Which medicines can affect glaucoma?

Many patient leaflets say that a medicine is contraindicated in glaucoma. The warning is alarming, but for most people with glaucoma it does not apply. It all depends on the type of glaucoma and on the treatment already received.

Why does the type of glaucoma matter?

In open-angle glaucoma, the most common type, the area through which fluid leaves the eye is open, and dilating the pupil does not close it. In closed or narrow angles, the iris lies very close to this drainage area. Some medicines dilate the pupil or push the iris forward and can suddenly close the drainage.

WHY THE TYPE OF GLAUCOMA MATTERS

Open angle and narrow angle

Fluid produced inside the eye drains through the angle, between the iris and the cornea.

1

Open angle

Fluid drains freely. Even with the pupil dilated, the drainage stays open. This is the case for most people with glaucoma.

2

Narrow angle

When the pupil dilates, the iris can fold and press against the drainage area. Fluid stops draining and the pressure rises within hours.

When this happens, an acute glaucoma attack occurs: severe eye pain, a red eye, blurred vision, coloured halos around lights, headache and sometimes nausea or vomiting. It is an emergency and you should go immediately to an emergency department with ophthalmology.

Which medicines can trigger an angle-closure attack?

• Decongestants and cold remedies with a vasoconstrictor effect, such as some tablets and drops for a blocked nose.
• Older, sedating antihistamines, used for allergy, itching or sleep.
• Anticholinergic medicines: some for overactive bladder, some for travel sickness, such as patches worn behind the ear, and some inhalers for asthma or COPD, especially when nebulised.
• Some antidepressants, particularly tricyclics. With newer antidepressants the risk is rare.
• Some medicines used for epilepsy and migraine, and some medicines of the sulfonamide family. They can cause an attack in both eyes at the same time, even in people who did not know they had narrow angles, usually within the first two weeks. Sudden blurred vision after starting one of these medicines needs urgent assessment.
• The drops used to dilate the pupil during eye examinations. That is why the angle is assessed before dilation.

What if I have had an iridotomy or cataract surgery?

After a laser iridotomy or cataract surgery, the risk of an attack is, in most cases, much lower. Even so, only your ophthalmologist can confirm whether the angle is open and whether you can take these medicines safely. Keep this information and show it to your family doctor and at the pharmacy.

Corticosteroids: the group that matters most in open-angle glaucoma

Corticosteroids, often called cortisone or steroids, can raise eye pressure. This happens in about one in three to four people, and more often in people with glaucoma or a family history of glaucoma. The risk is greatest with corticosteroids applied in or around the eye: drops, ointments on the eyelids and injections. It can also occur with tablets, injections, inhalers, nasal sprays or creams used for a long time.

This rise causes no symptoms. It usually appears weeks after starting and, in most people, disappears a few weeks after stopping. If you need corticosteroids for more than a few weeks, tell your ophthalmologist so that your eye pressure can be checked. Never stop a corticosteroid suddenly without talking to the person who prescribed it.

Your eye drops are medicines too

Glaucoma eye drops pass into the bloodstream in small amounts. Beta-blocker drops can lower the heart rate and worsen asthma or COPD, especially if you also take tablets from the same group for your heart or blood pressure. Always include your eye drops in the list of medicines you show to any doctor, dentist or pharmacist.

Are there medicines that protect against glaucoma?

Some studies have observed less glaucoma in people taking certain medicines, such as statins for cholesterol or some medicines for diabetes. These results are not yet confirmed and do not justify starting any medicine to prevent glaucoma.

What to do in practice

1. Know which type of glaucoma you have, open or closed angle, and whether you have had an iridotomy or surgery.
2. Keep an up-to-date list of all your medicines, including eye drops, and show it whenever something new is prescribed.
3. At the pharmacy, before buying cold remedies, decongestants or sleeping aids, say that you have glaucoma and which type.
4. If you have eye pain, a red eye and blurred vision, especially with nausea, go to an emergency department immediately.

For most people with open-angle glaucoma, everyday medicines can be taken normally. The most important exceptions are corticosteroids and, in untreated angle closure, medicines that dilate the pupil.

This information does not replace an individual medical assessment. Follow the advice of the team looking after you.