Acute Glaucoma

Definition/diagnostic criteria Acute glaucoma, more specifically termed acute angle-closure glaucoma, is characterised by a rapid increase in intraocular pressure (IOP) due to obstructed aqueous humour outflow, often resulting from a narrow anterior chamber angle. It can be defined as a closure of the anterior chamber angle, leading to abrupt IOP elevation, with potential optic nerve damage and visual impairment.

Epidemiology In the UK, acute glaucoma accounts for a small but significant portion of all glaucoma cases. It is estimated that about 10% of all glaucoma in the UK is angle-closure type, with acute episodes being less common but more dramatic in presentation. The condition predominantly affects older adults, with a higher prevalence in women and in individuals of Asian descent.

Diagnosis
Clinical features: The classic presentation includes a red, painful eye, often accompanied by blurred vision and haloes around lights. Systemic symptoms may include nausea and vomiting. On examination, the affected eye typically appears red, with a hazy cornea, mid-dilated non-reactive pupil and reduced visual acuity.

Investigations:

• Diagnosis is confirmed by measuring IOP, which is typically >21 mmHg, often >40 mmHg in acute cases.
• Gonioscopy is essential for confirming angle closure.
• Optical coherence tomography (OCT) and anterior segment imaging can assist in identifying anatomical risk factors.

Treatment Initial management focuses on rapidly lowering IOP.

• Medications such as topical beta-blockers (e.g., timolol), alpha agonists (e.g., apraclonidine), and topical and systemic carbonic anhydrase inhibitors (e.g., acetazolamide) are used to decrease aqueous humour production.
• Topical pilocarpine may be employed to induce miosis and open the angle.
• Oral or intravenous hyperosmotic agents (e.g., mannitol) can be used to reduce vitreous humour volume, further lowering IOP.

Definitive treatment involves creating an alternative pathway for aqueous humour drainage, typically achieved with laser or surgical peripheral iridotomy. This procedure is recommended for both affected and contralateral eyes.

Prognosis The prognosis of acute glaucoma depends on the timeliness of treatment. Rapid intervention can lead to good outcomes, but delayed treatment can result in irreversible optic nerve damage and permanent vision loss. Regular follow-up is crucial for monitoring IOP and assessing for any signs of glaucomatous damage.