Acute angle-closure glaucoma: a red painful eye emergency
Sight can be lost in hours
Dr. Camille Roux
Internal medicine physician
In simple terms
How drainage suddenly blocks, the classic symptoms, and why laser treatment protects the other eye too.
What it is, in plain words
Fluid produced inside the eye normally drains through a mesh in the angle between iris and cornea. If the iris suddenly blocks that angle, pressure rises steeply within hours, damaging the optic nerve. This is different from the common chronic open-angle glaucoma, which is painless and slow.
Signs to look out for
- Severe pain in one eye, often with headache on that side
- Rapidly blurred vision with rainbow halos around lights
- Red eye and a fixed, mid-dilated oval pupil
- Nausea and vomiting, which can lead to a wrong diagnosis of migraine or stomach illness
- Eye that feels hard to the touch
Why it happens
Risk is higher in long-sighted people with shallow anterior chambers, in older adults, in women, in people of East Asian descent, and after medicines that dilate the pupil, including some antidepressants, antihistamines, anticholinergics and travel sickness patches.
How doctors confirm it
Measuring intraocular pressure, which may exceed 40 mmHg, plus slit-lamp examination and gonioscopy of the angle, confirms it. Imaging assesses optic nerve damage later.
Treatments and solutions
- Immediate pressure-lowering drops and oral or intravenous medicines such as acetazolamide
- Pilocarpine drops to pull the iris away from the angle once pressure begins to fall
- Laser peripheral iridotomy, a tiny hole in the iris that restores flow and is the definitive treatment
- Prophylactic laser to the other eye, because it carries the same anatomy and risk
- Cataract surgery or drainage surgery in selected cases
Living with it day to day
If you have been told you have narrow angles, ask a pharmacist before taking any medicine labelled as contraindicated in glaucoma, and never ignore a painful red eye with blurred vision.
When to seek medical help
This is an emergency: go to an eye casualty or emergency department the same hour, not the next day.
This article explains general health information in simple language. It does not replace advice from your own doctor.
The words explained
Medical terms used above, in everyday language.
- Chronic
- A problem that lasts a long time, usually more than three months, and often comes back.
- Diagnosis
- The moment a doctor identifies which illness is causing your symptoms.
When should you see a doctor?
- Your symptoms last more than a few weeks or keep coming back.
- They get worse quickly, or stop you doing everyday things.
- You notice sudden pain, breathing trouble, fainting or bleeding — seek urgent care.
- You already take medication and want to change anything about it.
This article explains general health information. It does not replace advice from your own doctor.
Frequently asked questions
- What is Acute angle-closure glaucoma: a red painful eye emergency?
- How drainage suddenly blocks, the classic symptoms, and why laser treatment protects the other eye too.
- What are the main symptoms or signs of Acute angle-closure glaucoma: a red painful eye emergency?
- Common signs vary from person to person. The article above lists the symptoms to watch for, how they progress, and when they need medical attention.
- When should you see a doctor for Acute angle-closure glaucoma: a red painful eye emergency?
- See a doctor if symptoms last more than a few weeks, get worse quickly, stop you doing everyday things, or if you notice sudden pain, breathing trouble, fainting or bleeding.
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