AGE RELATED MACULAR DEGENERATION (MD, AMD or ARMD)
What is Age Related Macular Degeneration?
The exact cause of Age Related Macular Degeneration (MD, AMD or ARMD) is not fully understood, though recent years have seen a very dramatic advance in understanding of many of the genetic and cellular events that lead to the disease. It is by definition a disease that occurs in older people and does not occur under the age of 50. There are some rare conditions that appear similar to ARMD that affect younger patients (such as myopic degeneration) and they too have benefited from the advances in treatment.
ARMD is the leading cause of blindness in Australia. Approximately 1 Australian in 7 over the age of 50 will have some signs of ARMD. This increases dramatically with age. 14% of Australians over the age of 80 years old will suffer significant visual loss from the condition.
Fine vision, which we need to read, watch television, drive and recognise faces, comes from a small part of the back of the eye (the Retina) called the Macula. It is a very sensitive patch of special nerves that translate the light that is focused onto the back of the eye into vision, and it constitutes less than 5% of all the light sensitive retina. Any disturbance of the function of this small and special part of the eye affects vision. This central part of the eye works hard throughout your life. There is continuous re-cycling of important visual proteins in what is known as the “visual cycle”. For some reason in ARMD this process of recycling becomes imperfect with age. Normally the first signs of the condition is a build up of deposits in discreet clumps at the back of the eye. Ophthalmic surgeons call these “Drusen”. In themselves they often cause no problems. However they can indicate that problems may lie ahead and regular review by an Ophthalmologist is recommended. At Moreton Eye Group we have sophisticated equipment that allows us to help design a review programme, if appropriate, for you.
Eventually the disease causes the loss of the important cells that translate light into an electrical signal, which the brain turns into vision. Once this happens will you start to lose vision permanently. When these cells, called photoreceptors, are lost they will never recover. The new treatments for some types of ARMD need to be started early if vision is to be preserved.
Who gets Age Related Macular Degeneration?
As you get older the risk of developing Age Related Macular Degeneration (ARMD) increases. Within the general population certain groups seem to be at higher risk. Smoking has been proven to significantly increase the risk of ARMD. It is also thought that people of Northern European origin, of Celtic origin, may be at greater risk compared to other ethnic groups. Sunlight may have a part to play - but the evidence is not clear.
How do I know if I have ARMD?
In the early stages you probably will not experience any problems with your vision. However an ophthalmologist (or optometrist with the necessary skills and equipment to fully examine the back of your eye) will be able to tell you if you have any signs of the condition. If you do The Moreton Eye Group will be able to advise you if you will benefit from treatment or just a regular check up.
One early sign that can indicate a significant problem is the distortion of central vision. You may notice that straight lines, such as on a window frame, develop a “kink” or “wobble”. If you suffer this you must seek an expert eye examination immediately. An Amsler chart is a grid of squares that can be used as a test in early ARMD.
The Amsler Grid on the left is how they are normally viewed. On the right is how they can appear in early ARMD
Are there different types of Age Related Macular Degeneration?
Yes, there are broadly 2 types, known as “dry” and “wet”.
What is dry Age Related Macular Degeneration?
Over 90% of ARMD is termed “dry”. Dry macular degeneration is a slowly progressive disease which results in the loss of photoreceptors (the special cells that detect light). The early stages are characterised by “drusen”, which are white or creamy spots on the back of the retina that can be seen by an eye surgeon when they examine your eyes. Each year there is an approximate 10% chance that the dry ARMD can convert to the much more aggressive “wet” type (see below).
What is wet Age Related Macular Degeneration?
Wet AMD is so called because of the presence of new blood vessels and haemorrhage in the macula. It is much less common than “dry” ARMD but accounts for about 90% of blindness from ARMD. Until recently the development of wet ARMD led to permanent and swift loss of vision in nearly all cases. The development of new treatments has transformed the prognosis and now most patients can expect to preserve their vision so long as treatment is started promptly.
How is Age Related Macular Degeneration diagnosed?
The early stages of ARMD need an experienced ophthalmologist or optometrist to examine the eye. It is best to have your eyes examined periodically even if you have no symptoms as early intervention can be important. At Moreton Eye Group we can thoroughly examine your eyes and if treatment is required we have all the necessary expertise and equipment to treat you and so greatly increase your chance of preserving your vision.
Is it important to have my eyes checked?
Yes, the early stages of ARMD are often asymptomatic and so only an examination of the back of the eye will show if there are any problems.
How is Age Related Macular Degeneration treated?
The recent development of new treatments for wet ARMD have transformed the outcomes for patients. A new class of drugs call Anti Vascular Endothelial Growth Factor (Anti VEG-F) agents have been approved for the treatment of wet ARMD. Large trials have shown these drugs to be much more effective than any other treatments (The ANCHOR trials, PRONTO trials and VIEW trials). The new agents will halt the loss of vision in most patients and in up to 1/3 of patients actually improve vision. These drugs need to be delivered right onto the retina by a small injection with a tiny needle. Fortunately this is painless. The treatment is normally started with 3 injections one month apart. From then the condition is treated either monthly or as needed. Again at Moreton Eye Group our practice is influenced by large international trials that have shown that regular review with treatment as needed has very similar outcomes to monthly treatment - with the very great advantage of avoiding unnecessary injections and unnecessary risks.
There is no treatment for dry ARMD, but the rate of progression is normally slow. That said new treatments appear to be not too far away - for example with trials of stem cells now underway in humans.
Are there risks of treatment?
Each injection (intravitreal injection) does carry a risk of causing a small haemorrhage (bleed) over the white of the eye. This is relatively common but of no importance and spontaneously settles. You can think of it as a very small bruise. Occasionally discomfort can accompany the injection. Rarely the pressure can be raised in the eye - but this is treated with drops. More seriously - but much much more rarely, an injection can allow an infection into the eye resulting in a condition called endophthalmitis or cause a retinal detachment. If there is an infection the eye becomes red and painful and your doctor will need to give you antibiotics, again as an injection into the eye. What is clear is that untreated ARMD is the most significant cause of blindness in Australia, and the serious risks are very small.
Is there anything I can do to reduce the chance that my vision will be damaged by Age Related Macular Degeneration?
Smoking has been proven to increase the risk of ARMD - so if you smoke this is yet another good reason to stop. If you do stop smoking the risk of developing ARMD drops off quite sharply and after 13 years you will have barely any more risk than a non-smoker of ARMD or most other significant smoking related diseases.
Dietary supplements have been shown in 2 large trials called AREDS and AREDS 2 to reduce the risk of ARMD in high risk patients.
A diet rich in oily fish is also likely (but not proven) to help reduce the risk of vision loss from ARMD - and is implicated in other health benefits. Lutein, zeaxanthin and recently meso-zeaxanthin are likely to be beneficial to macular health. These are found in leafy green vegetables and members of the squash family. It is a complicated area with some conflicting advice out there - as is common with dietary and environmental factors. Sunshine has also been implicated, but again not proven, to be a risk factor for ARMD. Given the current understanding of the molecular basis of ARMD it is probably sensible to use quality sunglasses that reduce the Ultraviolet load - most ophthalmologists do!
You can discuss these issues fully with Dr Hay-Smith, who has had specific training in the management of ARMD, or one of the other experienced doctors at Moreton Eye Group.