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Condition - Understanding Age-related Macular Degeneration

By Nutri People

The human eye is actually very much like a camera, with the retina (the layer of tissue at the back of the inner eye) being like the film in the camera. The macula is the part of the retina that makes our vision sharper and is responsible for what we see straight-ahead of us (called our central vision). We use this central vision for reading, writing, driving, watching television, recognising faces and carrying out close, detailed work. Macular degeneration is the gradual deterioration of the macula, which destroys the central vision, leaving just the peripheral (side) vision, which can make performing the many everyday tasks that the rest of us take for granted very difficult – even walking up and down the stairs can be a problem.

Macular degeneration is rare in young people, but commonly affects people over the age of 50 – hence the name ‘age-related macular degeneration’, often abbreviated to AMD. It’s estimated that 500,000 people in the UK suffer from AMD,and one in fifty people over the age of 65 are blind in one or both eyes due to this condition.  There are two types of AMD, referred to as ‘dry AMD’ and ‘wet AMD’. 

What is dry AMD?

About 90% of cases of AMD are dry AMD, which develops gradually over time and generally affects both eyes, although vision can be lost in one eye while the other eye seems unaffected. With dry AMD, small fatty deposits form under the macula, which can cause progressive degeneration of the light-sensitive cells in the macula, leading to a gradual blurring of central vision in the affected eye. As the condition worsens, you may see a blurred spot in the centre of your vision. It is possible for the dry form to suddenly turn into wet AMD.

What is wet AMD?

The wet AMD is a less common but a more aggressive and rapid form of the disease. It is caused by the growth of abnormal and very fragile blood vessels under the macula. These new vessels can leak blood and fluid (hence ‘wet’ macular degeneration), which damage the macula. Although only 10% of people with macular degeneration have wet AMD, it causes most of the vision loss associated with macular degeneration. An early symptom to look out for with wet AMD is a central blind spot or visual distortion – where straight lines appear wavy or crooked. 

A number of contributing factors have been identified:

  • Age – this is the main risk factor and increases with advancing years.
  • Caucasian Race – macular degeneration is more common in caucasians than it is in other groups of people, especially after age 75.
  • Gender – women are more likely to develop macular degeneration than men.
  • Light-Coloured Eyes – people with blue or light-coloured eyes may be at greater risk of developing the condition than those with darker eyes.
  • Family History of Macular Degeneration – if someone in your family has had macular degeneration, your risk of developing it is increased.

Such factors cannot be altered, but others are modifiable:

  • Sun Exposure – some experts believe that long-term exposure to ultraviolet light may damage the cells of the macula and increase your risk of developing macular degeneration, but this risk is still unproven and remains controversial.
  • Obesity – this increases the risk of AMD and may be related to an increase in free-radical damage and increased inflammation. 
  • Atherosclerosis of Retinal Vessels – the build-up of fatty deposits in the blood vessels that supply the retina (called atherosclerosis) can impair blood supply carrying vital nutrients to the eye.
  • Cigarette Smoking – some studies have shown that smokers are at an increased risk of developing AMD, and even non-smokers who are exposed to passive smoking.
  • Cardiovascular Disease– the risk factors for cardiovascular disease (including high blood pressure, elevated cholesterol levels, diabetes, smoking, high intakes of saturated fats and alcohol) have been associated with AMD in some studies.
  • Free Radicals – these are chemical substances produced in the cells when we obtain energy by combining the food we eat with the oxygen from the air we breathe. Free radicals are capable of reacting and damaging many of the cells’ components. Long-term cumulative damage by free radicals has been suggested to be an important factor in the development of AMD.
  • Nutrition– some studies have associated a low intake of fruits and vegetables, in particular, dark green leafy vegetables (which are a good source of important antioxidants including lutein and zeaxanthin), and a high fat intake with a greater risk of developing AMD.

