiramate (bilateral AACG reported).

Clinical Features

History

  • Symptoms develop over hours to days.
  • May have been in dark room or taken triggering medications.
  • Severe unilateral eye pain or headache often with nausea/vomiting.
  • Visual loss, rainbow-colored haloes around lights.

Examination

  • Red eye with conjunctival injection.
  • Hard eye on palpation.
  • Corneal edema causing hazy appearance.
  • Mid-dilated, fixed pupil.
  • IOP usually >30 mmHg, can be as high as 60–80 mmHg.

Investigations

  • Gonioscopy: gold standard for assessing anterior chamber angle; confirms angle closure.
  • Tonometry: Goldmann applanation preferred; iCare and Tono-Pen® are portable and user-friendly; measures elevated IOP.

Management

  • Ophthalmic emergency; prompt treatment required to prevent vision loss.
  • Initial non-specialist measures: oral analgesics, antiemetics, lay patient flat.
  • Specialist treatment:
  • Systemic carbonic anhydrase inhibitors (acetazolamide IV or oral).
  • Topical pressure-lowering agents (beta-blockers, alpha agonists).
  • Topical steroids to reduce inflammation.
  • Laser peripheral iridotomy to create alternative aqueous outflow route.
  • Use of pilocarpine is nuanced; may aggravate some AACG types and is not universally recommended.

Complications

  • Permanent sight loss.
  • Central or branch retinal vein occlusion.
  • Recurrent episodes of AACG.

References

  • Royal College of Ophthalmologists. The Management Of Angle-Closure Glaucoma. [LINK]
  • He M, Jiang Y, Huang S, et al. Laser peripheral iridotomy for the prevention of angle closure: RCT. Lancet. 2019.
  • Salmon JF. Kanski’s Clinical Ophthalmology, 9th ed. Elsevier; 2019.
  • Jonathan Trobe. Acute Angle Closure Glaucoma. [CC BY]
  • Mick Lucas. Gonioscopy. [CC BY]
  • Age-related Macular Degeneration (ARMD)
  • Amblyopia
  • Ametropia
  • Anisocoria
  • Anterior Uveitis (Iritis)

Test Yourself

  • [Link to quiz or flashcards on Acute Angle-Closure Glaucoma]

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