Investigating and treating AMD

Investigations for macular degeneration
- Vision assessment
- The Amsler grid
- OCT scanning
- Fluorescein angiography
How is dry AMD treated?
How is wet AMD treated?
Coping with AMD

 

Investigations for macular degeneration

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Vision assessment:

Each time you come to clinic your vision will be checked.

You will be given eye drops to dilate your pupil, which allows your retina to be examined. These drops take about twenty minutes to work and their effect may last several hours. Your vision will be blurred for a while and your eyes may be temporarily sensitive to light.

It is advisable not to drive to clinic appointments.

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The Amsler grid:

The Amsler grid is used to test your vision in an effort to detect any changes occurring at the macula.

Whilst some change will be apparent in dry disease, use of the Amsler grid is essential in wet disease where it is important to identify any deterioration at the earliest opportunity.

  • The grid should be held about twelve inches away from your face.

  • Whilst wearing the glasses you use for reading, cover one eye at a time with the palm of your hand.

  • With the uncovered eye, stare at the dot in the centre of the grid.

All four corners of the grid should be visible and the lines of the grid should appear straight and unbroken. If you see any holes or blurry spots, or the lines look wavy, fuzzy, crooked or broken, you should be seen within a few days.

Example of an Amsler grid
viewed with macular degeneration

An Amsler Grid:


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OCT scanning:

What is OCT scanning?

OCT stands for Optical Coherence Tomography. The picture obtained is essentially a cross-sectional slice, taken through the layers of the retina and the eye wall on which it sits.

OCT is quick, completely safe and totally painless. It does not involve any injections or x-rays. The quality of images produced on OCT has completely changed the way we diagnose and treat many retinal conditions.

What do I need to do before the test?

You should not drive to clinic. When you arrive you will have your vision assessed and dilating drops will be put into your eyes.

How long will I be at the clinic?

You can expect to be at the clinic for about one hour. The dilating drops take approximately twenty minutes to take effect. The OCT scan takes about ten to fifteen minutes to complete.

What does the test involve?

You will be asked to place your chin on a rest very similar to the slit lamp used in a standard examination. You look into a small box and will be asked to focus on a dot or line while the test is carried out. It is no more difficult than having a photograph taken.

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Fluorescein Angiography:

What is fluorescein angiography?

Fluorescein angiography is a photographic test using a specialised camera system and a photosensitive dye. It is not an x-ray and the dye used is an orange vegetable dye, not iodine-based like those used in x-rays and scans.

What do I need to do before the test?

There is no special preparation for the test. You may eat and drink as normal and it is important that you take your regular medication. It is advisable to bring someone with you. You should not drive to clinic. When you arrive your vision will be assessed and dilating drops will be put into your eyes.

How long will I be at the clinic?

You can expect to be at the clinic between one and two hours. The dilating drops take approximately twenty minutes to take effect. The fluorescein angiogram takes about fifteen to twenty minutes to complete. Andrew Luff will see the results when they are available.

What does the test involve?

The test begins with the photographer taking colour photographs of the retina with a digital camera. A small amount of fluorescein dye is then injected into a vein in your arm or the back of your hand. This is not painful. The dye travels quickly to the blood vessels of your eye. Over the next few minutes the photographer takes a series of photographs that record the passage of the dye through retinal blood vessels.

Does the test cause any reactions?

Most people suffer no ill effects from the test other than blurred vision for a few hours caused by the dilating drops and dazzle from the flash of the camera. A small number of people may experience nausea as the dye is injected. This quickly passes. A mild skin irritation may occur.
There is a one in a million risk of anaphylaxis (a major allergic reaction to the dye).

Will the test cause any side effects?

You may notice after the injection that the fluorescein dye has left your skin with a yellow tinge. This soon passes out of your body through your urine, which will appear orange the first few times you pass water following the test.

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How is dry AMD treated?

At present there is no specific treatment to reverse the damage or provide a cure for dry disease. Our aim is to concentrate on preventative measures, primarily tackling the risk factors for AMD.

Current smokers are strongly advised to stop.

All patients should have their blood pressure checked regularly and those considered “borderline” should be treated.

Good quality sunglasses should be worn in bright conditions, even in winter.

There is good evidence that dietary supplements may help to slow the disease progression. The Age-Related Eye Disease Study proved the benefit of high doses of vitamins A, C and E combined with zinc. It is normally recommended that Lutein, a naturally occurring vegetable pigment, is added to the supplement. Lutein gives the macula its healthy yellow colour, which helps protect against the potentially damaging effect of light. All patients are encouraged to eat a diet high in fresh fruit and brightly coloured vegetables.

Until recently, no surgery was appropriate to help with dry AMD. Now, for the first time, a surgical procedure may improve the quality of vision. This is the IOL-VIP, a telescopic implant lens system developed specifically to improve central vision in patients with macular disease. Further information can be found on the “IOL VIP” section of our website.

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How is wet AMD treated?

Treatment for wet AMD has been revolutionised by the development and application of anti-VEGF injection therapies. It was in 2005 that the first injections were performed in the United Kingdom and that wet AMD was, for the first time, recognised as a treatable condition with a realistic prospect of visual improvement.

Before the development of injections such as Lucentis and Avastin, laser treatments had been attempted, but with limited success. Thermal lasers could be used to burn the abnormal blood vessels beneath the retina, but damage to surrounding tissue was inevitable and treatment was only really successful in those few cases where the point of leakage was away from the centre of the macula.

A refinement in the form of “cold laser” was attempted with treatments such as photodynamic therapy (PDT) and transpupillary thermo-therapy (TTT).

Although effective in limiting the damage to healthy retina adjacent to the abnormal vessels, these techniques achieved only moderate success and have now been replaced almost completely by intravitreal injection.

Research has shown that the stimulus for growth of abnormal blood vessels is a protein produced by the ageing eye, which is known as vascular endothelial growth factor or, more conveniently, VEGF.

We still do not understand the many complexities of AMD and cannot always say why the eye produces VEGF, but we are able to block the damaging effect of this growth factor with drugs such as Lucentis and Avastin.

These drugs are antibodies which effectively “mop up” the damaging growth factor produced by the eye. Anti-VEGF agents appear to prevent both the development of neovascularisation and fluid leakage from the abnormal blood vessels.

Lucentis has been most extensively studied with results showing that visual loss can be halted in ninety per cent of cases and a substantial improvement in vision seen in about thirty per cent of cases. Unfortunately, multiple injections may be required and the long term duration of treatment is, as yet, unknown.

Research continues to identify better and more long lasting injection treatments. Eylea, which works in a slightly different way from Avastin and Lucentis (but still acts through reducing VEGF levels in the eye), requires less frequent injections. After an initial loading phase (3 injections over 3 months) many patients can then be controlled with an injection every two months, rather than monthly.

Further information on these treatments can be found in the “injection treatments” section of our website.

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Coping with AMD

Although there may be no cure for your macular degeneration, help and equipment are available to overcome some of the practical problems of daily living, such as reading and watching television.

If you have not already been registered as sight-impaired, this may be something you wish to consider. Registration will put you in touch with both social workers and local organisations experienced in the needs of the sight-impaired, who can help you develop practical ways to cope with your AMD.

There are a number of low vision aids available, such as magnifying devices, improved lighting and coloured filters for spectacles.

For further information visit the website www.visionenhancers.co.uk, or please ask our secretarial team for a catalogue.


Useful contacts for help and advice

Royal National Institute of Blind People (RNIB)
www.rnib.org.uk
RNIB Helpline: 0845 766 9999

Macular Disease Society
www.maculardisease.org
01264 350551

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