AGE-RELATED MACULAR DEGENERATION
What is Age-Related Macular Degeneration?
Age-related macular degeneration (AMD) is a condition affecting the macula, the central part of the retina responsible for sharp, detailed vision used for reading, recognising faces, and driving.
AMD causes progressive changes to the macula that can affect central vision, while peripheral (side) vision is generally preserved.
AMD is broadly categorised into two types:
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DryAMD (non-neovascularAMD): the more common form, characterised by the gradual thinning of the macula and the build-up of small deposits called drusen beneath the retina. Dry AMD usually progresses slowly over years.
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Wet AMD (neovascularAMD): less common but more aggressive, occurring when abnormal new blood vessels grow beneath the retina. These vessels can leak fluid or blood, causing rapid and significant vision loss if untreated. Wet AMD can develop in an eye that previously had only dry AMD.
Age-Related Macular Degeneration (AMD) in Singapore
Symptoms of AMD
AMD often progresses gradually, and early stages may cause no noticeable symptoms. As the condition progresses, symptoms can include:
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Blurred or reduced central vision, while side vision remains normal.
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Distorted vision, where straight lines appear wavy or bent (similar to the distortion seen in epiretinal membrane, but caused by a different underlying process).
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A blind spot or dark area in the centre of vision.
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Difficulty recognising faces at a normal conversational distance.
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Colours appearing less vivid.
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Difficulty adapting to low light or needing more light for reading.
A sudden worsening of any of these symptoms, particularly a rapid increase in distortion or a new blind spot, can indicate a transition from dry to wet AMD and should be assessed promptly, as early treatment of wet AMD is associated with better outcomes.
Risk Factors for AMD
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Age: the risk ofAMD increases significantly after age 50 and continues to rise with age.
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Family history: having a parent or sibling with AMD increases personal risk.
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Smoking: one of the most significant modifiable risk factors, smokers have a substantially higher risk of developing AMD.
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Cardiovascular risk factors: high blood pressure and high cholesterol have been associated with increased AMD risk.
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Diet: diets low in certain nutrients (such as antioxidants and omega-3 fatty acids) have been associated with increased risk in some studies.
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Ethnicity: AMD is more common in certain populations, though it can affect people of all backgrounds.
How is AMD Diagnosed and Monitored?
Diagnosis and monitoring ofAMD typically involve:
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Dilated eye examination, to directly assess the macula for drusen, pigment changes, or signs of wet AMD.
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Optical coherence tomography (OCT): a non-invasive scan providing detailed crosssectional images of the macula, used to detect fluid associated with wet AMD and to monitor changes over time.
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Fundus photography, to document and track changes in the macula.
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Fluorescein angiography or OCT angiography, which may be used to assess the pattern and activity of abnormal blood vessels in wet AMD.
Patients with dryAMD, particularly with risk factors for progression, are often monitored periodically, sometimes with the use of a home monitoring tool (such as an Amsler grid) to help detect any sudden changes between clinic visits.
Management of Dry AMD
There is currently no treatment that reverses the changes of dryAMD, and management focuses on monitoring, risk reduction, and early detection of any progression to wet AMD:
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Regular monitoring, including OCT imaging, to detect early signs of progression.
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Nutritional supplementation: certain combinations of vitamins, minerals, and antioxidants have been studied for their role in reducing the risk of progression in intermediate AMD, and may be recommended based on the specific findings in your eyes.
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Smoking cessation, given its strong association with AMD progression.
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Management of cardiovascular risk factors, such as blood pressure and cholesterol
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For more advanced forms of dry AMD involving geographic atrophy, newer treatments are an active area of research and development, and their suitability is assessed on an individual basis
Treatment of Wet AMD
Wet AMD is primarily treated with intravitreal injections of anti-VEGF (anti-vascular endothelial growth factor) medications. These medications work by blocking the signal that causes abnormal blood vessels to grow and leak, helping to stabilise or, in some cases, improve vision.
Anti-VEGF Medications
Several anti-VEGF medications are available and used in clinical practice in Singapore, including ranibizumab, aflibercept, and faricimab, among others. Newer formulations with extended dosing intervals, and emerging delivery systems such as sustained-release implants, continue to be developed.
What is the Treatment Schedule Like for Wet AMD?
Treatment for wet AMD typically begins with a course of monthly injections to bring the condition under control, followed by a maintenance phase where the interval between injections may be extended based on how the eye responds, guided by regular OCT monitoring. Ongoing, long-term treatment is often required to maintain stability, as the underlying tendency for abnormal vessel growth does not resolve permanently with treatment.
