Peter Chau Referrers

 

Age Related Macular Degeneration Patient Information


AMD

 

What is the Macula?

The retina is a specialised layer of the inside of the back of the eye. It receives images of the real world. Light is focused by the cornea and lens on to the retina. It is analogous to the film in older cameras and to the layer of pixels in a digital camera. The retina registers images of the real world and transmits them to the brain where vision is appreciated.

The macula is a very specialised and sensitive part of the retina. It is responsible for fine vision including reading. It is responsible for straight ahead vision. Your brain will subconsciously align your eye so that the macula is pointed directly at the object of your interest. This could be a word or a letter while reading, or a road sign as you are driving.

Pixels in a camera are uniformly distributed at an equal distance from one another. In the eye however, the Rods and Cones (photoreceptors) are more densely packed at the macula

Atrophic AMD (Dry) Age Related Macular Degeneration

Dry Age Related Macular Degeneration is often likened to ageing itself and wearing out of the Macula. Typically, this is a slow process which occurs over many years. The medically appropriate name is Atrophic Age Related Macular Degeneration, or Atrophic AMD.

Once established there is no treatment that can improve vision in Atrophic AMD. There are however preventive strategies which delay the onset of Atrophic AMD.  These strategies are believed to slow down the progression of the disease.

Neovascular AMD (Wet/Exudative) Age Related Macular Degeneration

The growth of abnormal blood vessels under the Macula is the underlying problem in Neovascular AMD. The older terminology of “Exudative” AMD refers to the leakage of fluid and protein into the macula, interfering with the function of the photoreceptors and their connections to other nerve cells. The abnormal blood vessels can bleed into the Macula. Blood has a more destructive effect on photoreceptors than fluid. Up to a point, treatment can reverse this leakage and restore vision. Without treatment, scar tissue will destroy and replace the photoreceptors and interconnecting nerve cells. At this late stage, the damage is permanent, and treatment has little or no effect on poor vision.

Risk Factors for Neovascular AMD

These include:-

  • Age ( the greatest risk factor)
  • Family history
  • Smoking
  • Poor Diet

An Optometrist or Ophthalmologist can look at the Macula for:-

  • Drusen (yellow dots at the Macula)
  • Pigment irregularity
  • Atrophy

These are physical signs of Atrophic AMD. The presence of Atrophic AMD is a risk factor for Neovascular AMD. Not all patients with Atrophic AMD will necessarily develop Neovascular AMD. Some patients continue to have only Atrophic AMD for the rest of their life.

Self Monitoring With an Amsler Grid

If many risk factors apply or are detected by your Optometrist, follow up is needed.

Self-monitoring is an excellent way of detecting early macular changes. You may monitor yourself every week, or indeed every day using an Amsler Grid.

An Amsler Grid is a grid with evenly spaced horizontal and vertical straight lines that are parallel to each other. It is like graph paper with a dot in the middle.

How to use and Amsler Grid:

  • wear your reading glasses to do this test
  • test one eye at a time
  • look at the dot in the centre of the grid for the whole test

The lines should look straight and no lines should be missing.

If there are crooked lines of if something is missing, especially if this is of sudden onset, it is highly likely that there is fluid in the Macula.

Remember that the treatment for Neovascular AMD is most effective if given early, at the stage where only fluid is in the Macula and no permanent damage has yet occurred

Amsler Grid
http://www.drballitch.com/images/p-amsler-grid.gif

Assessment By Dr Peter Chau In Consulting Rooms

An assistant to Dr Peter Chau will measure your distance and near vision. Drops will be instilled into your eyes to dilate your pupils. This is necessary to examine the macula, perform tests and to photograph the Macula. The drops take at least half an hour to work.

The Macula will be assessed with Ocular Coherence Tomography (OCT). Two and three dimensional images show the shape of the Macula.. OCT is excellent at detecting fluid in or under the Macula.

A Fluorescein Angiogram will then be performed by Dr Chau. Written informed consent is required because a yellow dye is injected into the vein of an arm. This can rarely lead to an adverse reaction. The dye travels from the arm to the eye in about 20 seconds. Rapid flash photographs are taken as the dye transits through the eye circulation.

Fluorescein Angiogram is necessary to confirm the presence of the underlying abnormal blood vessels which cause Neovascular AMD and to obtain a Government subsidy for the cost of the Lucentis ($2000 per injection without subsidy).

Ocular Coherence Tomography Image Neovascular (Wet) AMD
Ocular Coherence Tomography Image Neovascular (Wet) AMD

Normal Macula

Normal Macular

Photography – Neovascular AMD
Neovascular AMD

 

 

 

 

 

First Treatment By Dr Peter Chau In Consulting Rooms

As soon as the diagnosis is confirmed with Fluorescein angiography, it is ideal to commence treatment immediately, as it is possible for the disease to suddenly worsen.

