Macular Degeneration
What is macular degeneration?
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This is a process where the critical light sensitive cells (photoreceptors), like pixels on your phone or on the TV, lose function and die. These cells are located where your vision is centered (in the macula) so whatever you directly look at becomes blurred. Straight lines may look wavy, details become blotchy and if you’re trying to read especially small print or see people's faces, that’s where you notice the difficulties, especially if the light is a bit dim. You may notice difficulties adapting from a very bright light, say from outside to a dimmer light, coming from outdoors to indoors.
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What happens if I get dry macular degeneration?
It may lead to loss of the ability to read, recognise faces, loss of driving independence and practical difficulties that require adaptation. Some patients require magnifiers and practical support.
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How quickly does dry macular degeneration progress?
It’s a gradual process that occurs over many years. Areas of tissue disintegrate leaving a bare area, like a patch of worn-out carpet. Initially there are small areas of damage spaced apart so by shifting your eye you can get around the problem. But these patches grow and join up so you may be able to see the letters on the chart when you have your vision tested but in real life it’s really quite difficult because you have a very small area of working tissue surrounded by blotches from damaged tissue. Then that tiny working area also dies. Not everyone deteriorates rapidly, but the average from the start of dry macular degeneration that’s not affecting the centre to more severe central loss can be as little as 2 years. In a UK study of 523 patients, 67% who had early dry macular degeneration but were able to drive lost this eligibility in 1.64 years (range 0.7 to 2.7 years). 16% of the patients became legally blind at 6.2 years (range 3.3 -8.5 years).
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How do I know if I’m going to deteriorate quickly?
There are various clues we look for to judge whether you’re likely to deteriorate faster. The size of the area that’s affected, how far it is from the centre, whether it’s a single area or multiple areas and what type of waste deposits, are there, new blood vessels in that area.
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What are the treatment options for dry macular degeneration?
There are two treatment options approved in the USA- both in the last year. Both are injections that are given either monthly or two monthly indefinitely. There are risks and the outcomes show small reductions of around 20% of the affected area getting larger but no improvement in vision or day-to-day function. They have not been approved by the UK authorities. The Valeda device is a non-invasive low light therapy that has shown very promising results. Unlike the injection treatments many patients have vision gains and slowing in their disease progression.
What happens in wet macular degeneration?
In wet macular degeneration, new blood vessels develop in areas of damage that leak fluid and sometimes bleed if untreated. This leads to scarring that becomes permanent and a sudden irreversible loss of central vision. Wet macular degeneration has been treated now for 15 years. The standard treatment is injections that are given in the eye on a regular long-term basis, typically every 8 weeks. We have newer injections now since last year. These show the potential for reducing the number of injections by increasing the gap between injections because these newer agents are lasting longer. That’s great because it means there’s the potential for fewer hospital visits and fewer injections. Different hospitals have different policies on which drugs they can use so not all patients will be on the injection that gives them the greatest gap between injections.
Why and when does macular degeneration begin?
Both wet and dry macular degeneration start with a common process. As we age, the support system for the light sensitive cells that we call the photoreceptors becomes stressed. Genes and environmental factors, especially smoking, can trigger or accelerate this process. The support cells (the RPE or retinal pigment epithelium) start to build up deposits of protein and fat that should have been eliminated in the bloodstream. These waste products (called drusen) are visible as yellowish blobs over the central retina (macula). The light sensitive tissue becomes distorted as it’s sitting on a wobbly bed, so the vision becomes distorted, too. This starts off an inflammatory process, causing damage to the cells. The build-up of waste material also creates a barrier so that the normal exchange of nutrients, and the normal functions can’t occur properly. The increased distance between the cells and the blood supply also means that less oxygen can get to the tissues, so more damage occurs. We know that excessive blue and UV light, including white LEDS and fluorescent lights can be damaging. AREDS 2 vitamins are recommended in patients with intermediate dry AMD. Smoking is harmful and excessive weight also.