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This factsheet is for people who have glaucoma, or who would like information about it.

Glaucoma is the name for a group of eye conditions where your optic nerve is damaged and vision deteriorates.

About glaucoma

If you have glaucoma, your optic nerve (the nerve that connects your eye to your brain) is damaged at the point where it leaves your eye.

Sometimes this can be the result of an increase in pressure in your eye, which usually happens when fluid (the aqueous humour) in the front part of your eye (the anterior chamber) doesn't drain away properly. Usually the amount of fluid produced in your eye is balanced by the amount draining away, so the pressure in the front part of your eye remains controlled. If you have glaucoma, the pressure within your eye can be so high that your optic nerve is damaged and you may begin to lose your sight.

Glaucoma can also result from a weakness in your optic nerve, which can lead to damage even when the pressure in your eye appears to be normal. In most people, glaucoma is caused by both high pressure and a weakness in the optic nerve to varying extents.

Glaucoma can affect both of your eyes, but one eye may be affected more than the other. If you get treatment early, it can prevent further sight loss.

Illustration showing the different parts of the eye

Types of glaucoma

Chronic open angle glaucoma

Chronic open angle glaucoma (also called primary open angle glaucoma) is the most common type. It develops very slowly and damage to your nerve and eyesight happens gradually.

You can get chronic glaucoma if the drainage channels (through which fluid in your eye flows) become blocked as this can slowly raise the pressure within your eye.

Normal tension glaucoma
A form of chronic glaucoma called normal tension glaucoma can occur even if the pressure in your eye is within the normal range, which is usually less than 22 millimetre of mercury (mm Hg). It's thought that the optic nerve may have a poor blood supply or a weakness.

Acute angle-closure glaucoma

This type of glaucoma happens when the pressure in your eye rises very quickly. The drainage angle that lies between the cornea (the clear window at the front of your eye) and the iris (the part that gives your eye its colour) narrows suddenly. This prevents fluid in your eye from flowing out of your eye.

Acute glaucoma can be very painful and you must seek urgent medical attention. It can cause permanent blindness unless treated quickly.

Secondary glaucoma

If you have other eye conditions, such as an injury to your eye or repeated inflammation, you can get secondary glaucoma. If you have diabetes, you may be at risk of developing a type of secondary glaucoma called rubeotic glaucoma.

Congenital glaucoma

This is a very rare condition where a baby is born with glaucoma. The tissues at the angle of the anterior chamber don’t develop properly and this slows the flow of the fluid out of the eye.

Symptoms of glaucoma

If you have chronic open angle or secondary glaucoma, you probably won't notice any symptoms until your sight has deteriorated considerably. This is because the first part of your sight to be affected is the outer or peripheral field of vision. Your central vision, which you use to focus on objects, isn't usually affected until much later.

Acute glaucoma tends to come on very quickly and symptoms include:

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

If you think you're having an attack of acute glaucoma, you must seek urgent medical attention.

It can be difficult to recognise symptoms of congenital glaucoma but if your baby has watering eyes, is very sensitive to light or has cloudy, white, enlarged eyes, make an appointment to see your GP.

Causes of glaucoma

Glaucoma is caused by an increase in pressure within your eye or a weakness in the optic nerve, or both.

You're more likely to get glaucoma later in life. For example, chronic open angle glaucoma is uncommon in people under 40, but it affects one in a 100 people aged over 40 and around five in a 100 people over 65.

Other factors that can increase your chances of getting glaucoma include:

  • ethnicity – if you're of African or black Caribbean origin, you're more at risk of getting chronic open angle glaucoma and it may affect you earlier in life and be more severe, while if you’re of Asian descent, you’re more likely to get acute angle-closure glaucoma
  • a family history of glaucoma
  • being very short-sighted
  • diabetes

Diagnosis of glaucoma

You may not have any symptoms until you start to lose your sight. Therefore, screening tests are important to detect glaucoma. 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.

As glaucoma is more common if you're over 40, it's important to have an eye test at least every two years from this age onwards. It's also important to be tested regularly if you're at risk of developing glaucoma, for example if a family member has it or you have diabetes.

An eye test usually takes about 30 minutes and includes a number of tests for glaucoma. Your optometrist may:

  • look at your optic nerve by shining a light from a torch instrument into your eye
  • look at the thickness of your cornea
  • measure the pressure in your eye using a tonometry test – a small amount of pressure is applied to your eye using a tiny tool or a warm puff of air
  • measure your field of vision in a perimetry test by showing you a sequence of spots of light on a screen and asking you which ones you can see

If your optometrist thinks you may have glaucoma, he or she will refer you to an ophthalmologist (a doctor who specialises in eye health, including eye surgery) for more tests. These may include a test to examine the area in your eye where the fluid drains out.

Treatment of glaucoma

Treatment for glaucoma aims to lower the pressure inside your eye to reduce your risk of losing your sight or prevent any further loss of sight. Treatment can't reverse any existing optic nerve damage, so it won't improve your sight if it has already deteriorated.


Eye drops to treat glaucoma include:

  • prostaglandin analogues that help your eye's internal fluid drain out more quickly
  • beta-blockers that reduce the pressure in your eye – they slow down the build-up of fluid by reducing the production of it
  • carbonic anhydrase inhibitors that lower pressure in your eye by reducing fluid build-up
  • sympathomimetics that reduce pressure in your eye and help the fluid build-up to drain away

Several other types of medicine are available as alternatives or in addition to prostaglandins or beta-blockers. It's important that you follow your ophthalmologist’s advice and use the medicines as he or she advises to ensure the treatment is effective. If you don't, the pressure in your eye will rise again.

If you think your medicine is causing a side-effect, speak to your ophthalmologist as soon as possible. He or she can advise you and if necessary, prescribe alternative eye drops or consider other treatments.

Always ask your doctor for advice and read the patient information leaflet that comes with your medicine.


There are a range of operations to treat glaucoma. The operation you have will depend on the type of glaucoma you have and how severe it is – ask your ophthalmologist which is best for you.

Laser treatment
Laser treatment uses a laser to open the holes in the draining system in your eye to help fluid drain out or to stop your eye producing as much fluid. Laser treatment may also be used to make a small hole in your iris if you are at increased risk of or have acute angle closure glaucoma. This allows fluid in your eye to circulate and may open the angle to reduce the risk of it closing

Laser treatments are usually quick and cause little discomfort. It can be done under local anaesthesia and you will be able to go home the same day. The success of this type of treatment varies from person to person, and you may need to continue using eye drops after treatment.

Trabeculectomy surgery
You may need surgery if medicines and/or laser treatment haven't lowered the pressure in your eye.

There are a range of operations; the most commonly performed is trabeculectomy. In this operation a tiny opening is created in your eye wall to allow fluid to escape under the thin lining of the white of your eye (the conjunctiva) and be absorbed back into your bloodstream. You may have the operation under local or general anaesthesia – ask your surgeon for advice.

Prevention of glaucoma

If you're over 40, it's important to have an eye test every two years to check for the early signs of glaucoma. If one of your parents, children, brother or sister has glaucoma, have an eye test every year.


Produced by Kerry McKeagney, Bupa's Health Information Team, February 2012.

For answers to frequently asked questions on this topic, see FAQs.

For sources and links to further information, see Resources.

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  • This information was published by Bupa's Health Information Team and is based on reputable sources of medical evidence. It has been reviewed by appropriate medical or clinical professionals. Photos are only for illustrative purposes and do not reflect every presentation of a condition. The content is intended only for general information and does not replace the need for personal advice from a qualified health professional. For more details on how we produce our content and its sources, visit the about our health information page.

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