Eye problems are the most feared medical diagnosis. Macular degeneration, a process that obstructs vision by initially damaging fragile capillaries in the eye, is the leading cause of blindness among Americans over age 50. Approximately 25 million adults currently suffer from age-related macular degeneration [AMD]; up to 37 per cent of people over the age of 75 have some form of AMD, and by the age of 80, 25 per cent of all Americans, for instance, will have lost eyesight due to this disease.
One type of AMD occurs when the tiny vessels in the back of the eye are weakened, allowing blood to seep out and leaving the eye defenceless to damage from the sun’s powerful rays. This can cause a dark spot that blocks — or, blurry lines that distort — anything in your field of vision. Legal blindness from AMD can sometimes take its toll in mere weeks.
Types
There are two types of age-related macular degeneration [AMD]: dry and wet. Dry AMD is the less severe of the two and accounts for 90 per cent of all cases. In dry AMD, yellowish spots called drusen begin to accumulate below the macula, breaking down its light-sensing cells and causing distorted vision. If dry AMD advances far enough, it can become wet AMD, so named because it arises when tiny, abnormal vessels begin to grow behind the retina towards the macula. These vessels can leak blood and fluid that damage the macula, not to mention the scar tissue from burst vessels, or vision blockage from new vessels that may occur. Seeping fluid leads to rapid and severe vision loss. Wet AMD almost always takes place in people who have already suffered dry AMD, usually resulting in legal blindness. Legal blindness is defined as visual acuity less than 20/200, or visual field restriction to 20 per cent, or less.
Other Issues
AMD isn’t the only threat to aging eyes. Glaucoma, which is the most common cause of blindness in all age groups, affects the optic nerve and usually remains undetected until a significant amount of vision has been lost. Cataracts, too, are quite common, afflicting two-thirds of individuals over age 70 with the inability to focus. Although vision problems are pervasive in the elderly, over one-third of the 20 million+ diabetic Americans also suffer from some form of eye disease.
Unfortunately, even in this age of medical progress, there are no cures for eye disease and resulting blindness. Cataract operations and laser surgery, for example, benefit a certain percentage of patients, and although they can delay vision loss, they cannot prevent it. Indeed, there was little hope for aging eyes — until now. Luckily, we now know that risk of eye disease can be reduced by controlling one simple factor in our lives: nutrition.
New medical research indicates that specific antioxidants can lower the risk of eye disease and prevent macular degeneration, cataracts, and glaucoma from occurring. These antioxidants include vitamin E, vitamin C, and an amino acid called taurine. But, the most important defenders of the eye are a class of compounds called the carotenoids, which include beta-carotene and, most notably, a versatile and potent nutrient known as lutein.
Lutein, Carotenoids & Zeaxanthin
Lutein appears to prevent the risk of macular degeneration and other eye illnesses by protecting the fragile back of the eye from harmful blue light.
Carotenoids are a group of antioxidants found in concentrated quantities in fruits and vegetables. There are two major classes of carotenoids: the carotenes, including beta-carotene, and the xanthophiles, which include lutein and a similar compound called zeaxanthin. While beta-carotene, responsible for the yellow and orange of foods, like squash and carrots, is the most famed carotenoid, it is virtually absent in the eye. This is where lutein and zeaxanthin enter the picture.
Age-related macular degeneration occurs when cells break down in the macula, a yellow spot at the centre of the retina that is responsible for our clear, central, or focused vision. This breakdown process slowly and progressively destroys sight in the centre of the field of vision, although it does not affect peripheral vision.
Lutein and zeaxanthin work by accumulating in the macula and screening out harmful blue light that can damage the back of the eye [unlike ultraviolet light, which can also damage the eye, blue light is part of the visible spectrum, known as the short wave]. Although xanthophiles are found primarily in leafy and green vegetables, especially kale, spinach, peas, lettuce, and broccoli, they are actually yellow and orange in colour, a fact hidden behind the chlorophyll that gives these vegetables their rich, dark hue. By pigmenting the macula, lutein and zeaxanthin act like sunglasses, filtering out destructive rays from the daily onslaught of light waves. They also fight free radicals that can threaten to impair our vision.
