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Glaucoma

Published by Bupa's health information team, November 2007.

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 the pressure within your eye is raised to such a degree that the optic nerve becomes damaged and you begin to lose your vision. If it's treated early, the complications of glaucoma can be prevented.

• What is glaucoma?
• Symptoms
• Causes
• Diagnosis
• Treament
• Prevention
• Further information
• Sources

What is glaucoma?

Glaucoma is a condition in which the pressure inside the eye is raised. The increase in pressure usually happens when fluid (the aqueous humor) in the front part of the eye (the anterior chamber) doesn't drain away properly. Normally, the amount of fluid produced is balanced by the amount draining away, so the pressure in the front part of the eye stays constant.

The different parts of the eye

Types of glaucoma

Chronic glaucoma

This is also called primary open angle glaucoma and is the most common type. Over time, the drainage channels through which the aqueous humor flows slowly become blocked. The pressure within your eye rises very slowly so that any damage to the nerve and eyesight happens gradually. In chronic glaucoma the drainage angle of the iris is normal, unlike acute glaucoma (see Acute glaucoma).

Acute glaucoma

This is also called closed angle glaucoma. It occurs when the drainage angle of the iris narrows, preventing the aqueous humor from flowing into the drainage (outflow) channels. This can be painful and causes permanent sight damage unless treated quickly. The increase in pressure can be two or three times the normal eye pressure within an hour or so of the iris narrowing. This type of glaucoma is rare.

Secondary glaucoma

This occurs as a result of other eye conditions. It can develop after an eye injury or if you suffer from repeated inflammation in the eye.

Congenital glaucoma

This is a very rare condition, and means that a baby is born with glaucoma. The condition occurs when the baby's normal vision is still developing. Even if it's treated, congenital glaucoma sometimes causes blindness because it's difficult to diagnose.

Normal tension glaucoma

Normal tension glaucoma can occur when the pressure in the eye is within the normal range. It's thought that a poor blood supply or a weakness in the optic nerve may make the nerve more likely to become damaged by normal eye pressure.

Ocular hypertension

Ocular hypertension is a condition where the pressure increases moderately but there are no signs of loss of vision or optic nerve damage. This needs to be monitored as it can occasionally lead to optic nerve damage over time.

Symptoms

If you have chronic or secondary glaucoma, ocular hypertension or normal tension glaucoma, you probably won't notice any problems until your vision has deteriorated quite considerably. This is because the first part of the vision to be affected is the outer or peripheral field of vision. Central vision, used to focus on an object (eg when you are reading) is usually not affected until relatively late on in the disease.

Acute glaucoma

Acute glaucoma tends to come on very quickly. Symptoms include pain and blurred vision. Some people also feel sick, faint and vomit. In the early stages you may see misty rainbow coloured rings around white lights. If you think you are having an attack of acute glaucoma, you should go to hospital immediately.

Congenital glaucoma

It can be difficult to recognise symptoms of congenital glaucoma. If your baby or child has cloudy, white, hazy, enlarged or protruding eyes you should make an appointment to see your doctor immediately.

Causes

Age is the main risk factor for glaucoma. Not many people under the age of 40 will develop the condition, but two in 100 people over the age of 40 and five in 100 people over the age of 65 will develop chronic glaucoma.

If you are of African origin you are more at risk and it may affect you earlier in life and be more severe.

If you have a close relative with glaucoma, you are at greater risk and should have regular eye tests from the age of 35. People who are very short-sighted are also more prone to glaucoma.

If you have diabetes, your risk of developing chronic glaucoma is also higher.

Diagnosis

Screening tests are important to detect glaucoma before you get significant loss of vision. An optometrist (optician) can do these during a routine sight test. If you are concerned about glaucoma, see an optometrist for a consultation.

An eye test usually takes about 30 minutes. The optometrist may ask you about your general health and your medical history. You will be asked to read letters or look at pictures on a chart while a light is shone in your eyes. If you wear glasses you should take them with you and any medicines you are taking.

To test for glaucoma, you will be shown patterns of lights which you will be asked to describe. You will also have air blown into your eye and/or eye drops, to check the health of your eyes. These tests don't hurt.

Treament

Treatment for glaucoma aims to lower the internal pressure of the eye and prevent any loss of vision, or any further deterioration in vision. Options include medicine given as eye drops, laser treatment and surgery. Treatment can't reverse any existing optic nerve damage, so it won't improve your sight if it has already deteriorated.

Medicines

There are several different types of medicine available for treating glaucoma. They help lower the internal pressure of the eye by increasing the flow of fluid out through the trabecular meshwork, or by reducing production of fluid. Your doctor may prescribe a beta-blocker (such as timolol).

Several other types of medicines are available in drop and tablet form, as alternatives or in addition to beta-blockers. It's important that you use any prescribed eye drops everyday as advised by your doctor. If you don't, the pressure in the eye will rise again. There are combination eye drops available that may be more convenient if you need to use two different medicines.

There are different side-effects for each type of eye drop. All the eye drops can cause some irritation to the eyes. In addition, beta-blockers can cause itching and dry eyes. Side-effects of other types of medicine may include taste disturbance, darkening of the iris, thickening and lengthening of eye lashes, headaches and blurred vision. Ask your doctor for more information about these medicines.

Laser treatment

A laser can be used to open the holes in the trabecular meshwork. The procedure is usually quick and causes little discomfort. You won't need a general anaesthetic 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 laser treatment.

Surgery (trabeculectomy)

The effectiveness of newer medications for glaucoma has reduced the need for surgery. However, surgery is an option if medicines and/or laser treatment have failed to lower the pressure in your eye.

The operation is straightforward and involves creating a tiny opening in the eye wall, which allows fluid to escape into the loose tissue under the conjunctiva (the clear membrane that covers the white of the eye). From there the fluid is absorbed back into the bloodstream.

Prevention

All adults over the age of 40 should have regular eye tests to check for the early signs of glaucoma.

Further information

• IGA (International Glaucoma Association)
  01233 64 81 70
  www.iga.org.uk
• RNIB (Royal National Institute of Blind People)
  0845 766 9999
  www.rnib.org.uk

Sources

• British National Formulary (BNF) March 2007. London: BMJ Publishing Group, 2007. 53
• Glaucoma. BMJ Clinical Evidence.
  www.clinicalevidence.com
  accessed 18 June 2007
• Glaucoma. International Glaucoma Association (IGA).
  www.glaucoma-association.com
  accessed 18 June 2007
• Simon C, Everitt H, Kendrick T. Oxford Handbook of General Practice. 2nd ed. Oxford: 2005, 942-949
• Understanding glaucoma. Royal National Institute for the Blind (RNIB).
  www.rnib.org.uk
  accessed 28 February 2007
• Watts M. Living with Glaucoma. Great Britain: Sheldon Press, 2006

This information was published by BUPA's health information team and is based on reputable sources of medical evidence. It has been peer reviewed by Mr GS Bhermi, FRCophth, consultant ophthalmic surgeon, Southend Hospital; and BUPA doctors. The content is intended for general information only and does not replace the need for personal advice from a qualified health professional.

Publication date: November 2007. Expected review date: August 2009.

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