The diagnosis and management of Neovascular AMD will be rediscussed by Dr Chau and/or orthoptic staff.

The initial treatment is:

  • A series of 3 injections of Lucentis into the affected eye.
  • The injections are given 4 weeks apart
  • The first injection is usually given in the consulting rooms after the fluorescein angiography.
  • The second and third injections may be given in a Day Surgery Centre or consulting rooms

Treatment:
Treatment is given lying down with your head on a pillow.

The surface of the eye is numbed with drops (topical anaesthesia)

The eyelids and the surface of the eye is treated with Betadine antiseptic

The eyelids are dried with a sterile swab

The eyelids are held apart with a gentle sterile mechanical device

A sterile instrument is used to measure 3.0 to 4.0mm back from the colored part of the eye to the white of the eye

A tiny sterile needle is used to inject less than 1.0ml of LUCENTIS into the Vitreous Cavity in front of the Macula.

The first dose of an Antibiotic drop is given

You need to continue the Antibiotic drop 4 times daily for 4 days.
The eye is not covered

A scratchy feeling is common for up to 24hrs

Artificial tears/Lubricant drops can be useful to relieve these symptoms

The eye should not be painful

A painful eye with a marked drop in vision within the first few days suggests the possibility of a serious infection. This is rare but possible. Contact the consulting rooms as soon as possible.

The risk of serious infection with permanent visual loss (Endophthalmitis) after an eye injection is reported to be 1 in 2000. The risk is no different for injections given in consulting rooms versus injections given in a Day Surgery Centre. The risk of losing vision from untreated Neovascular AMD is very much higher.

Follow Up Treatment/Relapse and Retreatment

The aim of the first 3 injections of Lucentis is to “dry out” the Macula and improve vision.

The macula will remain “dry” for a period of time which cannot be determined ahead of time. Frequent monitoring is therefore needed for an indefinite period of time.

On each visit your vision will be measured and an OCT performed. It is exceedingly rare to require another Fluorescein Angiogram.

If your vision is stable and the Macula is “dry” then another follow up visit is scheduled.

Any detected new fluid or new blood is a sign of relapse and further injections (often but not always 3 again) are needed.

A relapse can often be detected before you notice a drop in vision.

We cannot monitor you every day, whereas you can monitor yourself using a Amsler Grid. Self-monitoring may enable you to detect a relapse before your next scheduled appointment. You can come in earlier to be treated with the greatest chance of maintaining good vision. You will come to realise that looking after Neovascular AMD is a long term strategy, where the follow up visits are as important as the injection.

Preventative Strategies

These include lifestyle modifications, diet and Oral Supplementation (tablets).
The Age Related Eye Diseases Study (AREDS) tested the effect of a formulation containing

  • Vitamins A, C & E
  • Beta Carotene (antioxidant)
  • Zinc and Copper (minerals)

We refer to this as the AREDS formulation. Over 3000 participants were enrolled in the study. No benefit was demonstrated in patients with early Atrophic AMD.   A benefit was however demonstrated for patients with moderate to severe AMD (when combined together). Untreated Neovascular AMD would fall under the Severe AMD category.

After 5 years of follow up, 28% of patients who took placebo (fake) tablets had marked vision loss.

After 5 years of follow up, 20% who took AREDS formulation had marked vision loss. The results were published in the year 2001, six years before Lucentis became available.

The AREDS formulation (tablets) reduced the risk of severe visual loss by 8% over a 5 year period.

During the study it was discovered that for patients who smoked, the risk of lung cancer was increased by Beta Carotene.

The best known product available over the counter is Macuvision manufactured by Blackmores.  Blackmores has removed the Beta Carotene. Macuvision is therefore no longer the same as the AREDS formulation. Only AREDS formulation was tested in the original Scientific clinical trial.

Smoking cigarettes is well known to increas your risk of vision loss in AMD. It is recommended to cease smoking when AMD is diagnosed  and take the original formulae used in the AREDS trials.

Summary

Prior to the availability of Intravitreal Injections of Lucentis in 2006 the outlook for vision in Neovascular AMD was very poor. Most patients lost their vision and became legally blind (vision worse than 6/60)

Lucentis does not cure Macular Degeneration

There is no doubt however that the combination of:

  • Early detection
  • Lucentis injections given promptly at the appropriate times
  • Continuous follow up and monitoring,

has enabled many patients to retain useful vision for as long as 5 years to date.

In the future we look forward to newer injectable agents that last twice as long in the vitreous cavity, which will halve the number of injections required.

Thereafter, we expect new therapies with different principles of treatment to further improve the outcomes of this potentially blinding disease.