Acute Angle Closure Glaucoma: Symptoms, Urgency And Treatment

Glaucoma is a group of eye conditions that can cause blindness by damaging the optic nerve, usually due to high eye pressure. Among its types, acute angle-closure glaucoma stands out for its rapid onset and the immediate need for medical intervention it demands.

Unlike the more common open-angle forms, which develop silently over years, an acute attack can threaten sight within hours. This page explains the warning signs, what to do if you have them, and how the condition is treated.

What is Acute Angle Closure Glaucoma?

Acute angle closure glaucoma is a severe form of glaucoma characterised by a sudden increase in intraocular pressure (IOP) when the drainage angle of the eye, formed by the cornea and the iris, becomes completely blocked. Unlike primary open-angle glaucoma, which progresses slowly, acute angle closure can occur suddenly, leading to rapid vision loss if not treated immediately.

How acute angle closure differs from other forms

Angle closure glaucoma can be primary, arising from the eye’s own anatomy, or secondary to another condition such as a cataract, eye tumour or uveitis. It can also be acute, developing within hours, or chronic, developing slowly and often without symptoms.

This page covers the acute form. For an overview of how all the forms of glaucoma compare, including the chronic angle-closure and open-angle types, see our guide to the types of glaucoma. You can also compare the two main mechanisms directly in our guide to open-angle versus closed-angle glaucoma.

Symptoms of an acute attack

An acute attack of angle-closure glaucoma is a medical emergency characterised by a sudden onset of symptoms, including:

• Severe eye pain: often described as intense, painful pressure within the eye.
• Blurred vision: a sudden decrease in visual clarity, which may be accompanied by halos around lights.
• Headache: a severe headache that often accompanies the eye pain.
• Nausea and vomiting: due to the severe pain and increase in intraocular pressure. This is sometimes mistaken for a stomach upset, which delays treatment.
• Eye redness: the eye may appear red and inflamed.
• Sudden vision loss: in severe cases, rapid vision loss can occur if the condition is not treated promptly.

Symptoms usually affect one eye and often begin in the evening or in dim lighting, when the pupil naturally widens and can crowd the drainage angle.

Who is most at risk

The risk factors for angle closure are largely anatomical. Understanding them matters because people at higher risk can often be treated preventively before an attack ever happens.

• Anatomical factors: a shallow anterior chamber, a narrow angle between the iris and the cornea, a thicker or more forward-sitting lens, and a shorter eye. These features make the drainage angle more likely to become blocked.
• Long-sightedness (hyperopia): long-sighted eyes tend to be shorter with shallower anterior chambers, narrowing the angle.
• Age: most commonly diagnosed after the age of 40. The lens continues to grow throughout life, gradually narrowing the angle.
• Ethnicity: people of East Asian and South Asian descent have a higher prevalence of angle-closure glaucoma, as do Inuit populations, due to differences in eye structure.
• Sex: women are more likely to develop angle-closure glaucoma, generally having shallower anterior chambers than men.
• Family history: a hereditary predisposition heightens the likelihood, particularly because the anatomical features that cause angle closure run in families.
• Cataract: as a lens becomes cloudy and enlarges, it can push the iris forward and narrow the drainage angle.
• Pupillary block: when fluid movement from the back to the front chamber of the eye is obstructed, pressure builds behind the iris and bows it forward, narrowing the angle. This is the mechanism behind most acute attacks.

How it is diagnosed

Diagnosis is made on examination, and in an acute attack it happens alongside emergency treatment rather than before it.

• Gonioscopy: the definitive test. Using a special contact lens with a mirror, the ophthalmologist views the angle between the iris and cornea to determine whether it is open or closed.
• Tonometry: measures intraocular pressure. Applanation tonometry, which applies gentle pressure through a pressure-sensitive tip, is the standard method. Pressure during an acute attack is often dramatically elevated.
• Anterior segment OCT: imaging that gives a detailed cross-section of the drainage angle, useful for assessing risk in the unaffected eye.
• Ophthalmoscopy: assesses the optic nerve for signs of damage.

