GDx Glaucoma Test

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Glaucoma is a disease that causes thinning of the nerve fibre layer in the retina and over time results in a gradual loss of vision which could lead to blindness if left untreated. Glaucoma is often called the "sneak thief of sight" because it is painless and symptoms appear slowly. In fact up to 50% of those with the disease remain unaware that they have it.

The best way to preserve your sight is early detection of the disease.

Introducing the revolutionary Zeiss GDx test

The Zeiss GDx Nerve Fibre Analyser test utilises a revolutionary technology that can help detect early glaucoma before any vision loss has occured. As a result, we will have more time to treat the disease and protect the vision.

When the GDx scans your eyes it is measuring the thickness of the nerve fibre layer in the back of the eye by using an invisible, safe, low powered laser. The measurements of the nerve fibre layer are mapped by the computer and compared to a database of normal values. An abnormally thin nerve fibre layer may indicate that glaucoma is present.

How does the Zeiss GDx examination work?

The Zeiss GDx examination is very quick and comfortable. The complete test takes about 5 minutes.

Once your details have been entered into the computer you are asked to simply rest your cheeks and forehead onto the head rest and look into the instrument while your eyes are scanned. The machine will examine one eye at a time and the examination takes approximately 5 seconds per eye. You will see stripes of red light with a flashing dot in the nasal quadrant and you will be asked to blink and then stare at the dot. An easy to interpret colour map of your retinal nerve fibre layer will be produced by the system which can then be quickly analysed in the consulting room by one of our optometrists.

Normal nerve fibres Moderate nerve fibres loss Severe nerve fibres loss

Normal Vision Moderate glaucoma Severe glaucoma

Is the Zeiss GDx test covered by the NHS eye examination or private eye examination?

A few eye hospitals in Britain have the GDx or similar machines but it is currently not covered by the NHS eye examination or by our private eye examination. If you would like to have a GDx test a charge of £28.00 applies.

We are committed to providing a comprehensive eyecare service to our patients and we believe the GDx examination has great advantages over the standard testing for glaucoma. We also hope that it will give peace of mind to anyone who chooses to have the test.

What is the advantage of the GDx examination over the standard testing for glaucoma?

GDx Test
The GDx examination can assist in detecting nerve fibre layer loss before any loss of vision has occurred and, therefore, the patient can be treated more quickly. The results are initially compared to a database of normal patients but upon further visits it also provides a comprehensive history that enables us to analyse the results and detect if there is any loss of nerve fibre thickness which may be an indication of glaucoma.

It is used for diagnosis of early glaucoma; for follow up of glaucoma patients under treatment and in relatives of glaucoma patients, to establish a baseline from which to work as these people have a five times greater risk of glaucoma.

Eye Pressure Test
An eye pressure test is normally used to detect glaucoma, however a number of those who develop glaucoma have normal eye pressures.

We have two methods of testing the eye pressure, the puff of air test normally used in an examination along with Goldman tonometry, the gold standard used in the hospitals, which involves the use of an anaesthetic.

Visual Field Tests
A visual field test shows the progression of the disease and is vital in monitoring glaucoma. Often 25-40% of the nerve fibre thinning has already taken place though before a visual field test can detect a problem.

Optic Nerve Assessment
Changes can be observed at the back of the eye to show glaucoma damage but these changes often occur after nerve fibre thinning has already taken place and visual field has been lost.

Who should be tested for Glaucoma?

Glaucoma can affect people of all ages and races however those at greatest risk are:-

• People over the age of 40
• Anyone with high eye pressure
• Anyone with a family history of glaucoma
• People of African or Caribbean origin
• Diabetics
• Anyone who is very short-sighted
• Long-term steroid users

Please call 020 8642 0563 if you would like to contact us to book a GDx examination.

Alternatively, if you wish to discuss this test with your optometrist at your next eye examination he will be happy to answer your questions.