Glaucoma is a group of eye diseases in which the optic nerve, which connects your eye to your brain, is damaged by the pressure of the fluid inside your eye.

This may be because the pressure is higher than normal, or because the nerve is more susceptible to damage from pressure. This may affect one or both of your eyes.

There are two main types of glaucoma: chronic glaucoma, which happens slowly and acute glaucoma which happens quickly. Chronic glaucoma is much more common than acute glaucoma.

If you have any concerns about the health of your eyes, please visit your local optometrist. Optometrists are the eye specialists on the high street. An eye examination is a vital health check and should be part of everyone’s normal health care.

Chronic Glaucoma

Anyone can develop chronic glaucoma. The risk of developing glaucoma goes up if you are:

  • Aged over 40
  • Very short-sighted
  • Of African or Caribbean origin
  • Closely related to someone with chronic glaucoma or
  • have raised pressure within your eye. This is called ocular hypertension (OHT)

If one of your parents or children, or a brother or sister, has glaucoma, and you are over 40, the NHS will pay for your eye examination. (In Scotland all eye examinations are provided under the NHS.)

How is chronic glaucoma detected?

Because the early stages of chronic glaucoma do not cause symptoms, the best way to catch it early is to have regular eye examinations.

There are three main tests to see if you have chronic glaucoma. The first one is where your optometrist looks at the nerve at the back of your eye using an ophthalmoscope, or a slit lamp to shine a light into your eye. They may also take a photograph or a scan of the nerve. This can be useful for future visits, to help them see if things have changed.

The second test is where the optometrist measures the pressure inside your eye. This may be done by using a machine which gently blows a puff of air at your eye, or by numbing your eye with drops and then gently pressing an instrument called a tonometer against it. The tests do not hurt, although the puff of air may make you jump a bit.

The third test is where the optometrist tests how wide your visual field is – how far you can see around you when you are looking straight ahead.

Sometimes you can have chronic glaucoma even if you have normal pressure, which is why you will usually have at least two of these three tests. If the results are not clear, you may be asked to do one or more of the tests again on a different day.

What will happen if I have chronic glaucoma?

If your optometrist suspects that you may have glaucoma, he or she will refer you to an ophthalmologist. If you have chronic glaucoma, you will be given eye drops to use every day. They will reduce the pressure and help control the build-up of fluid. They will not hurt.

Because you will not feel different in any way, you will not be able to tell that the treatment is working. This is why it is very important that you:

  • go to your follow-up appointments; and
  • keep on using the drops. If you find it hard to use the eye drops, you can get special bottles or holders to make it easier.

In a small number of cases, an ophthalmologist may recommend that you have an operation to help drain away the fluid.

Because chronic glaucoma causes no symptoms at first, if you are at risk you must have regular eye examinations to detect it early

There is no cure for chronic glaucoma but it can be treated effectively, normally with eye drops. Any existing eye damage will probably be permanent, but your sight could get much worse if you stop the treatment. It is very important that you use the eye drops every day, even if you cannot tell that they are helping.

Acute glaucoma

This is a type of glaucoma where the drainage channels inside your eye are blocked or damaged in some way. This causes the pressure inside your eye to increase rapidly. Sometimes the increased pressure can come and go, and some people get short bursts of pain and blurred vision. This can happen when your pupil gets bigger so it may be at night or when you are in a dark area (like the cinema) or when you are reading. Other symptoms are an ache in the eye which comes and goes, red eyes, or seeing coloured rings around white lights, or it can be a bit like looking through a haze or mist. If you get these symptoms it is important to act quickly, even if the symptoms appear to go away, as your vision may be damaged each time the symtpoms occur.

If you have these symptoms but they have gone away you should see your optometrist as soon as possible and mention that you have had these symptoms.  If you have these symptoms and they have not gone away you should go to the Accident and Emergency department immediately so that the pain and the pressure in the eye can be relieved.

People who are more likely to get acute glaucoma are:

  • People over 40
  • Women
  • People of East Asian or South Asian origin
  • People with a family history of closed-angle glaucoma
  • People who are long-sighted

Glaucoma tends to run in families

Because the early stages of glaucoma do not cause symptoms, the best way to catch it early is to have regular eye examinations.


This information is provided by the College of Optometrists. The College – a registered charity – is the professional body for optometry in the UK, working for the public benefit. It is a membership organisation and the most qualified practising optometrists in the UK are members. Membership of the College shows a commitment to the very highest clinical, ethical and professional standards.  Look for the letters MCOptom or FCOptom to see if your optometrist is a member.