Acute glaucoma

Specialties > Ophthalmology

Background knowledge 🧠

Definition

Acute glaucoma, also known as acute angle-closure glaucoma, is an ophthalmic emergency characterised by a sudden increase in intraocular pressure (IOP) due to impaired drainage of aqueous humor.
This condition can lead to optic nerve damage and irreversible vision loss if not promptly treated.

Epidemiology

More common in older adults, especially those over 60 years of age.
Higher prevalence in females and individuals of Asian descent.
Relatively rare, accounting for less than 10% of all glaucoma cases in the UK.

Aetiology and Pathophysiology

Caused by blockage of the trabecular meshwork, usually due to narrowing or closure of the anterior chamber angle.
Risk factors include hyperopia (far-sightedness), family history of glaucoma, and use of mydriatic agents.
Pathophysiology involves increased resistance to aqueous humor outflow, leading to a rapid rise in IOP.
The elevated IOP can compress the optic nerve, leading to optic neuropathy.

Types

Primary Angle-Closure Glaucoma: Occurs without an identifiable secondary cause.
Secondary Angle-Closure Glaucoma: Caused by underlying conditions such as uveitis, lens abnormalities, or neovascularisation.

Clinical Features 🌡️

Symptoms

Severe ocular pain, often described as a deep, aching pain.
Sudden onset of blurred vision.
Halos around lights, especially in low-light conditions.
Headache, nausea, and vomiting due to elevated IOP.
Ocular redness and photophobia.

Signs

Marked conjunctival injection (red eye).
Corneal oedema leading to a hazy or cloudy cornea.
Mid-dilated, non-reactive pupil.
Shallow anterior chamber on slit-lamp examination.
Elevated intraocular pressure, typically above 40 mmHg.

Investigations 🧪

Tests

Measurement of intraocular pressure using tonometry (e.g., Goldmann applanation tonometry).
Gonioscopy to assess the anterior chamber angle.
Slit-lamp examination to check for corneal oedema, shallow anterior chamber, and iris abnormalities.
Optic nerve head assessment via fundoscopy.
Visual field testing (perimetry) may be conducted to assess any optic nerve damage.

Management 🥼

Initial Management

Immediate referral to an ophthalmologist is essential.
Initial medical therapy includes topical beta-blockers (e.g., timolol), alpha agonists (e.g., apraclonidine), and systemic carbonic anhydrase inhibitors (e.g., acetazolamide).
Miotics (e.g., pilocarpine) may be used to reduce IOP by constricting the pupil and opening the anterior chamber angle.
Hyperosmotic agents like oral glycerol or IV mannitol can be used in severe cases to rapidly lower IOP.

Definitive Management

Laser peripheral iridotomy is the treatment of choice for preventing recurrence by creating an opening in the iris to facilitate aqueous humor drainage.
In cases where laser iridotomy is not possible, surgical options such as trabeculectomy may be considered.
Treat any underlying causes in cases of secondary angle-closure glaucoma.

Complications

Permanent vision loss due to optic nerve damage.
Chronic angle-closure glaucoma may develop if acute episode is not fully resolved.
Cataract formation may be accelerated due to increased IOP.
Possible recurrence of angle-closure glaucoma in the other eye.

Prognosis

Good prognosis if treated promptly, with most patients retaining useful vision.
Delayed treatment can lead to irreversible optic nerve damage and significant visual impairment.
Long-term follow-up is required to monitor IOP and prevent recurrence.

Key Points

Acute angle-closure glaucoma is an ophthalmic emergency requiring immediate intervention.
Prompt treatment is essential to prevent permanent vision loss.
Laser peripheral iridotomy is the definitive treatment to prevent recurrence.
Patients with one affected eye are at higher risk of developing glaucoma in the other eye.

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