Primary Angle-Closure Glaucoma

PACG Basics - Eye Under Pressure

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Mechanisms & Stages - The Closure Story

• Mechanisms:
  • Pupillary Block (>90%): Relative (lens-iris apposition) or absolute (posterior synechiae) → iris bombé → iridotrabecular contact (ITC).
  • Plateau Iris: Anterior ciliary processes push peripheral iris into angle. "Double hump sign".
  • Lens-induced: Phacomorphic, subluxation.
  • Malignant Glaucoma: Posterior aqueous misdirection.
• Stages (ISGEO Classification):
  • PACS: ≥180° ITC; normal IOP, no PAS, no optic disc damage.
  • PAC: PACS criteria + (PAS or ↑IOP); no glaucomatous optic neuropathy (GON).

    ⭐ Pupillary block is the predominant mechanism in over 90% of Primary Angle Closure cases.

  • PACG: PAC criteria + GON.
  • Acute Angle Closure Crisis (AACG): Sudden, severe IOP ↑; pain, blurred vision (corneal edema), halos, nausea.

Symptoms & Signs - Spotting the Attack

• Acute Angle-Closure Crisis (Ophthalmic Emergency):
  • Symptoms:
    • Sudden, severe unilateral ocular pain, may radiate.
    • Blurred vision ("steamy"), halos around lights.
    • Nausea, vomiting (oculocardiac reflex).
    • Headache, photophobia.
  • Signs:
    • IOP markedly ↑ (often > 40-50 mmHg).
    • Ciliary flush (circumcorneal injection).
    • Corneal edema (hazy cornea).
    • Shallow anterior chamber (AC).
    • Pupil: mid-dilated, fixed or sluggishly reactive, often vertically oval.
    • Gonioscopy: Confirms closed angle (e.g., Shaffer Grade 0).
• Intermittent (Subacute) Angle Closure:
  • Transient blurred vision, halos (e.g., in dim light, movies).
  • Mild eye ache or frontal headache.
  • Symptoms resolve spontaneously (e.g., sleep, bright light).

⭐ The classic triad of acute angle-closure crisis includes severe ocular pain, blurred vision with halos around lights, and nausea/vomiting.

Diagnosis & Management - Opening the Gates

• Diagnosis:

  • Gonioscopy: Gold standard (ITC, PAS).
  • UBM/AS-OCT: Angle/ciliary body imaging.

• Management Goal: ↓IOP, open angle, prevent ON damage.

• Acute Attack:

  • Medical:
    • Topical: Timolol 0.5%, Apraclonidine 1%, Pilocarpine 2% (post-IOP drop).
    • Systemic: Acetazolamide 500mg, Mannitol 1-2 g/kg IV.
  • Laser:

    ⭐ Laser Peripheral Iridotomy (LPI) is the definitive first-line treatment for eyes with pupillary block mechanism in PAC Suspect, PAC, and PACG.

  • Acute Management Steps:

• Chronic/Post-LPI:

  • Topical IOP-lowering meds.
  • ALPI (plateau iris).
  • Lens extraction/Trabeculectomy (if needed).

High‑Yield Points - ⚡ Biggest Takeaways

• Pupillary block is the most common mechanism in PACG.
• Risk factors: hypermetropia, female, older age, Asian ethnicity.
• Acute attack: sudden painful red eye, halos, nausea, mid-dilated fixed pupil, ↑↑IOP.
• Gonioscopy confirms occludable angles, essential for diagnosis.
• Acute treatment: Medical (IV mannitol, acetazolamide, pilocarpine) then Laser Peripheral Iridotomy (LPI).
• LPI is the definitive treatment for pupillary block PACG.
• Chronic PACG is often asymptomatic with progressive optic nerve damage.