Age-related macular degeneration is the leading cause of irreversible legal blindness among Australian adults. Unfortunately, this disease currently has no cure, but there is research underway. Current management strategies are aimed at slowing the progression of macular degeneration and preserving the remaining vision. Learning how to recognise macular degeneration symptoms can help you to seek attention from an eye doctor quickly.
What is Age-Related Macular Degeneration?
The macula is an anatomical part of your retina, the sensory tissue lining the inside of your eye. It’s responsible for your central sight, as well as colour discrimination and discerning fine detail. You use your macula for a vast number of tasks, including reading, writing, recognising faces, and even examining the food on your plate before eating it. Age-related macular degeneration symptoms can be devastating because of how much we rely on the macula for everyday activities.
Your eye doctor divides age-related macular degeneration into two broad categories: the dry or atrophic form and the wet or neovascular form.
Dry macular degeneration is further divided into progressive stages – early, intermediate, or late, though some clinicians may use different grading systems. During the early and intermediate stages, metabolic waste material accumulates beneath the retina. Your eye doctor can see this as yellowish deposits, known as drusen, on an examination. The build-up of drusen is eventually toxic to the overlying retina and photoreceptor cells, and so the retina undergoes atrophy as the cells deteriorate. Late-stage dry macular degeneration occurs when there is widespread atrophy.
Wet macular degeneration is less common but can cause sudden and significant macular degeneration symptoms. During the wet form, abnormal, fragile blood vessels develop underneath the retina. These blood vessels can leak blood and fluid, which damages the overlying cells of the macula. Any stage of the dry form of macular degeneration can deteriorate into the neovascular form.
It is not inevitable for age-related macular degeneration to progress all the way to the late-stage dry form or the wet form. Some people never move past the early or intermediate stages. It is also possible for one eye to have a more advanced disease than the other.
Recognising Macular Degeneration Symptoms
The symptoms of macular degeneration are not unique to this disease. However, it’s important not to dismiss any visual disturbances as age-related macular degeneration is not a normal part of ageing, and there are treatments your eye doctor can offer you.
In the early and even intermediate stages of dry age-related macular degeneration, you may not be aware of any symptoms or changes to your sight. Some people at the intermediate stage may notice some subtle changes, such as not being able to focus as clearly or having increasing difficulty in dim light. If you develop particularly large drusen, this can distort the retina above the deposits. This means that straight lines or edges can appear curved or wavy.
As the disease advances and more light-sensing photoreceptors become damaged, you will become increasingly aware that your central vision is not as sharp. If you develop significant areas of retinal atrophy, you will find that there are some blank or missing spots in your central field of view. You may notice more distinct distortion to your sight as more drusen accumulate.
If ever you experience a sudden, severe loss of part of your sight, this could indicate wet macular degeneration and a retinal bleed. It may just be a small area of vision loss, or it can cover an extensive field. Sudden loss of part or all of your sight is always an emergency, and you should see an eye doctor immediately.
Diagnosis and Management of Age-Related Macular Degeneration
While your symptoms may offer a clue as to what is going on in your eyes, there are other diseases that can share similar symptoms. An examination and diagnosis of age-related macular degeneration can be performed by your local optometrist or eye doctor.
Your assessment will include:
- Measuring your visual acuity. This is achieved by reading letters of decreasing size on a chart. Knowing your visual acuity will help your eyecare practitioner to monitor the progression of the macular degeneration as well as give him or her an idea of your functional sight.
- Fundoscopy. This involves directly viewing the retina and the macula. Your eyecare practitioner will be able to see drusen, areas of atrophy, or any neovascular haemorrhages.
- Retinal photography. Although not crucial for the diagnosis of macular degeneration, this technology is useful for monitoring progression.
As mentioned earlier, at the moment, there is no cure for age-related macular degeneration. However, there are some interventions that can help to slow its progression. The most common recommendation for dry macular degeneration is nutritional supplementation. The AREDS2 formulation includes potent antioxidants such as lutein and zeaxanthin, which have been demonstrated to delay the progression of dry macular degeneration. However, the AREDS2 trial showed a response only from patients at certain stages of the dry disease, so it’s best to check with your eye care practitioner before purchasing macula supplements.
For wet age-related macular degeneration, eye injections of a drug called anti-vascular endothelial growth factor (anti-VEGF) can be very effective at causing neovascular blood vessels to shrink and regress. In fact, a few studies have even found that there can be some gains in the visual acuity chart after anti-VEGF injections. There are several different types of anti-VEGF drugs available, and new ones are often being developed and approved. Anti-VEGF injections may be administered at regular intervals over a prolonged period of time, or your eye doctor may recommend a “treat and extend” approach, where the interval between each treatment is extended as far as is safe.
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Note: Any surgical or invasive procedure carries risks. Before proceeding, you should seek a second opinion from an appropriately qualified health practitioner.
Classifying age-related macular degeneration.
Age-related macular degeneration (AMD).