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Primary angle closure and acute angle-closure glaucoma
In primary angle closure the iris is pushed forward and blocks the drainage system — usually from pupillary block in a short, hyperopic eye — and in an acute attack pressure soars; treatment is immediate pressure lowering followed by laser peripheral iridotomy (LPI) in both eyes.
Why it matters in the exam
The classic exam picture: an older hyperopic woman presents in the evening after time in the dark or after dilating drops or an anticholinergic drug, with severe eye pain, headache, nausea and vomiting, blurred vision and haloes around lights. On examination: a red eye, an oedematous cornea, a shallow anterior chamber, a fixed mid-dilated pupil and very high pressure, sometimes above 50 mmHg. The vomiting sometimes misleads towards an acute abdomen.
The classification (ISGEO): primary angle closure suspect (PACS) — iridotrabecular contact without damage; primary angle closure (PAC) — peripheral anterior synechiae (PAS) or raised pressure without nerve damage; primary angle-closure glaucoma (PACG) — with optic neuropathy. Risk factors: age, female sex, East Asian ancestry, hyperopia and a thick lens. Gonioscopy with indentation separates appositional closure from permanent synechiae.
Treating the attack: topical beta-blocker, alpha-2 agonist and steroid, acetazolamide 500 mg orally or intravenously, and intravenous mannitol 1–2 g/kg when pressure is very high; pilocarpine 1–2% only after pressure has fallen, because the ischaemic sphincter does not respond. The definitive treatment is LPI, and in the fellow eye as prevention — without it about half of fellow eyes have an attack within 5 years. The EAGLE trial showed clear lens extraction to be better than LPI in PAC with pressure of 30 mmHg or more and in PACG.
Key points
- Pupillary block in a short, hyperopic eye with a thick lens.
- Pain, vomiting, haloes, fixed mid-dilated pupil, oedematous cornea.
- Medical pressure lowering, then LPI in both eyes.
- Topiramate causes bilateral closure without pupillary block.
- EAGLE: clear lens extraction is better in PACG.
Summary table
| Condition | Mechanism | Finding | Treatment |
|---|---|---|---|
| Acute attack | Pupillary block | Pain, vomiting, oedematous cornea, fixed mid-dilated pupil | Pressure-lowering drugs, then LPI in both eyes |
| Chronic closure | Gradual PAS | Painless high pressure, disc damage | LPI, drops, lens extraction |
| Plateau iris | Anteriorly rotated ciliary processes | Closed angle despite a patent LPI | Laser iridoplasty or lens extraction |
| Topiramate | Ciliochoroidal effusion | Bilateral closure and sudden myopia | Stop the drug, cycloplegia; not LPI |
| Phacomorphic | Mature swollen lens | Unilateral closure with a dense cataract | Lower pressure and remove the lens |
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Sources
- AAO Preferred Practice Pattern: Primary Angle Closure Disease, 2020 — Diagnosis and management
- European Glaucoma Society: Terminology and Guidelines for Glaucoma, 5th edition (2020) — Primary angle closure
- AAO Basic and Clinical Science Course, Section 10: Glaucoma, 2024-2025 — Angle-closure glaucoma
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.