Age-related Macular Degeneration

Age-related Macular Degeneration (AMD) is one of the leading causes of blindness affecting those 50 years or older. AMD is a chronic eye condition that often results in vision loss in the centre of the visual field because of damage to the macula (the central part of the retina).  Some of this vision loss may be permanent or irreversible. 

This condition may make it difficult for the patient to read, recognise faces or drive safely, because we rely on our central vision for these tasks. However, peripheral vision remains intact for most people, allowing them to remain independent for most daily activities.

In early Age-related Macular Degeneration (AMD), the impact on vision is generally mild or even non-existent. However, as the disease progresses, symptoms may include:

• Blurring of central vision (may be gradual or rapid in onset)
• Shadows or missing areas of vision
• Distorted vision (e.g. straight lines appear wavy)
• Problems discerning colours, especially differentiating between similar colours
• Slow recovery of visual function after exposure to bright light
• Loss of contrast sensitivity (ability to tell different levels of brightness apart)
  

So far, there are no treatments that have been proven to be highly effective in preventing Age related Macular Degeneration (AMD). Studies have shown that smokers are more than four times more likely to develop "wet" or advanced Age-related Macular Degeneration (AMD) than non-smokers. Therefore, reducing or stopping smoking can reduce the risk of AMD.

A particular combination of supplements and vitamins, commonly referred to as the "AREDS2" formulation, has been shown to reduce the risk of developing the advanced form of AMD.  However, the reduction in risk was only about 25% over 5 years, and this was only proven for some patients with high risk, and not all patients.  It would be best to consult your eye doctor on whether these supplements will be beneficial for you.

The best way to avoid permanent vision loss is with prompt eye examination and diagnosis by your eye doctor. Early diagnosis improves the chances of treatment success.

A screening tool, the Amsler grid, may help to detect subtle changes in your vision. You can monitor your vision daily by looking at an Amsler grid. If you do not have access to the Amsler grid, you may also use items that you see daily such as bathroom tiles or window panes with straight lines, both horizontal and vertical.

You should also eat a balanced diet that includes leafy green vegetables, stop smoking, and protect your eyes from UV light with protective sunglasses or brimmed head gear.

Amsler Grid Chart

What causes Age-related Macular Degeneration (AMD)?

Age-related Macular Degeneration (AMD) occurs in "dry" and "wet" forms. 90% of AMD patients suffer from the "dry" form. Patients with dry AMD may have no symptoms, or may experience slow progressive loss of central vision. Vision is affected as the light-sensitive cells in the macula slowly break down with age. Wet AMD, also known as exudative or neovascular AMD, is caused by the growth of small, abnormal blood vessels under the retina in the macula. Wet AMD usually arises from pre-existing dry AMD. These abnormal blood vessels leak blood, fluid, lipids and protein, resulting in disruption of the normal structure of the retina. If it is not treated, scar tissue tends to form under the macula, resulting in permanent central vision loss. The "wet" form of AMD is more aggressive, and often results in severe visual loss within a short period of time.

What puts me at risk of Age-related Macular Degeneration (AMD)?

Your risk increases with:

• Age - a 1997 study showed that one in four people aged 60 and above suffer from the condition in Singapore
• A positive family history
• Smoking
• Obesity
• Cardiovascular diseases
  

The early stages of AMD usually start without symptoms. A comprehensive dilated eye examination is needed to diagnose AMD. The eye examination may include the following:

• Amsler Grid
  Your ophthalmologist may ask you to look at an Amsler grid. Changes in your central vision may cause the lines in the grid to disappear or appear wavy, a key sign of AMD. This is also used to monitor patients at home for progression or recurrence of disease.
  

Hold the Amsler grid below at eye level at a comfortable reading distance. If you wear reading lenses, wear them during this test. Cover one eye at a time and focus on the dot in the centre. If you see wavy or fuzzy lines, or if certain squares are missing or appear blurred, you may be displaying symptoms of Age-related Macular Degeneration (AMD).

For dry Age-Related Macular Degeneration (AMD), there is currently no known treatment. Some patients may benefit from the "AREDS2" formulation of supplements and vitamins, in terms of reducing the risk of developing advanced AMD. It would be best to consult your eye doctor on whether these supplements will be beneficial for you. Early detection of conversion to the wet type is also important for better preservation of vision. 

If you have been diagnosed with wet Age-Related Macular Degeneration (AMD), treatment is usually necessary as the condition may worsen over the next few weeks and lead to irreversible vision loss. While treatment can anaesthetise vision, the degree of improvement varies in individual patients, depending on how early the disease is detected, and response to treatment.

Intravitreal injections (medications injected into the eye)

Currently, the most common form of treatment for wet AMD is with medications injected into the eye. Bevacizumab (Avastin)*, ranibizumab (Lucentis) and aflibercept (Eylea) are some medications that are frequently used to treat wet AMD as they block the growth of abnormal blood vessels. Other new medications are also in development, and may be available soon. The injection procedure can be performed safely after the eye has been anaesthetised with eye drops. You may experience some mild discomfort after the injection. *Use of Avastin in the eye is off-label, but is safe and well-accepted by all public hospitals and institutions in Singapore for the treatment of wet AMD.

Treatment effect depends on the exact type of AMD you have, and does vary from person to person. In general, the effect of each injection would usually last for a few weeks to months, and in most cases, multiple injections are required over a period of time to adequately control the condition. Clinical studies have suggested that at least 12 to 14 injections may be required over a two-year period to control the disease. During this time, your eye condition will be reviewed frequently. Your ophthalmologist will also need to repeat the OCT scan at most visits, and the angiogram, depending on your response.

Illustration: Intravitreal Injections
of Anti-VEGF Agents

Other treatment options (usually used in combination)

In some selected cases, other forms of treatment, with or without injections, may also be recommended by your ophthalmologist. For example, photodynamic therapy (PDT) uses a non-thermal "cold" laser together with an intravenous medication (verteporfin) to reduce leakage and seal up abnormal blood vessels. Sometimes, laser photocoagulation may be used with a thermal "hot" laser to seal up the abnormal blood vessels.