Age Related Macular Degeneration

There are two main types of Age Related Macula Degeneration:

ARMD/Figure 1

  1. ‘Dry’ type of Age Related Macula Degeneration (please refer to Fig 47)
  2. ‘Wet’ type of Age Related Macula Degeneration (please refer to Fig 48)

The ‘dry’ and ‘wet’ types of Age Related Macula Degeneration look very different.

The ‘dry’ variety is characterised by ‘round deposits’ (called drusen) which are collections of degenerative material and ‘atrophic retina’ which is retina that is ‘thinned out’.

The ‘wet’ variety is characterised by abnormal blood vessels which grow beneath the retina and bleed or leak into that space. These abnormal blood vessels form what is called a choroidal neovascular membrane (CNVM).

The ‘dry’ type of ARMD usually presents with a slow, progressive loss of vision. The vision usually is quite stable and deteriorates slowly to poor levels. The ‘wet’ type of ARMD may present with a rapid onset of drastic loss of vision. This usually occurs when the abnormal blood vessels bleed beneath the retina.

Unfortunately, the majority of patients with legal blindness are due to the ‘wet’ type of ARMD. (The ‘wet’ type of ARMD constitutes only 10% of all types of ARMD but is responsible for 90% of legal blindness due to ARMD.)

 

Qn 1: Is Age Related Macula Degeneration treatable?

The diagnosis of ARMD is usually straightforward – the patient is elderly and has the clinical features of ARMD in both eyes.

  1. The ‘dry’ type of ARMD, for the sake of simplicity, can be divided into the ‘atrophic’ type and the ‘drusenoid’ type.

    For the ‘drusenoid’ type of ARMD, the Age Related Eye Diseases study (AREDS) found that for certain advanced stages of the ‘drusenoid’ type of ARMD, daily consumption of antioxidants such as Vitamin C (500mg), Vitamin A (15mg) and Vitamin E (400 IU), together with Zinc 80mg and Copper oxide 2mg, reduced the risk of progression for advanced ARMD by 25% over 7 years. Patients are also advised to stop smoking as smoking is a major risk factor for ARMD.

    CONCLUSION ON TREATMENT FOR DRY ARMD

    1. Stop smoking! Smoking is a major risk factor for ARMD progression and development
    2. Have a healthy balanced diet which contains adequate amount of antioxidants
    3. Laser treatment for ‘drusenoid’ ARMD has no benefit
    4. If you are found to have dry ARMD, especially the advanced stage of dry ARMD, your retinal surgeon will probably advise you to take antioxidant supplements similar to the AREDS formulation and monitor your vision with an Amsler grid.
  2. There exists treatment for the ‘wet’ type of ARMD. However, the decision to treat the ‘wet’ type of ARMD depends on the vision of the eye, the location and the size of the abnormal vessels (choroidal neovascular membrane).

Once the diagnosis is made of a ‘wet’ type of ARMD, in order to determine whether the ARMD should be treated, the patient must be subjected to a test called a fluorescein angiogram (FFA) and if the equipment is available, an indocyanine green angiogram (ICG).

The fluorescein angiogram (Fig 49, 50) is the ‘gold standard’ test for ARMD as it provides valuable information about the size and location of the abnormal vessels (choroidal neovascular membrane).

The fluorescein angiogram (FFA) involves injecting a dye into the veins of the arm. This dye is unique in that it has the property of fluorescence when blue light shines on it. The dye will enter the circulation and passes into the blood vessels of the eye. Once in the eye, it will enter all the blood vessels, including the abnormal blood vessels, and blue light will cause it to fluoresce and reemit green light. The images of the blood vessels can be then captured on film or on video. By examining the images captured, one can determine the size and location of the abnormal blood vessels (CNVM).

Some patients may be allergic to fluorescein and are not suitable for this test.

