Expert reviewer, Simon Taylor, Professor of Ophthalmology and Consultant Ophthalmic Surgeon
Next review due September 2022

Glaucoma is the name for a group of eye conditions where your vision gets worse because your optic nerve is damaged. Your optic nerve connects your eye to your brain. Usually this happens gradually as a result of an increase in pressure in your eye.

An older man is sitting at the beach with his dog

What is glaucoma?

The inside of the front of your eye (the anterior chamber) is filled with a fluid called the aqueous humour. This creates pressure in your eye, which is necessary to keep your eye healthy. The aqueous fluid is made in a ring of tissue behind the coloured part of your eye (the iris). It flows through your pupil and drains away through a spongy network of holes called the trabecular meshwork. This network sits in the angle where your iris and cornea (the clear front surface of your eye) meet.

Usually, aqueous fluid drains away at the same rate as you produce it, which keeps your eye at the right pressure. But if the fluid can’t leave your eye as quickly as you produce it, pressure builds up. This pressure can damage your optic nerve at the point where it leaves the back of your eye; this is called glaucoma. Your optic nerve is important to help you see because it takes signals from the light-sensitive cells at the back of your eye to your brain.

Glaucoma is the second most common cause of blindness in the world. If you’ve lost some of your vision, you can’t get it back but if you have treatment early, it can prevent further sight loss.

Types of glaucoma

There are a number of different types of glaucoma. The main types are as follows.

  • Open angle glaucoma. This happens when your aqueous fluid can’t drain away properly, often for no obvious reason. It is the most common type of glaucoma. It usually develops very slowly and damage to your eyesight happens gradually.
  • Angle closure glaucoma. This happens when the outer edge of your iris and cornea come into contact with each other. This stops your aqueous fluid from draining away. This type of glaucoma can be acute or chronic. If it is acute, the pressure in your eye rises very quickly. If it is chronic, the pressure develops more slowly.
  • Secondary glaucoma. This may happen if you have another eye condition such as an injury to your eye. You can also get it from taking certain medicines. Secondary glaucoma is much less common.
  • Congenital (developmental) glaucoma. This is a very rare condition where a baby is born with glaucoma. This happens when their eye’s drainage system doesn’t develop properly before they’re born.

Causes of glaucoma

Glaucoma is usually caused by an increase in pressure within your eye when the fluid in your eye can’t drain away properly. Sometimes, glaucoma may be caused by other things, for example a weakness in your optic nerve. This can lead to damage even when the pressure in your eye appears to be normal.

Risk of open angle glaucoma

You can get open angle glaucoma if the fluid in your eye can’t pass through the drainage channels properly. There’s usually no obvious reason for the blockage but this can slowly raise the pressure within your eye and damage your optic nerve.

You’re more likely to get glaucoma as you get older, particularly if you’re over 50. Other things that can increase your chances of getting open angle glaucoma include:

  • your ethnicity – you’re three times more at risk of developing glaucoma if you’re black (compared to if you’re white)
  • a family history of glaucoma – your risk is about double if you have a parent with glaucoma, and almost four times higher if a sibling has glaucoma
  • being short-sighted (you see objects closer to you more clearly)
  • if you have diabetes (type 1 and especially type 2)
  • if you use steroids for a long time such – as steroid eye drops, an injection into your eye tissue or steroid tablets
  • if you have high blood pressure – especially in older people – and cardiovascular disease

Risk of angle closure glaucoma

Angle closure glaucoma is related to the shape of your eye, which could be hereditary. You’re more likely to develop the condition if you’re far-sighted (you see objects far away more clearly) or of Asian ethnicity. Angle closure glaucoma is most common in people between 55 and 65, and women are more likely to develop it than men.

