Acute angle-closure glaucoma: a case-based approach

The presentation

Imagine an adult, often older, who develops a sudden, severe pain in one eye, sometimes spreading to the forehead and the side of the head. The eye is red, the vision becomes blurred quite quickly, and they see coloured rings or halos around lights, especially in dim surroundings such as a cinema. The eye may feel hard, the pupil can look mid-sized and fixed, and the pain is often so intense that it brings on nausea and vomiting and a feeling of being generally very unwell. Sometimes the headache and vomiting are so prominent that the eye itself is overlooked. This combination — a sudden painful red eye, fast-blurring vision, halos around lights, and feeling sick — is the hallmark of acute angle-closure glaucoma and must be acted on straight away.

Why it threatens sight so quickly

The eye constantly makes a clear fluid that normally drains away through a tiny channel at the angle where the coloured iris meets the clear front window of the eye. In some eyes this angle is naturally narrow. If it suddenly closes off, fluid can no longer escape, so pressure inside the eye rises very fast — far higher than normal. This high pressure squeezes the delicate optic nerve at the back of the eye, the nerve that carries pictures to the brain, and can damage it within hours. That is why sight can be lost so rapidly and why the condition is a genuine emergency: the longer the pressure stays very high, the more permanent the damage. Prompt hospital treatment to lower the pressure aims to save the sight.

When to seek emergency help

A sudden painful red eye with blurred or reduced vision, halos around lights, a hard eye, or vomiting is a same-day eye emergency. Contact NHS 111, your nearest eye casualty or emergency eye service, or go to A&E without delay — this cannot wait for a routine optician or GP appointment. If you cannot reach an eye service quickly, or the person is very unwell or in severe pain, call 999 or go to A&E. Do not put off getting seen in the hope it settles, and do not simply take painkillers and go to bed, because every hour of very high pressure risks permanent sight loss. Tell whoever you speak to that you are worried about sudden loss of vision with a painful red eye, so it is treated as the emergency it is.

Who is more at risk

Some people are more prone to angle-closure because of the natural shape of their eye — for example those with a shallow front chamber, which is more common in long-sighted people and tends to increase with age. It is also more common in women and in some ethnic groups. Attacks are often triggered in dim light, when the pupil widens and the folded iris crowds the already narrow drainage angle; this is why symptoms may start in the evening or in a darkened room. Some medicines that widen the pupil, and rarely certain other drugs, can set off an attack in a susceptible eye. Opticians sometimes spot narrow angles during a routine eye check and can arrange preventive treatment, so keeping up regular eye tests is worthwhile, particularly as you get older.

Treatment and prevention

In hospital, the emergency team works quickly to lower the pressure inside the eye using medicines, often given as drops and sometimes into a vein, to calm the eye and reduce the fluid. Once the pressure is controlled, a small opening is usually made in the iris with a laser to create a new escape route for the fluid and stop the angle closing again; the other eye is often treated too, because it is frequently at risk as well. After an attack, follow-up checks make sure the pressure stays controlled and the optic nerve is monitored. The key messages are simple: a sudden painful red eye with blurred vision, halos and vomiting is an emergency that needs same-day treatment, and keeping up regular eye tests helps narrow angles be found before an attack happens.