Understanding Macular Degeneration: Types, Risks, Diagnosis, and Treatment
Macular degeneration is a leading cause of vision loss in individuals that are aged 50 and older which explains why it's commonly known as AMD (age-related macular degeneration). It affects the macula, the central part of your retina responsible for sharp, central vision which is crucial when it comes to tasks like reading, driving, recognising faces, etc. In this article you will discover the two types of AMD, who is at risk, how it is diagnosed and potential available treatment options.
Types of AMD
There are two primary forms of macular degeneration: dry AMD and wet AMD.
Dry AMD: This is the most common form of the disease, dry AMD affects approximately 85-90% of those with the condition. It occurs when the macula's cells start to break down, leading to the thinning of the macular tissue. As a result of this thinning, yellow deposits called drusen form under the retina, which then ultimately cause a gradual loss of central vision. The progression of dry AMD is typically slow, and as it progresses the loss of vision increases until all vision may be lost.
Wet AMD: Accounting for about 10-15% of AMD cases, wet AMD is no less severe than its dry counterpart. It develops when abnormal blood vessels grow beneath the retina, leaking blood and fluid into the macula. This leakage distorts your central vision and can lead to a very quick and very severe vision loss. Without treatment, wet AMD can cause irreversible damage to the macula.
Dry macular degeneration can lead to the wet form, with about 10% of patients affected. These people comprise the vast majority of patients who experience serious vision loss.
It’s possible to have both dry AMD and wet AMD at the same time, and can be present in either one or even both of your eyes.
Who Is at Risk for AMD?
Several factors can increase your risk of developing this unfortunate disease. These include:
• Age: AMD is more common in individuals aged 50 and older, with the risk increasing as you age.
• Genetics: A family history of AMD increases the likelihood of you developing the condition.
• Race: Caucasians with light coloured eyes are more likely to develop AMD when compared to other racial groups.
• Smoking: Smokers are at a higher risk of AMD, as smoking damages the retina and at the same time also decreases the blood flow to your eyes.
• Obesity: Being overweight can increase the risk of AMD, particularly when paired with an unhealthy diet and a lack of exercise.
• Diet: A diet that is high in saturated fats and low in antioxidants and essential nutrients can be a contributor to the development of AMD.
• High blood pressure: Uncontrolled hypertension can increase the risk of AMD by causing damage to the blood vessels in your retina.
• High cholesterol levels: high levels of plasma HDL-C are associated with an increased risk for advanced AMD in European and Asian populations.
An eye Optometrist can diagnose AMD during your regular eye exam and may also carry out some more specific tests, which may include:
• Visual acuity test: This test measures the sharpness of your vision at different distances.
• Dilated eye exam: By dilating the pupils, an Optometrist can examine your retina and optic nerve for signs of AMD and / or any other eye conditions.
• Amsler grid test: This test can in fact detect any distortion or waviness whatsoever in your central vision, which may indicate the presence of AMD. Also, there are two free apps for your phone that can help you when it comes to monitoring your AMD, not of course as a direct replacement for your Optometrist.
• Optical coherence tomography (OCT): This imaging technique provides high-resolution, cross-sectional images of your retina, thus allowing an Optometrist to detect and measure any retinal abnormalities.
• Fluorescein angiography: Your Optometrist will refer you to an ophthalmologist for this test. In this test, a fluorescent dye is injected into the bloodstream to visualise the blood vessels in the retina and identify any leakage or abnormal growth associated with wet AMD.
While there is currently no cure for AMD, various treatment options can help slow the progression of the disease and preserve vision.
Dry AMD treatment: No specific treatment is available for dry AMD; however, by adopting a healthy lifestyle, including a nutrient-rich diet, regular exercise and not smoking, you can help slow the progression of the disease. In some cases, a high-dose formulation of antioxidants and zinc, known as the Age-Related Eye Disease Study (AREDS) formula may be recommended to slow the progression of dry AMD and reduce the risk of developing wet AMD.
With the AREDS study, it was found that the 5-year risk of the intermediate disease progressing to late disease was reduced by 25 percent with daily supplementation. The original AREDS multivitamin formula used in the study has been modified in the meanwhile, renamed as AREDS2 and now contains:
• 500 mg of vitamin C
• 400 IU of vitamin E
• 80 mg of zinc
• 10 mg of lutein
• 2 mg of copper
• 2 mg of zeaxanthin
Wet AMD treatment: Several treatments are available for wet AMD, aiming to halt or slow the growth of abnormal blood vessels and limit vision loss which include:
• Anti-vascular endothelial growth factor (VEGF) injections: These medications, injected directly into the eye help block the growth of abnormal blood vessels and reduce any leakage. Regular injections may be required to maintain the treatment's effectiveness.
• Photodynamic therapy (PDT): During PDT, a light-sensitive drug is injected into your bloodstream, which is then activated by shining a specific wavelength of light into the eye. This process damages the abnormal blood vessels without harming any of the surrounding tissue.
• Laser photocoagulation: A high-energy laser is used to destroy abnormal blood vessels, preventing further leakage and vision loss. However, it can also damage healthy tissue and is less commonly used today due to the availability of less invasive treatments like anti-VEGF injections (described above).
Macular degeneration is a prevalent cause of vision loss among older adults. Understanding the two types of AMD, dry and wet, along with their risk factors can help individuals take preventative measures and try to seek an early diagnosis. Although sadly there is currently no cure for AMD, the good news is that there are a range of treatments that can slow down its progression and help maintain your vision.
One important step you can take is to keep up with your routine eye check-ups and seek advice from an eye care specialist if you notice any alterations in your vision, particularly if you have any of the increased risk factors mentioned above in this article.
Author: John Dreyer Optometrist Bsc(Hons), MCOPTOM, DipCLP
Created: 4 Apr 2023, Last modified: 13 Apr 2023