Primary angle closure
At a glance
An occluded drainage angle may produce acute pressure elevation or chronic damage. Acute symptomatic closure is an emergency.
CAVE
- Do not dismiss the presentation as migraine or gastrointestinal illness.
- Consider bilateral drug-induced angle closure.
Clinical presentation
- Painful red eye, blurred vision, haloes, headache, nausea, corneal oedema and a poorly reactive pupil.
| Finding | Action | Timing / detail |
|---|---|---|
| PACS: ≥180° iridotrabecular contact on gonioscopy, normal IOP, no PAS or optic nerve damage | Assess anatomy and additional risk before preventive LPI | Not every narrow angle requires treatment |
| PAC: ≥180° contact with raised IOP and/or PAS, without glaucomatous neuropathy | Address the mechanism and pressure | PAS = peripheral anterior synechiae |
| PACG: angle closure with glaucomatous damage | Relieve closure and establish a long-term target IOP | LPI alone may not control the glaucoma |
Diagnosis & investigations
- Measure acuity and IOP in both eyes; examine pupil, corneal oedema, anterior chamber depth and lens. Perform gonioscopy when feasible and assess the fellow angle.
- Ask about recent dilation, anticholinergics, topiramate and prior attacks. Bilateral shallowing with an acute myopic shift suggests ciliochoroidal effusion rather than primary pupillary block.
Differential diagnosis
- Anterior uveitis, keratitis, neovascular glaucoma and lens-related or drug-induced closure.
Treatment
- Treat the mechanism as well as the pressure. Provide analgesia, antiemetic treatment and topical anti-inflammatory treatment when indicated.
- After the acute episode, document residual angle closure, PAS, lens contribution and optic nerve damage. Consider lens extraction or further glaucoma treatment when LPI is insufficient. A phakic fellow eye with an occludable angle after primary pupillary-block attack needs prompt preventive assessment.
| Finding | Action | Timing / detail |
|---|---|---|
| Painful acute closure with raised IOP | Immediate ophthalmic treatment; topical aqueous suppressants and acetazolamide 500 mg IV once, if suitable | Check renal function, electrolytes, contraindications and previous severe sulfonamide reaction; do not delay specialist care |
| Topical pressure reduction | Timolol 0.5% and apraclonidine 1% are options in the cited NHS protocol | Avoid timolol in asthma, significant bradycardia or heart block; review alpha-agonist interactions |
| Pupillary block | Consider pilocarpine 2% after pressure begins to fall and iris perfusion recovers; arrange LPI when feasible | Do not use this sequence for topiramate-related effusion or lens-induced forward displacement |
| Inadequate response | Recheck IOP and cornea at about 1 hour; senior review for hyperosmotic therapy or procedural decompression | Mannitol requires cardiac, renal and fluid assessment; do not repeat treatment blindly |
Follow-up
- Continue acute observation until pressure and symptoms respond. After LPI check IOP, patency and inflammation; repeat gonioscopy after the eye settles. Continue structural and functional glaucoma surveillance if damage or persistent pressure elevation is present.
Risk factors & context
- A shallow anterior chamber and a crowded anterior segment increase risk.
- Establish whether pupillary block, lens factors or another mechanism is responsible.
Complications
- Optic nerve damage, peripheral anterior synechiae and persistent pressure elevation can remain after the attack resolves.
When to refer
- Immediate ophthalmic treatment for an acute attack.
- Do not postpone assessment for routine imaging.
References 2
- European Glaucoma Society · Terminology and Guidelines for Glaucoma ↗6th edition · 2025 · Clinical examination; classification; treatment principles
- NHS GGC · Acute Angle Closure (adult protocol) ↗Reviewed 27 October 2022 · Initial pressure reduction; contraindications; one-hour reassessment
European guidance. Drug availability and authorisations must be checked locally.