Age-related macular degeneration (AMD) is the leading cause of irreversible central vision loss in adults over the age of 50 worldwide — and in Singapore, rates are significant given the ageing population and high prevalence of AMD risk factors including smoking, hypertension, and a diet low in protective nutrients.
AMD affects the macula, the small, specialised region at the centre of the retina responsible for the sharp, detailed vision needed to read, recognise faces, drive, and perform close work. When the macula deteriorates, the centre of the visual field becomes blurred, distorted, or lost — though the peripheral (side) vision remains intact. AMD never causes total blindness, but its effect on central vision can be profoundly disabling.
The critical message about AMD is this: early stages cause no symptoms, wet AMD causes rapid vision loss that is reversible if treated urgently, and treatment has transformed the outlook for patients with wet AMD from near-certain severe vision loss to vision preservation and partial recovery.
What Is the Macula?
The retina is the light-sensitive layer at the back of the eye that converts visual images into nerve signals sent to the brain. The macula is a small oval region at the centre of the retina, approximately 5 mm in diameter, containing the highest concentration of photoreceptor cells (particularly cones) in the eye.
The macula is responsible for the central 20 degrees of our visual field — the sharp, high-resolution central vision we use for reading, threading a needle, recognising expressions, and any task requiring precise visual detail. The surrounding retina provides peripheral vision but cannot compensate for macular loss in tasks requiring fine detail.
In AMD, cells in and around the macula — including the retinal pigment epithelium (RPE) and photoreceptors — progressively degenerate. Waste products accumulate (forming drusen), blood vessels become abnormal, and the macula loses its ability to function normally.
Symptoms of AMD
AMD is insidious in its early stages — early and intermediate AMD frequently cause no symptoms at all, and the first symptom may be noticed only when the other eye is covered. By the time symptoms are noticed, significant damage to the macula may already have occurred.
Early warning signs
- Mild blurring or haziness in the central visual field
- Difficulty reading in dim lighting — needing brighter light for the same reading task
- Mild distortion of straight lines — door frames, ruled lines, or text appearing slightly bent
- Colours appearing less vivid or slightly washed out
Symptoms of advanced AMD
- A dark, grey, or blurry spot at the centre of vision that does not move with eye movement
- Significant distortion — straight lines appearing markedly wavy (metamorphopsia)
- Central blank area (scotoma) making faces, text, or fine detail difficult or impossible to see
- Difficulty recognising familiar faces at normal distances
- Inability to read standard print without magnification
Symptoms requiring urgent assessment
- Sudden onset or rapid worsening of central vision distortion
- A new dark spot or shadow appearing in central vision
- Straight lines that were previously slightly wavy becoming markedly distorted overnight or within days
Any sudden change in the pattern of AMD symptoms — particularly in a patient with known AMD — should be assessed urgently, as it may indicate conversion to wet AMD. Wet AMD that is treated within days of onset has significantly better visual outcomes than disease treated weeks later.
Risk Factors for AMD
Several factors increase the risk of developing AMD or accelerating its progression. Some are modifiable — and modifying them makes a meaningful difference to risk.
Non-modifiable risk factors
- Age: The most significant risk factor; AMD is rare before 50 and rises steeply with each decade thereafter
- Genetics: A family history of AMD significantly raises individual risk; the CFH and ARMS2/HTRA1 gene variants are strongly associated with AMD susceptibility
- Race: AMD is more common in Caucasian and Asian populations than in individuals of African ancestry
- Sex: Women have a slightly higher lifetime risk of AMD, partly due to longer life expectancy
Modifiable risk factors
- Smoking: The most powerful modifiable risk factor; smokers have 2–4 times the risk of AMD compared to non-smokers. Former smokers retain elevated risk for years after cessation.
- Cardiovascular risk factors: Hypertension, high cholesterol, and atherosclerosis are associated with increased AMD risk
- Obesity: Elevated BMI correlates with AMD risk, particularly progression from intermediate to advanced AMD
- Diet low in antioxidants: Insufficient intake of lutein, zeaxanthin, omega-3 fatty acids, and vitamins C and E
- Prolonged ultraviolet (UV) light exposure without eye protection
Living with AMD: Protecting and Maximising Your Vision
- Never miss a monitoring appointment: AMD can change rapidly and asymptomatically between visits
- Check the Amsler grid in each eye daily and contact your ophthalmologist promptly if new distortion appears
- Protect both eyes: AMD can affect one eye initially, and the other eye is at elevated risk
- Stop smoking: The single most impactful lifestyle intervention for AMD progression
- Take AREDS2 supplements if prescribed: Do not substitute with general multivitamins
- Wear wraparound sunglasses with UV400 protection in outdoor environments
- Maintain cardiovascular health: Blood pressure and cholesterol management protects retinal vasculature
- Eat a diet rich in dark leafy greens (kale, spinach), oily fish (salmon, sardines), and coloured vegetables
- Consider a low vision assessment if AMD is affecting reading, work, or daily activities — do not assume nothing can help
How is AMD Diagnosed?
AMD diagnosis requires a comprehensive eye examination. Several tests are used, each providing different information about the macula's structure and function. Early AMD may be found at a routine eye check in the complete absence of symptoms.
- Visual acuity test: Measures central vision using an eye chart. It provides a baseline and monitors changes over time, although early AMD may not affect vision.
- Dilated fundus examination: Eye drops widen the pupils so the retina and macula can be examined for signs of AMD, such as drusen, pigment changes, or bleeding.
- Amsler grid test: A simple grid used to check for distorted or missing areas in central vision. It can be used in the clinic or at home to monitor AMD.
- Optical coherence tomography (OCT): The most important test for AMD. It creates detailed images of the retina to detect drusen, retinal damage, fluid, and changes associated with dry or wet AMD. It is also used to monitor treatment.
- Fluorescein angiography (FFA): A dye is injected into a vein to highlight blood vessels in the retina. It helps detect leaking abnormal blood vessels in wet AMD and guides treatment.
- Indocyanine green angiography (ICGA): A special dye test that images deeper blood vessels beneath the retina. It helps identify certain types of wet AMD that may require different treatment.