Symptoms of glaucoma

Open angle glaucoma

Open angle glaucoma usually affects the vision in both your eyes, but one eye can be affected more than the other. The first part of your sight to be affected is your outer (peripheral) field of vision. Your central vision isn’t usually affected until much later. If your field of vision has narrowed, the first sign of glaucoma you might notice is that you bump into things more often or trip down kerbs and steps. The sight loss from glaucoma usually happens gradually and isn’t painful.

Angle closure glaucoma

If you have chronic angle closure glaucoma that comes on slowly, you won’t usually get any symptoms until your sight is seriously affected.

If you have acute angle closure glaucoma that comes on quickly, you may get symptoms, which include:

  • sight loss
  • blurred vision or a halo around lights
  • pain in your eye
  • a headache
  • feeling sick or vomiting
  • redness in the white of your eye

If you notice these symptoms, seek urgent medical attention straight away – speak to an optician or go to Accident and Emergency. It can cause permanent blindness unless you get treatment quickly.

Congenital glaucoma

The signs of congenital (or developmental) glaucoma include watering eyes, sensitivity to light, cloudy eyes and twitching eyelids. These symptoms may be caused by something else, but if your child has any of them, ask your GP for advice.

Diagnosis of glaucoma

You may not have any symptoms of glaucoma until you start to lose your sight, so screening tests are important to detect it. An optometrist – a registered health professional who examines eyes, tests sight and dispenses glasses and contact lenses – can do these during a routine eye test.

Your optometrist may do the following.

  • Look at your optic nerve by shining a torch into your eye.
  • Measure the pressure in your eye using a tonometry test. They may apply a small amount of pressure to your eye using a warm puff of air. Or they can physically check the pressure using a small tool – you’ll be given anaesthetic eye drops first so you won’t feel anything.
  • Measure your field of vision in a perimetry test – you may be asked to look out for a light that flashes in your side vision.

Individually, these tests may be inconclusive, but together, the results give a clear indication if you’re developing glaucoma. If your optometrist thinks you may have glaucoma, they’ll refer you to an ophthalmologist for more tests. An ophthalmologist is a doctor who specialises in eye health, including eye surgery.

Your ophthalmologist may check the thickness of your cornea (the clear surface of your eye) because this can affect the pressure reading in your eye. A thick cornea can falsely increase the pressure reading in your eye while a thin cornea can cause an underestimate of the pressure. So, after your ophthalmologist has measured your cornea, they’ll have a better idea about how to interpret the tonometry test. There’s also some research that suggests a thinner cornea may increase your chances of getting glaucoma.

Your ophthalmologist will probably look at the structure of the area where fluid drains out of your eye to see if there’s any obstruction. They may want to do different scans of your eye, including an ultrasound or a scan called optical coherence tomography.

Babies and young children may be able to have tests and examinations under general anaesthesia, which means they’ll be asleep during the tests.

Treatment of glaucoma

Glaucoma treatment aims to lower the pressure inside your eye and reduce the risk of further damage to your sight. Treatment can’t reverse any existing damage, so it won’t improve your sight if this has already become poor.

Your optometrist and ophthalmologist will monitor you regularly to check if your treatment is working. This may be every three to 12 months, depending on how far your glaucoma had progressed when you were diagnosed. Once you’ve developed glaucoma, you’ll usually need treatment for the rest of your life.


Treatment for glaucoma may involve using eye drops at least once a day. The eye drops usually contain medicines including:

  • prostaglandin analogues and prostamides
  • beta-blockers
  • carbonic anhydrase inhibitors
  • alpha-2 adrenergic agonists
  • sympathomimetics
  • miotics

These medicines lower the pressure in your eye by allowing fluid to drain better or by reducing the amount of fluid your eyes produce. Your doctor will suggest the most suitable one for you and your type of glaucoma. You may need to take one medicine or a combination. It’s important to follow your ophthalmologist’s advice and always read the patient information leaflet that comes with your medicine.

