What is glaucoma?

Glaucoma refers to a number of eye conditions where the optic nerve is damaged. Glaucoma can be caused by changes to eye pressure, the eye needs pressure to keep the eyeball in shape. In other cases glaucoma can be caused by a weakness in the optic nerve.

Eye pressure rises if the fluid produced in the eye can not drain or if too much is produced. Damage can occur when pressure within the eye increases and presses on the optic nerve. A sudden high pressure can damage the optic nerve immediately. It is more common for there to be a lower level of pressure which causes damage more slowly and sight will gradually be lost.

41. Glaucoma

This change in pressure leads to a reduction in the field of vision and in the ability to see clearly. Glaucoma sufferers are often unaware until significant damage has occurred.

There are four main types of glaucoma

Acute glaucoma

Acute glaucoma happens quickly. This can occur when there is a sudden blockage to the flow of aqueous fluid in the eye. It can be painful and cause permanent damage to your sight if not treated properly.

Chronic glaucoma

Chronic glaucoma is the more common type of glaucoma and can develop over many years. Eye pressure rises very slowly and there is no pain but the field of vision gradually becomes impaired.

Developmental glaucoma

Developmental or congenital glaucoma is a rare condition which babies have and is caused by defects in the drainage system in the eye . The majority of cases are diagnosed by the age of one. If parents notice their child has either a cloudy, white, enlarged or protruding eye they should consult a doctor.

Secondary Glaucoma

Another eye condition can cause a rise in eye pressure. There may be symptoms of secondary glaucoma following an eye injury, an infection, inflammation, a tumour or an enlarged cataract.

What are the symptoms of chronic glaucoma?

Chronic glaucoma can be hard to detect as eyesight may seem normal and there is no associated pain. There may be an early loss of field of vision in the shape of an arc above or below the centre when looking straight. This can spread outwards and inwards. The centre of vision is last affected so this eventually becomes like looking through a long tube, this is referred to as tunnel vision. Eventually even this sight would be lost.

What are the causes of chronic glaucoma?

  • Age – glaucoma is more common in older people. It is rare to have glaucoma below the age of 40. Glaucoma affects 1% of people over the age of 40 and 5% of people older than 65.
  • Family history – people with close relatives who have chronic glaucoma are more likely to develop glaucoma. You should have a regular eye test and one every year once you are older than 40.
  • Race – chronic glaucoma is more common in people of African origin, it may develop earlier than average and be more severe.
  • Short sight – people with a high degree of myopia (short sightedness) are more likely to develop chronic glaucoma.
  • Diabetes – having diabetes increases the risk of developing glaucoma.

What should I do?

Glaucoma is more common over the age of 40 and it is advised that you have an eye test at least every two years and ask for three very simple glaucoma tests from your optician.

Your optician will:

  • Observe the optic nerve by shining the light from a special torch in your eye.
  • Measure the pressure in the eye using a special instrument.
  • Test the field of vision by asking you which lights you can see on a screen.

It is important to have your eyes tested regularly because chronic glaucoma can go undetected as it gradually develops and your sight will be at risk.

If you are over the age of 40 and have an immediate family member who has glaucoma you are entitled to a free sight test once a year with the NHS.

Can chronic glaucoma be treated?

Early diagnosis is essential as damage can be kept to a minimum but once it has been done it can not be repaired.

Eye drops are used to lower the pressure in the eye by reducing the fluid in the eye by opening up the drainage channels so excess liquid can drain away.

Some treatments also aim to improve blood supply of the optic nerve. Laser treatment or an operation called a trabeculectomy is can be used to improve the drainage of fluids from your eye.

As glaucoma is painless people can become inconsistent with their use of eye drops which can result in severe sight loss. Some people stop using them because they find eye drops uncomfortable. It is important if you have glaucoma to use your prescribed eye drops to prevent irreparable sight loss. If you are having problems using eye drops ask you eye doctor for help.

Is there a cure?

