Acute angle-closure glaucoma

Background

Pathophysiology

• Obstructed aqueous outflow tract > aqueous humor builds > increased intraocular pressure (IOP) > optic nerve damage > vision loss
• Increased posterior chamber pressure causes iris to bulge forward (iris bombé) > further obstruction of outflow tract > further increase IOP
• Acute attack is usually precipitated by pupillary dilation

Definition: 3 signs + 2 symptoms

• At least 3 of these signs:
  • IOP >21 mm Hg
  • Conjunctival injection
  • Corneal epithelial edema
  • Mid-dilated nonreactive pupil
  • Shallow anterior chamber with occlusion
• At least 2 of these symptoms:
  • Ocular pain
  • Nausea/vomiting
  • History of intermittent blurring of vision with halos

Clinical Features

• Abrupt onset of severe eye pain
• Blurred vision
• Frontal or supraorbital headache
• Nausea / vomiting / abdominal pain

Diagnosis

• Fixed, midposition pupil
• Hazy cornea
• Conjunctival injection most prominent at limbus (ciliary flush)
• Rock-hard globe
• IOP >20 mm Hg
• SLIT LAMP exam shows Cell and Flare which represents visualization of individual cells in the shallow anterior chamber

Treatment

• Emergent ophthalmology consult
• Decrease production of aqueous humor:

1. timolol 0.5% drop: blocks beta receptors on ciliary epithelium
2. apraclonidine 1% drop: alpha-2 adrenergic receptor agonist which increases trabecular outflow
3. acetazolamide 500mg IV or PO: blocks productions of HCO3-, which draws Na+ into the eye; water follows by osmosis to form aqueous humour

• Facilitate outflow of aqueous humor:

1. pilocarpine 1%–2% drop: parasympatholytic alkaloid acts on muscarinic receptors found on iris sphincter muscle ==> causes muscle to contract ==> miosis
   1. In USA - green top
   2. Use one drop every 15 minutes x 2 doses, then every 4 to 6 hours
   3. Only effective when IOP <40 mm Hg

• Reduce volume of aqueous humor:

1. mannitol 1–2gm/kg IV: if no contraindications

• Recheck IOP hourly

See Also

• Eye Algorithm (Main)

Source

Tintinalli