Almost two million people in the UK live with sight loss, with around 360,000 registered as blind or partially sighted. Age-related macular degeneration (AMD) is one of the most common causes of blindness in the UK and the leading cause of sight loss in those aged 55 and over.
Raising awareness of the signs and symptoms of AMD can help people get the treatment they need, while continued research and innovation will hopefully someday prevent blindness caused by AMD. Here we’ll explore how AMD presents, what treatments are available today and what treatments are on the horizon.
AMD refers to damage caused to the macular, the central part of your retina, which is a light-sensitive layer of tissue at the back of your eyes that allows you to see. The macular is essential for your central vision ie your ability to see things directly in front of you, such as when reading, driving or performing any number of everyday tasks.
As the name suggests, AMD causes increasing damage to your macular with age, through general wear and tear. This causes a loss of your central, detailed vision, whether you’re looking at something close-up or far away. Meanwhile, your peripheral (side) vision will remain normal.
There are two types of AMD — dry AMD and wet AMD.
Dry AMD is the most common type of AMD, accounting for around 80% of AMD cases. In dry AMD, part of your macular becomes thinner and clumps of a substance called drusen collect under your retina. Over the years, as your retina wears out, you will lose vision in patches, with the patches gradually getting larger. These patches can join together over time causing a large central blind spot.
Some people with dry AMD will go on to develop a more aggressive type of AMD called wet AMD. Wet AMD accounts for around 20% of all AMD cases. Dry AMD becomes wet AMD when new blood vessels grow under the retina. These blood vessels do not grow properly and are leaky. As they leak blood and other fluids, they damage and scar the macular. Sight loss from wet AMD occurs faster than with dry AMD.
There is currently no treatment for dry AMD. However, vision and lifestyle aids can help manage your symptoms, such as magnifying glasses, brighter lighting, large print books and various digital apps.
Wet AMD is currently treated with injections of anti-VEGF (vascular endothelial growth factor) drugs into the eyeball every four to eight weeks. These drugs help reduce the number of abnormal blood vessels that grow under the retina and slow any leaking from them.
In the early stages of AMD, you may notice distortions in your vision, such as straight lines appearing bent or letters appearing blurry. You may find it difficult to adjust to low lighting and that you often need brighter lighting. As the condition progresses, you may find it difficult to recognise faces.
If you have wet AMD, you may additionally notice a blurred or dark spot in your field of vision and your vision becoming hazy.
Huge advances have been made in the management of wet AMD. Many new treatments are showing promising results in clinical trials. This includes longer-lasting anti-VEGF injections so patients don’t have to come in for their injections so often.
With the same goal in mind of fewer visits for injections, port delivery systems are also in development. This involves implanting a reservoir device into the eye that holds a greater volume of medication. This medication is then delivered in a controlled and continuous way for several months before it needs refilling by a doctor.
Gene therapy is also being investigated as a way to mimic the action of anti-VEGF medication, ie blocking the activity of VEGF in the eyes, using a harmless virus that carries an anti-VEGF gene.
Dry AMD is proving harder to treat. However, research continues into how to slow down or prevent dry AMD progressing. Unfortunately, many of these potential treatments involve injections into the eyeball that slow down dry AMD at the expense of increasing the risk of wet AMD.
An alternative approach, currently under investigation, is photobiomodulation (PBM), a type of light therapy that aims to change the way the cells in the retina work.
Ageing is the main risk factor for AMD and consequently, there is no way to reduce your risk of developing AMD. However, you can reduce your risk of it more rapidly getting worse by following a healthy diet and not smoking.
If you already have intermediate stage AMD, vitamin supplements containing AREDS or AREDS2 formulas, which are available at most chemists, may be of some benefit.
If you have noticed symptoms of AMD, such as blurred vision, straight lines appearing bent and needing brighter lights to see well, it is important to see an optician within two weeks, especially if you are aged over 55. For wet AMD, in particular, early diagnosis and treatment can help you maintain your vision for longer.
Let your optician know about your symptoms and concerns, and ask for an Optical Coherence Tomography (OCT) scan. This will allow them to see your retina in more detail. Your symptoms may be caused by something other than AMD but in either case, a diagnosis and prompt treatment can help improve your quality of life.
Depending on the results of your OCT scan and eye examination, your optician may refer you to an ophthalmologist (a doctor specialising in treating eye conditions). You may need further tests and your ophthalmologist will discuss your treatment options.
Professor Ben Burton is a Consultant Ophthalmologist at Spire Norwich Hospital and James Paget University Hospitals NHS Foundation Trust, specialising in cataract surgery and the treatment of retinal diseases, including age-related macular degeneration (AMD), diabetic retinopathy and retinal vein occlusions. He is an active member of the research community, specifically involved in clinical trials for new treatments for wet AMD.