The Indocyanine Green angiogram (ICG) (Fig 51, 52) is a test whereby indocyanine green dye is injected into the veins of the arm and special cameras are used to record the images of the blood vessels of the retina and choroid. The ICG test is useful as an adjunct to the fluorescein angiogram as it is able to visualise the abnormal choroidal blood vessels of the CNVM much clearer, even when there is some overlying subretinal blood. For certain types of ARMD such as Idiopathic Polyploidal Choroidovasculopathy (IPCV), the findings on ICG are quite characteristic and help in guiding the laser treatment. If a patient is allergic to iodine or seafood, then ICG is contraindicated.

ARMD/Figure 2
 

Proven treatments for the ‘wet’ type of Age Related Macula Degeneration are laser treatments and Vascular Endothelial Growth Factor inhibitors(anti- VEGF) drugs.

There are many different types of laser treatment that can now be used to treat the ‘wet’ type of ARMD:

  1. Focal ablation laser treatment where the laser is used to destroy the abnormal blood vessels directly by direct heat damage. However, this also means that the retina overlying the abnormal blood vessels is also completely destroyed. There will be a drop in vision corresponding to the area of the retina treated and if this part of the retina is located centrally at the fovea (which is responsible for clear vision), the patient will have an immediate drop in vision after treatment and will be very unhappy. Presently, focal ablation laser treatment is uncommonly performed by retinal surgeons due to better laser treatments such as PDT/TTT lasers (please refer to subsequent paragraphs b. and c.) and the emergence of new treatment options with Vascular Endothelial Growth Factor Inhibitors(anti-VEGF drugs—-please refer to subsequent paragraph d.). However, in a small subgroup of patients with ‘wet’ ARMD, retinal surgeons have classified them as Idiopathic Polyploidal Choroidovasculopathy (IPCV) — these patients may benefit from focal ablation laser treatment if the ‘hot spot’ (leakage point identified from Indocyanine Green angiography) falls outside the center of the macula and can be lasered safely.
  2. Photodynamic Therapy (PDT) is one of the latest treatment modalities. It involves injecting a special light sensitive dye (such as verteporfin) into the veins of the patient’s arm. After a short period of time, a laser using a certain wavelength of light will be shone into the patient’s retina where the abnormal blood vessels are. This special wavelength of laser light will activate the dye and cause very localised damage to the blood vessels and not damage the overlying retina. As a result, the patient’s vision is not affected. Treatment of Age Related Macula Degeneration with Photodynamic Therapy (TAP) study showed that for certain ‘wet’ types of ARMD, photodynamic therapy succeeded in destroying the abnormal blood vessels in a significant number of patients and prevented further deterioration of their vision. The FDA studies for PDT showed that 70% of treated patients had stabilization of their vision with treatment and 14% had visual improvement. Finally, an average total of 3.4 treatments were administered during the first year of follow up, and 2.1 treatments in the second year of follow up. Thus, an average total of 5.5 treatments were needed in the first two years to maintain stabilization of the disease or vision. Unfortunately, PDT treatment is not a cure and multiple treatments are needed to stabilize the vision in the majority of patients.
  3. Transpupillary Thermoplasty (TTT) is one of the latest form of laser treatment being studied for the treatment of the ‘wet’ type of ARMD. It basically involves shining a laser light of low intensity and at a certain wavelength onto the affected area of the macula. This low intensity laser light will not damage the overlying retina but is postulated to cause damage to the abnormal blood vessels in the underlying ARMD lesion. It does not involve injecting a special dye.
  4. Vascular Endothelial Growth Factor inhibitors (anti- VEGF) drugs. In the ‘wet type’ of Age Related Macula Degeneration, abnormal blood vessels grow underneath the retina. If the growth of these abnormal blood vessels could be stopped or retarded, the serious vision threatening complications such as subretinal haemorrhage/exudates can be prevented.
  5. Combination therapy of laser treatment and VEGF inhibitors(anti-VEGF drugs). Many retinal surgeons use a combination of both laser treatment and injecting VEGF inhibitors directly into the eye for the treatment of ‘wet’ ARMD. Theoretically, performing Photodynamic Therapy (PDT) first will cause the abnormal blood vessels underneath the retina to close up (in medical terms "to thrombose"). After a short period of time (usually a few weeks), the VEGF inhibitor is injected directly into the eyeball to prevent further growth of abnormal blood vessels and to reduce macula swelling(by reducing vessel leakage).

