Age-related macular degeneration (also known as AMD) is the most common cause of blindness in people over the age of 50 in Australia as well as in most modern societies.
In order to understand precisely what AMD is, a basic understanding of the structure of the macula is useful. Please visit my informative page here to find out more.
The earliest changes in AMD occur at the level of Bruch’s membrane, followed by the retinal pigment epithelium (RPE) and the photoreceptors. Bruch’s membrane begins to thicken in patches or mounds called drusen. These can be small or large and differ in the type of fat (lipid) that forms them (these are not directly related to obesity). At this early stage, the condition may be called age-related maculopathy (ARM).
The larger drusen, particularly if they become confluent (grow and merge into each other), are at greater risk of progressing to more severe (or advanced) AMD. If symptoms are present at all, there may be some difficulty with vision in dim or low lighting, or possible distortion of central vision that makes straight lines look bent or wavy-letters and numbers look confusing or jumbled up when reading.
There are essentially two types of advanced or severe AMD – wet and dry – and they can both be present in any eye or person. Currently, it is not possible to predict whether AMD will develop or even which type, for that matter.
Below, you’ll find answers to a number of frequently asked questions regarding AMD, from ‘What causes dry macular degeneration?’ through to ‘Is macular degeneration curable?’.
Urgent wet age related macular degeneration treatment can prevent further visual loss and even improve vision significantly.
Dr Chauhan describes macular degeneration to a patient
What Is Wet Macular Degeneration?
Wet AMD is defined by the development of abnormal new blood vessels growing from the choroid through a break in Bruch’s membrane into the space under the RPE and sometimes into the space between the RPE and the photoreceptors. In themselves, these choroidal new vessels (CNV) do not affect vision, but they are fragile and immature. This means that they leak fluid and may bleed; hence this is known as ‘wet’ AMD.
It is the physical distortion of the macula and the consequent effect of the leaked fluid that causes the symptoms. Symptoms at this stage can range from mild distortion to loss of central vision, which can either occur suddenly or over a period of days to weeks. Urgent wet age related macular degeneration treatment can prevent further visual loss and even improve vision significantly.
What Is Dry Macular Degeneration?
Dry AMD is a degenerative change consisting of atrophy (withering away) or loss of the photoreceptors, the retinal pigment epithelium, and the underlying capillaries of the choroid (choriocapillaris). This is called geographic atrophy (GA) and tends to develop much more slowly, often over months or years. Symptoms of dry AMD are similar to those of wet AMD.
Unfortunately, there is no dry age related macular degeneration treatment available at the moment, but there are clinical trials that have reported encouraging interim results. In the past, many retinal specialists discharged patients with dry AMD, simply warning them of the symptoms of choroidal neovascularisation (wet AMD) and recommending urgent review at that stage.
I now keep a register of patients with dry AMD. My Box Hill clinic is one of only two sites in Victoria that are part of an international study of a new drug for dry AMD. However, the study results are not likely to be published before 2019 and I am not privy to any inside information as I am the ‘masked’ investigator in the study.
What Causes Macular Degeneration?
Wondering what causes dry macular degeneration? The five factors that are known, without doubt, to increase a person’s risk of developing both wet and dry age related macular degeneration are:
- A family history of AMD
Once you’re aware of what causes dry macular degeneration (and wet AMD), it’s recommended that you implement positive lifestyle changes in order to minimise your risk, such as maintaining a healthy diet and ceasing smoking.
What Are The Early Signs Of Macular Degeneration?
The main symptoms of AMD include increasing distortion, blurring, and central visual loss. If any of these are noticed, then urgent attention should be sought.
Many older people simply dismiss a decline in their ability to read or see as well as “just part of getting older.” Rather, these symptoms warrant urgent attention (within a few days).
How Can I Monitor Myself For Macular Degeneration?
Self-monitoring is an excellent way to avoid presenting to a retinal specialist too late, which is unfortunately all too common.
The Amsler chart is a very good way to detect a problem yourself and, after you have been seen by an ophthalmologist, to monitor yourself for any change. It is important to test each eye separately, with the other eye closed or covered, with reading glasses on if you need to wear them. Any distortion of the lines, or blurring or missing of parts of lines, can be significant. If you notice any changes, it is vital to act immediately by making an appointment with your retinal specialist.
Many people with severe AMD notice problems when reading, watching TV or simply looking at objects around them; for example, they see kinks in straight door frames or white lane markers on roads or suddenly can’t see the footy score in the corner of the TV. It’s easier for most people to choose straight objects and newsprint to test their vision for AMD, but they still need to wear the right glasses and cover one eye at a time.
I recommend that patients look regularly, once a week or so, at everyday objects and text in this way and call the clinic immediately if there is a change for the worse.
Do People Without Symptoms Need To Be Reviewed?
AMD develops over several years, so it is not uncommon to find early changes in the maculas of people in their fifties or sixties who have absolutely no symptoms whatsoever. As there is currently no preventative treatment established, some argue that there is no benefit to screening for AMD. However, screening may be worthwhile to identify those who may be eligible for treatment if/when it becomes available.
I was the first retinal specialist in the world to apply extremely short pulses of laser to the macula of patiients in an attempt to prevent progress of age related maculopathy (ARM) to age related macular degeneration (AMD). Subsequent studies are ongoing and results are expected in 2018.
Is Macular Degeneration Curable?
While there is no cure for wet or dry macular degeneration, a treatment does exist for wet AMD that can help to slow the progression of the disease.
Age-related Macular Degeneration Treatment
Until mid-2006, the two main treatments available for wet AMD disease were laser and photodynamic therapy (PDT). Both were aimed at preventing worsening of vision but didn’t often succeed, and only rarely resulted in improvement of vision.
Fortunately, it is now possible to prevent worsening of vision in nearly 95% of patients and improve vision significantly in up to 40% with repeated intravitreal injections of drugs. While this treatment is not a cure, it is able to suppress the problem for a short period of time. As a result, many patients now have treatment on a one- to three-monthly basis. At present, until alternatives become available, this is probably a lifelong ongoing treatment.
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