Nutrients for supporting eye health:

 

  • Antioxidants – free radicals have been implicated in the development and progression of AMD. Antioxidants can help to mop up these free radicals. Some antioxidant nutrients have innate antioxidant activity including vitamins A, C, and E. Other nutrients function as important cofactors or “helpers” for antioxidant enzymes, including the minerals zincand selenium.
  • Carotenoids – these are naturally occurring pigments found in certain plants with potent antioxidant properties. They are also responsible for the orange, red or yellow colouration of many fruits and vegetables. Lutein and zeaxanthin are two carotenoids found in the macula, where scientists think they may help to protect it against light-induced free-radical damage. Astaxanthin is a pink carotenoid derived from algae with powerful antioxidant properties and may help to support eye health. Lycopene is a red pigment present at high levels in tomatoes. A study reported in the Archives of Ophthalmology showed that persons who had the lowest blood levels of lycopene were twice as likely to have AMD when compared to those with the highest levels.
  • Zinc is found in high concentrations in the part of the retina affected by AMD, and retinal zinc levels have been shown to decrease with age.
  • Bilberry is high in antioxidant substances called flavonoids that may help to maintain eye health.
  • Fish Oil – a study by scientists at Tufts University in Boston showed that a diet rich in omega 3 fatty acids (including EPAand DHA) may reduce the risk of AMD. Fish oil is a good source of omega 3 fatty acids.

 

Dietary recommendations

  • Eat a variety of brightly coloured fruits and vegetables that are rich in antioxidants. Studies suggest that diets with plentiful supplies of antioxidant-rich fruits and vegetables are associated with a reduced risk of AMD. Consume foods rich in the carotenoids lutein and zeaxanthin including dark green leafy vegetables (spinach, kale, collard greens, turnip greens, mustard greens, dandelion greens, romaine lettuce and watercress), broccoli, courgette, garden peas, Brussels sprouts and sweet yellow corn. Some fruits are also good sources of carotenoids including apricot, mango, cantaloupe, guava, watermelon, peach, and gojiberry.
  • Tomatoes are a good source of lycopene. Cooking tomatoes makes lycopene more available for the body to use.
  • Grapes (red and purple), and red, blueand purple berries (bilberries, elderberries, cranberries, blackcurrants and blueberries), are a rich source of flavonoids called anthocyanins, which have been shown to enhance production of rhodopsin, a protein/pigment found in the light-sensitive cells in the retina of the eye that allows for night-vision. Anthocyanins may also help to support circulation within the capillaries of the retina.
  • Eat low-glycaemic-index foods, which simply means eating foods that release their sugar more slowly into your blood stream. Some research suggests that this may be of benefit to those with AMD. This means replacing foods such as sugar, chocolates, cakes, biscuits, pastries, white bread made with refined white flour, white rice and pasta, sweets, starchy vegetables, sugary drinks and fruit juice, with nutrient-dense unprocessed foods including whole grains, fruits, legumes (beans, peas and lentils), nuts and seeds and non-starchy vegetables.
  • Eat foods rich in omega 3 fatty acids, including oily fish (salmon, sardines, fresh tuna, mackerel and herring) and cold pressed oils (flax, hemp and walnut oil). 
  • Reduce your intake of vegetable oils rich in linoleic acid, including safflower, sunflower, corn and soya bean oil.
  • Green tea is a good source of flavonoids called ‘catechins’. Recently, scientists have shown that green tea catechins penetrate into the tissues of the eye, including the retina, where they may protect the eye against damage by free radicals.
  • Drink plenty of bottled or filtered water, especially in hot weather.
  • Reduce consumption of alcoholic drinks.
  • Reduce foods that are high in saturated fats, such as red meat, dairy products and fried foods. High-saturated-fat diets can cause plaque build-up along blood vessel walls, including the macular vessels, which impedes blood flow. Choose lean cuts of meat and low fat cheeses.
  • When preparing foods, grill, bake or stir fry with olive oil.

 

Lifestyle changes that may be helpful:

  • Don’t smoke and avoid exposure to second-hand smoke. Smoking produces free radicals and can reduce the blood supply by narrowing and damaging blood vessels, and thickening the blood (by increasing the production of red blood cells).
  • Protect your eyes by wearing brimmed hats and sunglasses that contain UV protection.
  • Give your eyes enough rest. Avoid straining with dim light. Use full spectrum light bulbs for light during the day and evening.
  • Exercise. This helps to improve the circulation of oxygenated blood throughout the body, including the eyes.  

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