Acute Angle-Closure Glaucoma

Risk factors

• Hyperopia (small anterior segment)
• Age >50
• Female sex
• Asian or Inuit ancestry
• Family history of angle closure
• Mature cataract (thickens lens, pushes iris forward)
• Pharmacologic mydriasis (anticholinergics, sympathomimetics, antihistamines, tricyclics, topiramate — idiosyncratic ciliary body swelling)
• Dim light (movie theater, evening) — pupil mid-dilated, maximizes iris-lens contact and iris bunching at angle

Pathophysiology

Pupillary block: in eyes with shallow anterior chamber and crowded angle, the iris contacts the anterior lens surface, blocking aqueous flow from posterior to anterior chamber. Aqueous accumulates posteriorly, bowing the iris forward (iris bombe) and pressing the peripheral iris against the trabecular meshwork. IOP rapidly rises (often >40-60 mmHg), causing optic nerve ischemia, corneal edema, and pain. Plateau iris (less common): anterior insertion of the ciliary body causes peripheral iris to crowd the angle without pupillary block.

Clinical presentation

Differential diagnosis

• Acute iritis (anterior uveitis) — Photophobia, ciliary flush, miotic pupil, cells/flare; IOP usually normal or low; topical cycloplegic + steroid
• Conjunctivitis — Diffuse injection, no pain, clear cornea, normal pupil and IOP
• Corneal abrasion / keratitis — Foreign body sensation, fluorescein uptake, clear pupil; topical antibiotic
• Migraine with aura — Headache + visual symptoms; eye exam normal; responsive to migraine therapy
• Endophthalmitis — Recent intraocular surgery or trauma, hypopyon, severe vision loss; emergent vitreous tap and inject
• Acute hypertensive crisis / aortic dissection — Systemic symptoms; nausea + headache can mimic; check BP and ocular exam
• Cluster headache — Unilateral periorbital pain, autonomic signs (lacrimation, miosis), normal IOP; oxygen + triptan

Diagnostic workup

Diagnostic algorithm

flowchart TD
  A[Acute eye pain + headache<br/>± nausea/vomiting] --> B[Check IOP + slit lamp]
  B --> C{IOP >30 mmHg +<br/>steamy cornea +<br/>mid-dilated pupil?}
  C -->|Yes| D[AACG — emergency]
  D --> E[Call ophthalmology]
  D --> F[Topical: timolol +<br/>apraclonidine + dorzolamide]
  D --> G[Acetazolamide 500 mg<br/>IV or PO]
  G --> H{IOP <40 mmHg?}
  H -->|Yes| I[Pilocarpine 1-2%<br/>q15 min × 2]
  H -->|No| J[Mannitol IV 1-2 g/kg<br/>or oral glycerol]
  I --> K[Definitive: laser<br/>peripheral iridotomy<br/>within 24-48 h]
  J --> K
  K --> L[Prophylactic LPI<br/>on fellow eye]
  C -->|No| M[Consider iritis,<br/>conjunctivitis,<br/>keratitis, migraine]

Treatment

Complications

• Permanent optic nerve damage and visual field loss within hours
• Central retinal artery or vein occlusion from sustained high IOP
• Glaukomflecken (anterior subcapsular lens opacities from ischemia)
• Iris atrophy with sphincter paralysis (fixed dilated pupil)
• Chronic angle-closure glaucoma with peripheral anterior synechiae
• Bilateral disease — fellow eye is at high risk; prophylactic LPI is standard

PANCE pearls

• Acute angle-closure glaucoma can present with nausea and headache and be misdiagnosed as GI illness or migraine — always check the eye and the pupil.
• Mid-dilated FIXED pupil + steamy cornea + IOP >40 mmHg = AACG until proven otherwise.
• Pilocarpine does not work when IOP is very high because the ischemic iris sphincter cannot constrict — lower IOP first with aqueous suppressants and hyperosmotics, then give pilocarpine.
• Topiramate and sulfa-derivative drugs can cause idiosyncratic bilateral angle closure from ciliary body swelling — stop the drug and treat medically; iridotomy is NOT effective in this mechanism.
• After medical control, definitive treatment is laser peripheral iridotomy (or lens extraction) — and the fellow eye almost always needs prophylactic iridotomy.

References

• AAO 2020 — American Academy of Ophthalmology. Primary Angle Closure Disease Preferred Practice Pattern. Ophthalmology 2021;128(1):P30-P70
• EAGLE Trial — Azuara-Blanco A et al. Effectiveness of early lens extraction for the treatment of primary angle-closure glaucoma (EAGLE): a randomised controlled trial. Lancet 2016;388(10052):1389-1397
• ZAP Trial — He M et al. Laser peripheral iridotomy for the prevention of angle closure: a single-centre, randomised controlled trial. Lancet 2019;393(10181):1609-1618