Makindo Medical Notes

Acute Angle Closure Glaucoma (AACG) is a true ophthalmic emergency 🚨. A sudden rise in intraocular pressure (IOP) causes severe ocular pain, visual loss, and systemic upset. If untreated, optic nerve damage and permanent blindness may occur within hours to days.

📖 About

• Caused by pupillary block in predisposed eyes with shallow anterior chambers → iris bows forward → blocks aqueous outflow.
• Often triggered by pupillary dilation (dim light 🌙, stress, drugs such as anticholinergics or sympathomimetics).
• Rare after cataract surgery (lens removal deepens the chamber).
• “Golf ball hardness” globe on palpation = classic bedside clue.
• More common in older females (narrower anterior chambers).

🧬 Aetiology & Pathophysiology

• Pupillary block: aqueous humour cannot pass through pupil → pressure gradient pushes iris forward → trabecular meshwork blocked → IOP rises.
• Precipitating factors:
  • Dim light → physiological mydriasis.
  • Drugs: anticholinergics (atropine, tricyclics), sympathomimetics (decongestants), topiramate.
  • Emotional stress.
• Prolonged high IOP → ischaemic optic neuropathy → irreversible vision loss.

📊 Epidemiology

• Incidence: ~1 in 1,000 White, 1 in 100 Asian, up to 4 in 100 Inuit populations.
• Age: typically >60 years.
• Sex: female > male (~4:1).
• Risk factors: hyperopia, family history, shallow anterior chamber (short axial length).

🩺 Clinical Features

• ⚡ Sudden severe ocular pain + headache.
• 🌈 Blurred vision, halos around lights.
• 👁️ Red eye with mid-dilated, fixed pupil.
• 🥴 Nausea, vomiting, systemic upset (can mimic GI pathology).
• 🌫️ Corneal edema (“steamy cornea”).
• IOP usually >40 mmHg (normal 10–21).

🔎 Differential Diagnosis of a Painful Red Eye

🧪 Investigations

• Tonometry: IOP usually >40–70 mmHg.
• Slit-lamp: Corneal edema, shallow chamber, fixed pupil.
• Gonioscopy: Closed anterior chamber angle.
• Visual fields: For long-term glaucomatous damage monitoring.

🚑 Stepwise Management

1. Immediate (ED/GP setting)
   • IV Acetazolamide 500 mg stat (carbonic anhydrase inhibitor).
   • Topical Timolol 0.5% (beta-blocker) – reduces aqueous production.
   • Analgesia + antiemetics for distress.
   • O₂ if hypoxic.
2. Next (once IOP begins to fall)
   • Pilocarpine 2% drops – miotic → pulls iris away from angle.
   • IV Mannitol 20% if refractory to initial measures.
3. Definitive
   • Laser peripheral iridotomy (LPI) in affected + fellow eye (prophylaxis).
   • Surgical iridectomy if LPI unavailable.

🧾 Clinical Pearls

• Any elderly patient with sudden red eye + vomiting → assume AACG until proven otherwise.
• Never dilate pupils if AACG is suspected ❌.
• Fellow eye must always be treated prophylactically with iridotomy.
• Digital palpation: AACG feels like a “rock-hard” eye 🎾.

🖼️ Key Illustrations

💡 Teaching Pearl: AACG is one of the few causes of a painful red eye with systemic upset. Always compare to anterior uveitis (small irregular pupil) and keratitis (corneal ulcer in contact lens wearers). Rapid recognition + immediate acetazolamide + ophthalmology referral = sight-saving intervention.