CONCLUSION OF TREATMENTS FOR ‘WET’ ARMD

  1. If you have ‘dry’ ARMD, it is important to stop smoking, take the recommended antioxidant formulation and monitor your vision daily with an Amsler chart. If there is any distortion or blurring of your eye with ‘dry’ ARMD, it is important for you to inform your retinal surgeon immediately. Early treatment for ‘wet’ ARMD may prevent or reverse the vision loss
  2. There are now proven treatment methods for ‘wet’ ARMD—-laser treatment and Vascular Endothelial Growth Factor Inhibitors (anti-VEGF drugs)
  3. Some surgeons will use both laser treatment and anti-VEGF injections in a combination treatment. Please discuss this thoroughly with your retinal surgeon. The better results of combination treatment as compared to either laser treatment or VEGF inhibitors alone have not been proven in a large clinical trial yet

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Qn 2: Can surgery be done for ARMD? What are the results of such surgery?

So far, the proven treatments for the ‘wet’ type of ARMD are laser treatment and Vascular Endothelial Growth Factor inhibitors (anti- VEGF drugs).

Due to the poor results of the Submacular Surgery Trials, most retinal surgeons still prefer the various laser treatment modalities (focal laser ablation, Photodynamic Therapy, Transpupillary Thermoplasty) or to inject VEGF inhibitors such as Lucentis (Ranibizumab), Avastin (Bevacizumab) or Macugen (Pegaptanib) directly into eyeballs with Age Related Macula Degeneration. Presently, many retinal surgeons use a combination of both laser treatment and VEGF inhibitors—-performing laser treatment first followed by a regimen of injecting VEGF inhibitors directly into the eyeball.

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Qn 3: I have poor vision due to Age Related Macula Degeneration. Will I go completely blind?

You will never go completely blind due to Age Related Macula Degeneration (ARMD). The peripheral vision will always be preserved, unless there are other diseases such as glaucoma present. In ARMD, the central vision is always affected, but the peripheral vision is almost uniformly spared. Hence, the patient may not recognise faces, see the numbers on the bus or read the newspapers, but the patient will always be able to dress, feed, clothe and walk about independently. There will be some disability as patients with significant loss of central vision will find difficulty in sewing, putting in eye-drops and finding small objects that they have dropped on the floor.

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Qn 4: I have lost central vision in one eye due to bleeding from the ‘wet’ type of Age Related Macula Degeneration. What is the risk that I may develop the same condition in my only good eye? Is there any chance of prevention?

Unfortunately, the fact that one eye has lost vision due to the ‘wet’ type of Age Related Macula Degeneration indicates that the risk of the same happening to the good eye (fellow eye) is higher. Several studies have shown that the risk to the fellow eye (the ‘good’ eye) is about 4 – 12% annually for the first 36 months. If the ophthalmologist finds large deposits in the retina (drusen) and pigmentary changes in the good eye, the risk of developing ‘wet’ ARMD changes is high.

The recent Age Related Eye Diseases Study (AREDS) found that the following will retard the progression of the condition:

  1. Stop smoking as this has been found to be a risk factor in several studies.
  2. Vitamins A, C, E and the essential minerals zinc and copper have been found to be of some benefit in slowing the progression of macular degeneration. The dosages of in the study were 500mg of Vitamin C, 400IU of Vitamin E, 80mg of zinc, 2mg of copper and 15mg of beta carotene. (Vitamin A).
  3. It is not proven but patients are advised to avoid overexposure to the ultraviolet sun rays by staying out of the sun or wearing protective sunglasses.

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