A blurry vision
Age-related macular degeneration does not cause complete blindness but it can make it harder to drive, see faces and do close-up work.
Age-related macular degeneration (AMD) is a common condition and is a leading cause of vision loss for those aged 50 and above. Though it does not cause complete blindness, it however makes it harder to drive, see faces and do close-up work such as cooking or fixing things around the house.
Ageless Online finds out more about this condition and what you need you need to know if you have AMD from Associate Professor Ian Yeo, deputy medical director and academic vice-chair (education), and senior consultant, Medical and Surgical Retina Department, Retina Service, Singapore National Eye Centre (SNEC):
What happens when one has AMD?
AMD causes damage to the central 0.5mm of the retina, also known as the fovea, and surrounding this central area is called the macula. This part of the eye gives us the ability to read, recognise faces and colours, and it is also the point that provides us with the quality vision which we take for granted. While the central vison may be lost in AMD, the peripheral vision remains intact in most patients, however the quality of the peripheral vision is noticeably poorer. AMD can occur in ‘dry’ (early) and ‘wet’ (late) forms.
Can you explain these forms and which is the most common?
- Dry AMD – About 90 percent of AMD patients suffer from this. Over time, light sensitive cells in the macula slowly degenerate due to wear and tear, resulting in a progressive loss of central vision. People with dry AMD may still be able see well if there are enough healthy photoreceptors still functioning. Changes in the eye, such as drusen (white lipid deposits under the retina) can only be picked up during a dilated eye examination.
- Wet AMD – Also known as exudative or neovascular AMD, it is caused by the growth of small, abnormal blood vessels that will leak resulting in blood and fluid disrupting the structure of the fovea and macula area. Left untreated, scar tissues form under the macula and central vision is permanently destroyed. Wet AMD may arise from pre-existing dry AMD and will result in advanced visual loss within a short period of time if undetected and promptly treated.
What are the symptoms and causes?
In early AMD, symptoms are generally mild or even non-existent. However, as the disease progresses, the following symptoms may present:
- Blurring of central vision.
- Shadows or missing areas of vision.
- Distorted vision.
- Problems discerning colours.
- Slow recovery of visual function after exposure to bright light.
- Loss of contrast sensitivity (ability to differentiate levels of brightness).
How is AMD diagnosed?
By the age of 40, you should start going for eye screening periodically, even if you do not show symptoms. The frequency of screening should increase with age and is dependent on your family history. Patients at risk (those with a positive family history) need to observe changes in their vision, as they are more susceptible to AMD – the onset tends to be earlier, and it is usually important for better preservation of vision.
Once a person is suspected or detected to have AMD, he or she needs to undergo a comprehensive eye examination for diagnosis and monitoring of condition. Screening is done with a dilated retinal examination or through retinal photography and/or Optical Coherent Tomography (special scan of the retina layers).
What are the treatments if one has AMD?
Although dry AMD is more common, there is no known treatment for it. Essentially the cells at or around the fovea dies off slowly. In wet AMD, long-term treatment may be required to adequately control the condition, which tends to be recurrent. Lifelong follow-up is needed.
Currently, the most common treatment is intravitreal injection of anti-VEGF (vascular endothelial growth factor) drugs. A needle is used to inject the drug directly into the white part of the eye beside the cornea. It is done as an outpatient procedure with varying frequency, from monthly to a few months apart, for maintenance.
Other treatment options include cold laser therapy (photodynamic therapy with visudyne) and a combination of anti-VEGF injections and laser therapy. While treatment can stabilise vision, the choice of drugs and degree of improvement depend on when the condition was diagnosed, size of damage and subtypes of AMD (e.g. polypoidal choroidal vasculopathy or PCV), as well as the response to the initial treatment.
It is important to note that both the injection process and drugs are generally safe, but they are not risk-free. This is because it is an invasive and repeated procedure, patients may worry about damaging the eye, infection and retinal detachment. The drugs have also been reported to cause strokes, heart attacks, and hypertensive episodes. However, the risk of these complications is less than one percent.
There are ways to optimise the patient’s eyesight and minimise the visual handicap so that he or she can continue to lead a fruitful life, even if the condition is beyond treatment. Through SNEC’s Low Vision Service and Seniors’ Eye Rehabilitation Programme (SEER), patients are advised on ways to cope with vision loss and utilise their remaining vision, as well as improve their quality of life with the help of low vision aids. SNEC is the only institution in Singapore that provides a vision rehabilitation programme. With guidance from fully trained clinicians and staff who are motivated to help, the patients are encouraged to overcome their challenges with positivity.
Can supplements help such as Vitamins C and E, lutein, zeaxanthin, zinc, and copper?
These supplements have been shown in studies to slow down the progression of dry to wet forms of AMD in patients with eyes at high risk. The ingredients in these supplements are also found in our daily diet. The ingestion of leafy greens, nuts and eggs also help in the same way. Note that these only help to reduce progression is some patients and does not halt progression. You should speak to your doctor to discuss with them if these supplements are suitable for you.
What is the outlook for those who have AMD?
If you are able to be seen and treated very early for wet AMD, the outlook is excellent. Often, the challenge is from patients who present wet AMD at a later stage. For dry AMD, we work with patients to optimise their remaining central vision with visual aids and many continue to live fulfilling lives with their remaining vision even when the dry AMD is advanced.
How can one prevent getting AMD?
One can reduce the risk of AMD or slow its progression in high-risk eyes by not smoking, avoiding exposure to second-hand cigarette smoke, maintaining a healthy weight, keeping blood pressure under control, and having a balanced diet.
(** PHOTO CREDIT: Unsplash/Jeffrey Riley)