What is Macular Degeneration?
Macular degeneration, commonly referred to as Age Related Macular Degeneration (ARMD), is a condition that affects a person’s central vision, and the area affected is called the Macula. Cases are typically seen in people aged 50 years and older, and it is the most common cause of vision impairment in this age group. ARMD can cause loss of central vision and possible distortion, making straight lines appear bent, and letters or numbers jumbled when reading. Peripheral vision usually remains unaffected in cases of ARMD.
There are two main types of ARMD:
In dry ARMD, a gradual breakdown of the light-sensitive photoreceptors located at the macula occurs. Dry ARMD tends to progress gradually and often both eyes are affected.
The symptoms can include:
- Increased blur when reading
- Need for increased lighting when reading or doing close work
- Difficulty adjusting to low light levels
- Reduced intensity of or brightness of colours
- Difficulty recognising faces
Wet (Neovascular) ARMD
The cause of Wet ARMD is due to the abnormal blood vessels which start to grow under the macula. These new blood vessels are highly fragile and will leak blood and fluid. Unlike dry ARMD, damage to the eye progresses rapidly. Wet ARMD is a treatable condition, however, early detection is crucial for stabilising vision.
The symptoms of wet ARMD include:
- Distortion of printed words
- Distortion of straight lines (often will appear wavy), and is most clearly detected with an Amsler grid.
If you notice any sudden distortion in your vision, please contact us at the Eye Specialist Institute immediately.
Can dry ARMD turn to wet AMD?
Yes, dry ARMD can potentially cause loss of vision either by turning into wet ARMD or by causing extensive damage to the photoreceptors (this is known as geographic atrophy). There is no way to tell if/when dry ARMD will progress into wet ARMD.
Who is at risk of ARMD?
Anyone can develop muscular degeneration but a number of factors place people at greater risk:
Controllable risk factors
- Smoking – smokers have a 6x greater risk of developing ARMD.
- Nutrition – A diet high in lutein and omega-3 fatty acids found in fish can reduce the risk of ARMD.
- Obesity- Being severely overweight increases the chance of early ARMD progressing into severe cases of ARMD.
- Sun Exposure- Excessive UV exposure can increase the risk of ARMD.
Uncontrollable Risk Factors
- Genetics- specific genes have been associated with increased ARMD risk. People with a family history of ARMD are 4x more likely to develop late stage ARMD.
- Gender- ARMD is more common in females than males.
- Light skin/eye colour-People with fairer complexions and lighter eye colours are more at risk of getting ARMD than those with darker skin/eye colour.
- High long-sightedness
How is ARMD diagnosed?
ARMD can be detected via a number of methods:
- Eye Examination – Regular screening examinations with us at the Eye Specialist Institute will ensure early signs of ARMD to be detected. Testing may include:
- Visual Acuity – a measurement of vision on a letter chart
- Amsler Grid – an assessment of central distortion (e.g. lines being faded, broken or wavy).
- Retinal examination – a detailed examination of the macula will be conducted. In cases of early dry ARMD, there is often small yellow spots on the surface of the macula which is the build-up of metabolic waste.
Optical Coherence Technology (OCT)
Optical coherence tomography (OCT) is a non-invasive imaging test which uses light waves to detect areas of macular thickening or thinning, as well as the presence of abnormal blood and fluid under the macula, as seen in wet ARMD. OCT is also helpful in monitoring the treatment of wet ARMD.
During this procedure a fluorescein dye (vegetable based) is injected into a vein in the arm, the dye then travels through the circulatory system to the blood vessels in the eye. From here a series of photographs are taken as the dye passes through the blood vessels in the retina. Any signs of abnormal vessels will appear as a white patch on the photographs taken. Fluorescein Angiography is essential in both diagnosing and ruling out cases of wet ARMD, and it can also be used to detect changes in the macular pigment caused by dry ARMD.
What treatments are available for Dry ARMD?
The most common treatment available for wet ARMD is anti-VEGF therapy. This consist of administering a drug to shrink the abnormal blood vessels and dry up the excess macular fluid. These drugs are called anti-VEGF, and they block the effects of vascular endothelial growth factor (VEGF) a chemical in the body responsible for the formation of abnormal blood vessels found in cases of wet ARMD. By blocking VEGF in the eye, these agents work to stabilise and prevent vision decline. Anti-VEGF therapy is a breakthrough in wet ARMD treatment and makes it possible to prevent further vision loss in 95% of macular degeneration patients as well as improve 40% of patient’s vision.
There are numerous anti-VEGF drugs available and the Eye Specialist Institute uses (list of anti-VEGF drugs). The anti-VEGF treatment is administered via an injection into the eye after it has been numbed with a local anaesthetic. The initial treatment of three injections are what is required in order to stabilise the wet ARMD – this step is called Induction Therapy. From here maintenance therapy will subsequently be required every 4-12 weeks to retain vision. It is important to remember that early detection and intervention are crucial, and will provide patients suffering with wet ARMD, who undergo regular treatment, a higher chance of retaining good vision.