Narrow angles and angle closure

The eye constantly makes a clear fluid that has to drain out. It leaves through the angle, the corner where the cornea meets the iris. In most people that corner is wide open. In some it is so narrow that the iris sits almost against the drain.

Depending on how far it has gone, there are three situations:

• Narrow angle (angle-closure suspect): the drain is narrow, but the pressure is normal and there is no damage.
• Angle closure: the iris is already touching or partly stuck to the drain, or the pressure has gone up.
• Angle-closure glaucoma: on top of that, the optic nerve is already damaged.

It is diagnosed with gonioscopy: a lens placed on the eye, with anaesthetic drops, that lets me see the angle directly. I do it in dim light, because the pupil then opens and it is easier to see whether the angle tends to close.

• Long-sighted people, because their eyes tend to be smaller, with less room at the front.
• People over 50 or 60. The natural lens grows with age and gradually pushes the iris forward.
• Women and people of Asian descent.
• Anyone with relatives who have angle closure or have had a glaucoma attack.
• Short eyes, or eyes with little room in front of the iris, which I can see on examination and on biometry.

If the angle shuts completely, the fluid cannot get out and the pressure rises sharply within hours. It tends to happen in dim light, when the pupil widens, or after taking a medicine that dilates it. The symptoms are hard to miss:

• Severe pain in the eye and head, on the same side.
• A very red eye.
• Blurred vision, as if looking through fog.
• Coloured halos around lights.
• Nausea and vomiting. It is sometimes mistaken for a stomach problem or a migraine.

Sometimes an attack is preceded by warning episodes: spells of blurred vision, halos around lights or a dull ache in the eye, especially in the evening, that settle on their own. If this has happened to you, tell me even if you feel fine now.

The other eye matters too: about half of people who have had an attack in one eye go on to have one in the other within the next 5 years if it is left untreated. That is why it gets a preventive iridotomy when its angle is also narrow.

If you have narrow angles and have not had laser yet, some medicines that widen the pupil can trigger an attack. They include:

• Decongestants, cold and flu remedies, allergy medicines and sleeping aids, including those sold without a prescription.
• Some antidepressants and other psychiatric medicines.
• Medicines for travel sickness or overactive bladder.
• Some inhalers for COPD or asthma, such as ipratropium or salbutamol.
• The drops used to dilate the pupil for an eye examination.

When a patient leaflet says "contraindicated in glaucoma", it almost always means this type of glaucoma. If you have untreated narrow angles, ask before taking it. Once you have had an iridotomy, most of those medicines can be taken without any problem.

Separately, topiramate (for epilepsy or migraine) and some sulfonamide drugs can close the angle through a different mechanism, even in eyes that did not have narrow angles and even after an iridotomy. If you notice blurred vision or eye pain soon after starting one of them, get checked straight away.

At the check-up I make sure the opening is patent and repeat gonioscopy to see how much the angle has widened. After that I keep an eye on the pressure and the optic nerve as often as your case needs.

If the pressure stays high despite the laser, or the nerve was already damaged, follow-up becomes the same as for open-angle glaucoma: drops and check-ups with OCT and visual field tests.