It is not possible to cure damage but it can be kept to a minimum with treatment. It is very important to have an eye test as early diagnosis and treatment can ensure that damage does not cause complete sight loss.

What are the symptoms of acute glaucoma?

Acute glaucoma can be a series of milder or one sudden attack. It is important that if you have any of these symptoms to seek medical help immediately.

Sudden attack

The sudden pressure can be very painful in the eye. Vision may deteriorate rapidly, it becomes red and might black out. The person suffering may have nausea and be vomiting and will need to go to the emergency department of a hospital immediately.

Mild attack

People can suffer from a series of mild attacks, which often happen in the evening. If there is discomfort in the eye and vision is misty with coloured rings around white lights you should contact a doctor immediately. These attacks may last for a few hours but the person might experience repeat symptoms. Each attack takes part of the field of vision.

What are the causes of acute glaucoma?

Acute glaucoma can happen very suddenly when the iris is pushed or pulled forward which blocks the angle of the eye where the fluid in the eye is drained.

What should I do?

Contact a doctor immediately if you think you are having any attacks. You will need to go to hospital so that the pain and pressure can be stopped.

Can acute glaucoma be treated?

Treatment needs to be administered immediately after an attack to relieve pain and pressure in the eye.

Acute glaucoma can be treated with medication which will reduce the production of aqueous liquid in the eye and improve its drainage.

If it is caught early acute glaucoma can usually be treated within a few hours and the eye will become more comfortable and vision will begin to return.

The follow up treatment to help prevent further attacks is usually laser treatment. You will have a small operation which will make a painless, small hole in the outer border of the iris to relieve the obstruction which will allow the liquid to drain away. It is common to have the same treatment on the other eye too as there is a high risk that it will develop in both eyes.

Is there a cure?

If acute glaucoma is diagnosed and treated immediately there may be a complete recovery of vision. Unfortunately if this is delayed there can be sight loss in the affected eye. If eye pressure remains high, the treatment is the same as chronic glaucoma.

How will I live with glaucoma?

Early diagnosis can prevent or slow down further damage by glaucoma. If you suffer from some sight loss there are resources available for you to help use your remaining vision as fully as possible.


It might be possible to remain driving if the loss of visual field is not too advanced. A special test can assess whether you meet the standards of the DVLA.

How will I cope?

Adjusting to having glaucoma may be difficult and overwhelming at first as it may involve some changes to your life. Devon in Sight is here to support you, to make life easier and to answer any questions you may have about your sight or day-to-day living.

There are some things which can be done to help

  • There are visual aids which can help you use your remaining vision.
  • Counselling is available if you need any emotional support or to talk about your diagnosis with someone.

Further information

This document was created in partnership with RNIB and Action for the Blind.

Devon in Sight is a local charity providing practical help and advice to people affected by sight loss, to maximise independence, wellbeing and choice.

You can call the RNIB Helpline on 0303 123 9999 and coordinators will provide you with impartial support and advice on everything to do with visual impairment.

RNIB have information on eye conditions from the Royal College of Ophthalmologists.

Moorfields Eye Hospital is one of the world’s largest centre for eye care and research.

International Glaucoma Association provide support and information to people with glaucoma.


Devon in Sight is not a medical organisation, therefore we can only provide general information that is not intended to be a substitute for a proper medical assessment. The information is also not intended to be used for individual cases. If you have a specific question about your eye condition, we recommend that you consult an eye care professional.

Devon in Sight has tried to ensure that the contents of these pages are accurate. However Devon in Sight will not accept liability for any loss or damage or inconvenience arising as a consequence of any use of or the inability to use any information on our website or in these fact sheets.

Visitors who use our website and use these factsheets and rely on any information do so at their own risk. Devon in Sight does not represent or warrant that the information accessible via the website or these fact sheets is accurate, complete or up to date.

The information contained on the website or these factsheets was correct at the time of writing. However, due to research and medical advances, the content may not be completely up to date.