Diagnosing macular degeneration

In some cases, early age-related macular degeneration (AMD) may be detected during a routine eye test before it starts to cause symptoms.

If you're experiencing symptoms of macular degeneration , such as blurred central vision, visit your GP or make an appointment with an optometrist, a healthcare professional trained to recognize signs of eye problems.

Find your nearest optician .

Referral

If your GP or optometrist suspects macular degeneration, you'll be referred to an ophthalmologist, a doctor who specialises indiagnosing and treating eye conditions.

Your appointment will usually be at ahospital eye department. If you need to travel by car to the hospital, ask someone else to drive you back as the eye drops given to you may make your vision blurry.

Eye examination

The ophthalmologist will examine your eyes. You'll be given eye drops to enlarge your pupils. These take around half an hour to start working, and may make your vision blurry or your eyes sensitive to light. The effect of the eye drops will wear off after a few hours.

The ophthalmologist will use a magnifying device with a light attached to look at the back of your eyes, where your retina and macula are. They'll check for any abnormalities around your retina.

The ophthalmologist will then carry out a series of tests to confirm a diagnosis of macular degeneration.

Amsler grid

One of the first tests involves asking you to look at a special grid, known as an Amsler grid. The grid is made up of vertical and horizontal lines, with a dot in the middle.

If you have macular degeneration, it's likely some of the lines will appear faded, broken or distorted. Saying which lines are distorted or broken will give your ophthalmologist a better idea of the extent of the damage to your macula.

As the macula controls your central field of vision, it's usually the lines nearest to the centre of the grid that appear distorted.

Eyecare Trust has a version of the Amsler grid (PDF, 51.2kb) on its website that you can print off and use at home to check for possible signs of AMD.

Retinal imaging

As part of your diagnosis, your ophthalmologist will need to photograph your retinas to see what damage, if any, macular degeneration has caused.

As well as confirming the diagnosis, the images will prove useful in planning your treatment. There are several different ways of taking pictures of the retina.

Fundus photography

A fundus camera is a special camera used to take photographs of the inside of your eye. It can capture three-dimensional images of your macula. Your ophthalmologist can then look at the different layers of your retina to see what damage, if any, has occurred.

Fluorescein angiography

Arteriography is an examination that creates detailed images of your blood vessels and the bloodflow inside them. A special dye is injected into your blood vessels and pictures are taken that show any abnormalities inside them.

The procedure can confirm which type of AMD you have. It may be carried out if your ophthalmologist suspects wet AMD.

Your ophthalmologist will inject a special dye called fluorescein into a vein in your arm. The dyewill move through your blood vessels into your retina. They willlook into your eyesusing a magnifying device andtake a series of pictures using a special camera.

These images will allow your ophthalmologist to see whether any of the dye is leaking from the blood vessels behind your macula. If it is, this may confirmyou have wet AMD.

Indocyanine green (ICG) angiography

The technique used for indocyanine green (ICG) angiography is the same as for fluorescein angiography, but the dye is different. ICG dye can highlight slightly different problems in your eyes.

Optical coherence tomography (OCT)

Optical coherence tomography (OCT) uses special rays of light to scan your retina and produce an image of it. This can provide detailed information about your macula. For example, it will tell your ophthalmologist whether your macula is thickened or abnormal, and whether any fluid has leaked into the retina.

Staging of AMD

Once these tests have been completed, your ophthalmologist should be able to tell you how far your AMD has progressed.

Dry AMD has three main stages, described below.

• early at this stage there may be many small collections of drusen (deposits) inside the eye, a few medium-sized drusen, or some minor damage to your retina; early AMDmay not cause any noticeable symptoms
• intermediate there maybe some larger drusen inside the eye or some tissue damage to the outer section of the macula; you'll have a blurred spot in the centre of your vision
• advanced the centre of the macula is damaged;you'll have a large blurred central spot and find it difficult toread and recognise faces

Wet AMD is alwaysconsidered to bean advanced form of AMD.

Macula

The macula is a small spot at the centre of the retina. It is the part of your eye where incoming rays of light are focused.

Retina

The retina is the nerve tissue lining the back of the eye. It senses light and colour and sends it to the brain as electrical impulses.

X-ray

An X-ray is an imaging technique that uses high-energy radiation to show up abnormalities in bones and certain body tissue, such as breast tissue.