Our guide to eye tests for glaucoma explains what each of these tests involves.

Immediate management of an acute attack

An acute angle closure attack is a medical emergency requiring prompt treatment to lower intraocular pressure and prevent permanent vision loss.

Medical treatment

Initially, medication is administered to rapidly decrease IOP. These may include:

• Oral or intravenous hyperosmotic agents: these help to lower IOP quickly by drawing fluid out of the eye.
• Topical beta-blockers, alpha agonists and prostaglandin analogues: these eye drops reduce IOP by either decreasing aqueous humour production or increasing its outflow.
• Acetazolamide: an oral carbonic anhydrase inhibitor that reduces the production of aqueous humour, thus lowering IOP.

Laser peripheral iridotomy (LPI)

Following initial medical management, LPI is often performed. This laser procedure creates a small hole in the peripheral iris, allowing aqueous humour to flow from the posterior to the anterior chamber, bypassing the block at the pupil. LPI can effectively prevent further acute attacks and is also used prophylactically in the fellow eye, which is at high risk of angle closure.

After an attack: what happens next

Once pressure has been brought down and the angle reopened, ongoing care depends on how much optic nerve damage occurred and whether the angle remains at risk of closing again. The fellow eye is usually treated preventively, since the same anatomy is present in both eyes.

Some people go on to need long-term pressure control, either with drops or with a further procedure such as cataract surgery, which deepens the anterior chamber by removing the enlarged lens. Our guide to glaucoma treatment in Australia covers the longer-term options in detail.

Preventing an attack

Not every case of angle closure can be prevented, because the underlying cause is anatomical. However, people at risk can often be identified before an attack occurs, and treated preventively.

Prophylactic laser peripheral iridotomy

For individuals identified as being at high risk for angle closure, such as those with narrow angles detected during an eye examination, prophylactic LPI may be recommended. By creating a small hole in the iris, LPI provides an alternative pathway for aqueous humour to flow, reducing the risk of angle closure. This preventive measure has been shown to significantly decrease the chance of an acute angle closure event.

Knowing your risk

Narrow angles are found during a routine eye examination, usually before any symptoms appear. If you are over 40, long-sighted, have a family history of glaucoma, or are of Asian or Inuit descent, mention it at your next eye test so the angle can be assessed. For broader risk reduction across all forms of glaucoma, see our guide to preventing glaucoma.

Frequently asked questions

How quickly does acute angle closure glaucoma cause damage?

Optic nerve damage can begin within hours of an attack starting. This is why acute angle closure is treated as an emergency: the difference between treatment on the same day and treatment days later can be the difference between preserved and permanently lost vision.

Can acute angle closure glaucoma happen in both eyes?

An attack usually affects one eye at a time, but the anatomy that caused it is normally present in both. This is why the unaffected eye is often treated preventively with laser peripheral iridotomy after an attack in the first eye.

Can medications trigger an attack?

Some medications that widen the pupil can precipitate an attack in an eye with an already narrow angle. If you have been told you have narrow angles, mention it to your doctor or pharmacist before starting a new medication.

Is vision lost during an attack recoverable?

Vision affected by the pressure itself, such as blurring from corneal swelling, usually improves once pressure is lowered. Damage to the optic nerve is permanent, which is why the speed of treatment matters so much.

Get assessed

If you have symptoms of an acute attack, seek emergency care now rather than booking an appointment. If you have been told you have narrow angles, have a family history of glaucoma, or are simply due for a check, our glaucoma specialists can assess your drainage angle and discuss whether preventive treatment is appropriate.

Contact Mornington Peninsula Eye Clinic on (03) 9070 3580 to book an appointment.

Note: Any surgical or invasive procedure carries risks. Before proceeding, you should seek a second opinion from an appropriately qualified health practitioner.

References 

1. https://www.healthline.com/health/closed-angle-glaucoma
2. https://emedicine.medscape.com/article/1206956-overview?form=fpf