Risk Factors for PACG

PACG shows distinct demographic and anatomical patterns. Risk factors include:

• Asian ethnicity (10-fold higher prevalence than Europeans)
• Female sex (female-to-male ratio approximately 3:1 to 4:1)
• Age over 50 years
• Hyperopia (short axial length)
• Shallow anterior chamber depth (<2.5 mm)
• Thick lens and increased lens vault
• Family history of glaucoma

Mechanisms of Angle Closure

Pupil block is the most common mechanism — aqueous trapped behind the iris creates a pressure gradient that bows the iris forward (iris bombé), progressively narrowing and eventually closing the angle. Other mechanisms include plateau iris (ciliary body mass pushing iris forward), secondary angle closure (neovascularisation, inflammation, lens swelling), and combined POAG with superimposed angle closure.

Acute Attack Management

Acute angle-closure is a medical emergency requiring immediate treatment to rapidly lower IOP and prevent permanent optic nerve damage:

Immediate Medications:

• Intravenous acetazolamide: 500 mg IV to reduce aqueous production
• Intravenous mannitol: 1–2 g/kg to shrink lens and deepen anterior chamber
• Topical timolol: 0.5% four times daily to reduce aqueous production
• Topical pilocarpine: 1% four times daily to constrict pupil (before pressure lowers)
• Topical steroids: prednisolone acetate 1% hourly to reduce inflammation

Definitive Treatment:

Once IOP is lowered and cornea clears, definitive treatment is required — laser peripheral iridotomy (LPI) to relieve pupil block, or clear lens extraction (CLE). The EAGLE trial (2016) demonstrated that CLE is superior to LPI for PAC and PACG, with better long-term IOP control and fewer additional interventions.