Acute angle closure and glaucoma

Acute angle closure is when your eye’s drainage system suddenly closes. It can be painful, and it can lead to a rapid rise in eye pressure. It can damage parts of your eye, including the cornea, lens, retina and optic nerve. This damage can lead to glaucoma (called angle closure glaucoma) and sight loss. If you think you might have acute angle closure, you should seek medical advice straight away. 

All these terms can get confusing. Often people refer to acute angle closure as acute angle closure glaucoma. But the term acute angle closure glaucoma is only correct if acute angle closure damages your optic nerve during the attack. When treated quickly, acute angle closure is unlikely to lead to glaucoma and sight loss. 

We have provided lots of information about this topic below, but if you still have questions, please don’t hesitate to reach out to our helpline team. 

What is angle closure? 

Angle closure is when your eye’s drainage system closes and stops fluid draining out of your eye. 

The front of your eye contains a watery fluid called aqueous humour, aqueous fluid or just aqueous. Aqueous helps your eye keep its shape and brings nutrients to the front of your eye. Aqueous is made inside your eye and drains out of your eye through tiny drainage channels, called the trabecular meshwork. 

The drainage channels are in the angle between your iris and your cornea, known as the drainage angle. Your iris is the coloured part of your eye, and your cornea is the clear window at the front of your eye. 

If your iris comes too far forward, it closes your drainage angle. Angle closure can happen suddenly, or slowly over weeks, months or years. If it happens suddenly, it’s called acute angle closure.  

When your drainage angle is closed, Aqueous cannot drain properly out of your eye, and the pressure inside your eye goes up. This pressure is called eye pressure or intraocular pressure (IOP). 

Acute angle closure causes a rapid rise in eye pressure. This can be painful and can damage your eye in a matter of hours. Prompt treatment reduces the risk of damage to important parts of your eye like the cornea, lens and retina, helping to prevent sight loss. 

What are the symptoms of acute angle closure? 

Symptoms of acute angle closure include: 

• Intense eye pain (usually in just one eye) 
• Headache 
• Feeling or being sick 
• Seeing coloured rings around lights 
• A red eye 
• Blurred, foggy or reduced vision 

Go to accident and emergency (A&E) or an emergency eye clinic straight away if you get symptoms of acute angle closure. 

You might have a series of short spells of sub-acute angle closure with mild symptoms. Your symptoms might disappear after a night’s sleep but then come back at some point. This is called intermittent angle closure. If you have intermittent angle closure, you may be at risk of more serious angle closure. 

What is angle closure glaucoma? 

Glaucoma is a group of common eye diseases where your optic nerve has become damaged. Your optic nerve connects your eye to your brain, so damage to this nerve affects your sight. Glaucoma is often linked to high eye pressure. 

Acute angle closure leads to high eye pressure, which sometimes leads to glaucoma. If your optic nerve is damaged during an episode of acute angle closure, it’s called acute angle closure glaucoma. But if you get treatment quickly, acute angle closure glaucoma is unlikely. Alternatively, acute angle closure can damage your eye’s drainage system, leading to long-term high eye pressure. If this long-term high eye pressure damages your optic nerve, it’s just called angle closure glaucoma. Again, rapid treatment makes this unlikely. 

• Acute angle closure is when your eye’s drainage channel suddenly closes leading to a rapid and often painful rise in eye pressure. It only sometimes leads to glaucoma. 
• Acute angle closure glaucoma is when your optic nerve gets damaged during an episode of acute angle closure. If you get treatment quickly, this is unlikely. 
• Angle closure glaucoma is when your eye’s drainage system closes, suddenly or slowly, leading to long-term high eye pressure that damages your optic nerve. 

Who gets acute angle closure? 

Some people are more likely to develop acute angle closure than others. It’s usually linked to having small eyes with less space inside the front of your eyes. You’re more likely to develop acute angle closure if, for example, you’re: 

• A woman 
• Aged over 40 years 
• Asian (especially Chinese) 
• From a family with a history of angle closure 
• Long sighted 

What causes acute angle closure? 

Anything that makes your pupil bigger pushes your iris forward and could cause acute angle closure. Your pupil is the black dot (a hole) in the middle of your iris. Lots of things make your pupil bigger, and most of the time they’re perfectly safe. Examples include: 

• Dilating eye drops (such as those used for diabetic eye examinations) 
• Dim lighting 
• Sudden excitement or adrenaline rushes 
• Some medicines (for example some anti-depressants—check the leaflet that comes with any medicines you take or talk to your pharmacist, GP or eye doctor) 

An injury to your eye can also cause angle closure. 

What treatments are there for acute angle closure and for angle closure glaucoma? 

Acute angle closure must be treated quickly to stop pain and prevent sight loss. Treatment aims to open the drainage angle, allowing aqueous to drain out of your eye, lowering eye pressure. Lowering eye pressure helps prevent future sight loss from glaucoma. 

A doctor will first give you eye drops to make your pupil smaller. This helps push your iris back and opens your drainage angle. The doctor might then give you: 

• Tablets, injections or eye drops to reduce the amount of aqueous your eye makes 
• Steroids to reduce swelling (inflammation) in your eye 

Once your eye pressure is low enough, an eye doctor can then give you laser treatment, surgery or even both. Laser treatments and surgery help lower eye pressure more and help prevent your drainage angle closing again in the future. 

The most common surgery for angle closure is lens extraction (“cataract surgery”). It’s the same surgery that’s used to treat cataracts (a cloudy lens), but it’s used to treat angle closure whether or not you have cataracts. Your eye’s lens helps adjust the focus of light onto the light-sensitive layer at the back of your eye. In lens extraction surgery, an eye doctor takes your natural lens out of your eye and puts in a thinner artificial lens. Because the artificial lens is thinner, there’s more space in your eye. The extra space helps your iris move back and opens your drainage angle. This surgery is usually fairly quick, generally safe and most people only get mild side effects.  

The most common laser treatment for acute angle closure is laser iridotomy. In laser iridotomy, an eye doctor uses a laser beam to make a small hole in your iris. Aqueous flows through this hole to the space in front of your iris and pushes your iris back, opening your drainage angle. This is an effective, quick and safe treatment, and most people only get mild side effects. 

If your eye pressure is still high after surgery or laser treatment, your eye doctor might prescribe eye drops to lower it. You’ll need to keep taking these until your eye doctor tells you to stop. 

If you are at high risk of angle closure, your eye doctor might offer you lens extraction surgery or laser iridotomy to prevent future angle closure. If you’ve had acute angle closure in one eye, you’re at higher risk of developing it in your other eye. To prevent future angle closure, your eye doctor will probably treat both your eyes. 

After acute angle closure, you’ll usually have regular eye clinic appointments. The eye doctor will check your eye pressure, eye health and sight. They’ll check how well any treatment is working and whether your treatment needs to change. 

Will I get sight loss? 

If you get treatment quickly for acute angle closure, you have a good chance of keeping good sight. The longer you delay or must wait for treatment, the more sight you’re likely to lose. Go to accident and emergency or an emergency eye clinic straight away if you have symptoms of acute angle closure. 

For more information, contact our helpline at helpline@glaucoma.uk or on 01233 64 81 70. 

Learn more about glaucoma here.

With thanks to: 

• Paul Foster, Professor of Ophthalmic Epidemiology and Glaucoma Studies, UCL Institute of Ophthalmology 
• M Heravi, Consultant ophthalmologist