What is Age Related Macular Degeneration (AMD)?

Macular degeneration is the name given to a group of chronic, degenerative retinal eye diseases that cause progressive loss of central vision, leaving the peripheral or side vision intact.

Whilst the condition is usually related to ageing and most frequently affects people over the age of 50, it is also caused by genetic and environmental factors. Risk factors include age, family history, smoking, diet and lifestyle.

The disease affects a special layer of cells in the eye called the Retinal Pigment Epithelium (RPE). The role of the RPE is to nourish the retina and get rid of its waste products. It also acts as a barrier between the retina and the choroid.

Geographic atrophy or “dry” macular degeneration is a type of AMD that is caused by RPE cell death. When RPE cells do not function, the retinal cells above them are affected, leading to patches of ‘missing retina’. This is a slow form of the disease causing gradual loss of vision and accounts for 33% of all cases of late-stage AMD. Some cases of early or dry AMD can later develop the more aggressive wet form. It is important to report any sudden changes in vision to your eye specialist.

Wet AMD occurs when the RPE cells fail to stop choroidal blood vessels from growing under the retina. This growth is called Choroidal Neovascularization (CNV). The rapidly growing vessels are fragile and may leak fluid and blood under the retina, leading to scarring and vision loss. Wet AMD is the most severe form of the disease and visual changes are often sudden and severe.

Early in the development of AMD, people notice that they need a brighter light to read, faces can be harder to recognise and have difficulty with to glare or adjusting to dim lights (such as driving into an underground car park). In advanced AMD, abnormal blood vessels sprout under the retina causing distortion and blurred vision (“wet” AMD). Prompt diagnosis is essential to optimise the vision by commencing treatment with an anti-VEGF drug.

In some cases, progressive difficulty reading can be due to areas of retinal atrophy that have poor sensitivity around the area of sharp central vison. This is usually referred to as “dry AMD”. Currently, there is no treatment options for this form of AMD, however Retinology Institute is involved in geographic atrophy clinical trials that offer an alternative option for affected patients.

It is important to know that AMD is due to an inherited susceptibility. Preventative measures help slow down deterioration, but there is currently no cure the underlying disease.

In summary, the critical issues are:

Natural anti-oxidants:

The eye contains two agents to protect it from light induced damage – Lutein and Zeaxanthin.  These effective antioxidants filter out high energy blue light and protect the deep retinal layers.

  • Lutein: Best sources are green leafy vegetables (kale, spinach, broccoli, and romaine lettuce), corn, green peas and cabbage.  (If you are unable to eat green leafy vegetables due to medication or other reasons, Blackmores Lutein-VisionTM and Lutein DefenceTM contain extracts from the green leafy vegetables.  (One tablet twice a day is best).
  • Zeaxanthin: Whilst yellow vegetables (yellow capsicum, mango, corn) and orange juice are excellent sources, the most concentrated source of Zeaxanthin is goji berries. Egg yolks also have high concentrations of both Lutein and Zeaxanthin. Having six eggs per week has been shown to be beneficial to those with Macular Degeneration.

Other Important Dietary and Lifestyle Options

Fish

Omega 3 fatty acids have been shown to be the most powerful modifier of AMD. Oily, deep sea fish for e.g. tuna, mackerel, salmon and sardines is recommended twice per week. You may also take fish oil tablets and follow a diet low in saturated and trans-fats.

  • Swap full fat for reduced, low or no fat dairy foods. 
  • Select lean meats and poultry.   
  • Remove skin from chicken and turkey.
  • Cook with polyunsaturated or monounsaturated oils, such as canola, sunflower, soybean, olive, sesame and peanut oils. 
  • Limit the amount of fast foods and take-away meals you eat including deep-fried and baked foods including store bought biscuits, pastries and pies.

Nuts

Nuts are one of the best sources of Omega 3 fatty acid which have been shown to be the most powerful modifier of AMD.  A small handful (particularly almonds, walnuts and Brazil nuts) two or three times per week is recommended.

Exercise

Studies indicate that the equivalent of a 50 minute brisk walk, three times a week as a minimum, is beneficial.

Minimise light exposure

Wear sunglasses and a hat to protect your eyes from light induced damage.

No smoking

Smoking greatly increases the risk of blindness from wet AMD and many other eye diseases by 300%.

Remember to regularly check the vision in each eye independently, particularly while reading. The Amsler grid chart is also very useful, though most people find that blurring or distortion of their reading vision is the first sign.

You must report any changes (blurring, distortion of central shadow) to your ophthalmologist promptly. Early intervention is critical to prevent irreversible visual damage.

You will undergo standard preliminary examination by an orthoptist, including distance and reading visual acuity, intraocular pressure and OCT imaging. Your eyes be dilated with drops to enable a detailed examination of the retina.

If there is evidence of neovascular or “wet” AMD, prompt treatment with anti-VEGF drugs is essential and usually is performed on the day, to prevent further or irreversible visual deterioration. Regular reviews, initially four weekly, will then be arranged.

A class of drugs called anti-VEGF agents have revolutionised the management of neovascular or “wet” AMD. These drugs block the effect of an agent called Vascular Endothelial Growth Factor. This is a fertiliser produced by the body to grow new blood vessels. While this is an essential process while a baby is growing or if there is a wound that needs healing, some diseases trigger VEGF production as part of the disease process causing swelling, bleeding and scar tissue formation. In macular degeneration, an unknown trigger causes new blood vessels to grow under the retina, which pushes the retina upwards, causing distortion and blurred vision. Injections into the eye cavity of an anti-VEGF drug, such as Avastin, Lucentis or Eylea, inactivate VEGF and suppress the neovascular complications. These injections are performed on a regular basis from 4 weeks through 3 monthly intervals, depending on the disease activity. The injections are performed in the clinic with antiseptic and local anaesthetic drops. The injections are safe and virtually pain-free. The risk of an infection entering the eye is now 1 in 20,000 (recent review of results at Bascom Palmer Eye Centre) and rarely cause cataract formation.

Fortunately, Australia has an outstanding public health awareness strategy for wet AMD, largely due to the efforts of the Macula Disease Foundation (MDFA), encouraging early referrals and prompt treatment, compared with most other countries. Further, anti-VEGF drugs, such as Lucentis and Eylea, are supported by the government via the pharmaceutical benefits scheme (PBS) to minimise out of pocked expenses for the patient.