If your eyes get itchy, red or swollen, you could be allergic to the medicine or preservatives commonly used in eye drops. Let your ophthalmologist know if you have any side-effects. For instance, if you notice changes in your vision or have any pain. Your doctor may be able to offer you another type of treatment, including preservative-free eye drops. But don’t stop using your eye drops without talking to your doctor first.

Laser treatment

Your ophthalmologist may suggest laser treatment to treat glaucoma. This helps the draining system in your eye work better. For open angle glaucoma, selective laser trabeculoplasty can improve how well the trabecular meshwork (the spongy network of holes) works to help fluid drain away.

You can have laser treatment under local anaesthesia. This completely blocks pain from the eye area. You’ll stay awake during the procedure and can usually go home the same day. Most people recover quickly. You’ll usually need to continue using eye drops after your treatment, to keep the pressure in your eye stable.


A trabeculectomy is one of the most common surgeries to treat glaucoma. In this operation, your surgeon will create a tiny opening in the white part of your eye (the sclera) to allow fluid to drain away. This lowers eye pressure in the long term for most people and they don’t need to continue taking eyedrops. However, some people may need further treatment. Serious complications include things like infection or bleeding in the eye, but these are rare. The surgery can be done under local or general anaesthesia, and you can usually leave hospital the same or the next day.

Another type of surgery you may be offered is the insertion of a drainage shunt. In this case, your surgeon will put a very small stent (hollow tube) through the sclera into the anterior chamber (front part) of your eye. This helps to drain fluid and reduce pressure.

There are other types of surgery to treat glaucoma – ask your doctor which is the best option for you.

Urgent treatment

Acute angle closure glaucoma that develops quickly is a medical emergency and you need to have treatment straight away. You’ll probably be given eye drops and you may need to lie in a way that relieves the pressure in your eye. You may need laser treatment or surgery on your iris.

Prevention of glaucoma

Glaucoma can’t be prevented but treatment can slow its progression. So, it’s important to detect it early.

If you’re over 40, you should have an eye test every two years. If you have a close relative that has glaucoma, you should be checked every:

  • three to five years if you’re between 20 and 29
  • two to four years if you’re between 30 and 64
  • one to two years from 65 onwards

If you’re known to be at risk, these regular checks should be free.

Living with glaucoma

Being diagnosed with glaucoma shouldn’t stop you doing everyday activities like watching television, using computers or reading. These won’t affect the pressure in your eyes or do any further damage.

You can also carry on with most sports and hobbies. Regular physical activity is good for your overall health and usually reduces rather than raises eye pressure. But check with your doctor if you plan to go scuba diving. You should also speak to your doctor if you play a wind instrument because this activity can temporarily raise your eye pressure.

It’s generally safe to fly with glaucoma as your eyes will adjust to changes in cabin pressure. But ask your doctor’s advice.

If glaucoma has affected your eyesight, making changes such as using brighter lighting in your home can make life easier. Ask your ophthalmologist or social services for advice on support available if your sight is impaired.

Frequently asked questions

  • As long as your central and peripheral vision meet the national recommended guidelines for driving, you should still be able to drive.

    If you have glaucoma in both eyes that affects your sight, you need to report it to the Driver and Vehicle Licensing Authority (DVLA). If glaucoma affects only one of your eyes and you have full vision in your other eye, you don’t need to tell the DVLA. But if you drive a bus, lorry or coach, you need to let the DVLA know if either one or both eyes are affected. You face a fine if glaucoma affects your driving and could be prosecuted if you’re involved in an accident as a result. If you’re unsure if you can drive, talk to your ophthalmologist who can give you advice about your personal circumstances.

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Related information

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    • Open-angle glaucoma. BMJ Best Practice., last reviewed June 2019
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    • Glaucoma (primary open angle) (POAG). The College of Optometrists., published 9 May 2018
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  • Reviewed by Rachael Mayfield-Blake, Freelance Health Editor, September 2019
    Expert reviewer, Simon Taylor, Professor of Ophthalmology and Consultant Ophthalmic Surgeon
    Next review due September 2022