Summary

Acute angle-closure glaucoma (AACG) occurs when the anterior chamber angle is obstructed due to the iris bulging forward, preventing the drainage of aqueous humour. This can lead to an increase in intraocular pressure. It presents with severe eye pain, vision loss, headache, nausea and vomiting. Delay in treatment of the acute condition can lead to permanent vision loss, thus AACG is an ophthalmic emergency.

Aetiology

Aqueous humour is produced by the ciliary epithelium in the posterior chamber of the eye. It passes through the pupil into the anterior chamber and drains in the anterior chamber angle, also known as the iridocorneal angle.

There are two main drainage pathways for aqueous humour:

• Canal of Schlemm: most of the aqueous humour drains via the trabecular meshwork into the canal of Schlemm.
• Uveoscleral pathway: a small portion of the aqueous humour drains via the ciliary musle into the suprachoroidal space and supraciliary space.

AACG occurs when the iris bulges forward and blocks the anterior chamber angle. This blocks the drainage of aqueous humour and results in a rapid rise in IOP. The mechanism for this is shown in the diagram below. The pathway for aqueous humour drainage (shown using the blue arrow) is blocked in AACG.

The risk factors for AACG glaucoma include:

• Age
• Ethnicity (people of Asian heritage are more commonly affected)
• Family history
• Gender (females are more commonly affected than males)
• Hyperopia

Clinical features

Symptoms of AACG include:

• Painful, red eye
• Blurred vision