Research indicates that macular degeneration is probably caused by oxidative damage from free radical activity and poor circulation in the macula. Studies in animals demonstrate that the visible light entering our eyes each day, especially ultraviolet light, can lead to extreme free radical damage. Light, of course, is essential to the health of the eye. Without it, not only would we see nothing, but our retinas would shrink. Light also stimulates the production of certain hormones [although its absence does the same to other hormones; melatonin, a sleep hormone, is secreted only when we’re in the dark]. Unfortunately, the ultraviolet component of all visible light coming from the sun can also hurt us with free radical damage, producing cataracts, macular degeneration, and even cancer with its free radicals. The fatty outer layer of the macula is particularly vulnerable to oxidative damage from the sun, which is why this area is the most common locus of degeneration. Although the retina and the macula are packed with carotenoids, especially lutein and zeaxanthin, to fend off harmful free radicals, the outer edge of the macula is less protected by these antioxidants than the rest of the eye. In sum, the more we shield our eyes from excess sunlight and the more we boost our intake of sight-saving carotenoids like lutein and zeaxanthin, the better we’ll be able to preserve the macula — and our vision — for a lifetime.
Study
A groundbreaking study in Journal of the American Medical Association analysed the dietary patterns of 356 cases/subjects aged 55-80 who had been diagnosed with advanced AMD during the year prior to enrolment in the study. They concluded that those with the highest dietary intake of carotenoids had a 43 per cent lower risk for AMD compared with those who had the lowest intake. Lutein and zeaxanthin, which are primarily obtained from dark green, leafy vegetables, were most strongly associated with a reduced risk for AMD. In particular, a higher frequency of intake of spinach, or collard greens, was associated with a substantially lower risk for AMD.
A one-year study reported in Experimental Eye Research showed that after just 20-40 days of taking 30mg of lutein per day, the macular pigment optical density in the subjects’ eyes began to increase uniformly, providing a 30-40 per cent reduction in the blue light reaching the photoreceptors, Bruch’s membrane, and the retinal pigment epithelium — the vulnerable tissues affected by AMD.
It may seem too simple that eye diseases with no known scientific cure could be prevented so easily, but it turns out mom was right: we should eat our vegetables. Research suggests that eating leafy greens packed with lutein and zeaxanthin can ensure clear sight for most of us as long as we live.
Risks For AMD
- The main risk factor for AMD. In the United States, an estimated 18 per cent of people between the ages of 55 and 64 have this disease, increasing as we get older
- Because the fragile cells of the macula are extremely vulnerable to free radical damage, it is important to stay away from saturated fats and cholesterol, which are particularly instrumental in facilitating free radical reactions. Alcohol can deprive the body of protective antioxidants. By consuming a varied diet of fruits and vegetables, one can ensure that their eyes have the antioxidants they need to counteract the threat of free radical damage. This is also especially important for children, since their eyes are still developing and depend on these protective nutrients
- The very light that allows us to see can also take that ability away. The ultraviolet component of light is especially harmful to the macula, causing excessive free radical damage. Wearing sunglasses, or taking care to shield the eyes from constant sunlight will reduce the deterioration of the macula
- Smoking reduces the amount of free radical-fighting antioxidants in the eye, more than doubling the risk of AMD
- Several studies show that AMD may be inherited. If AMD is part of a patient’s family medical history, it might be in one’s best interests to focus on preventing it in their own eyes
- Women over 75 have twice the risk of developing AMD as men the same age
- Eye colour. Individuals with light-coloured eyes [blue, or green, for example] have a much higher risk for AMD than those with darker eyes
- Heart disease and diabetes. Good eyesight depends on proper blood flow through the eyes. High blood pressure, or other forms of heart disease, as well as diabetes, can increase a person’s likelihood of getting AMD, because these conditions may result in poor circulation to the eyes, as well as other parts of the body.
By taking a full complement of supplements, including vitamins C, E, and A, selenium, zinc, taurine, and antioxidants, like lutein and zeaxanthin, as well as eating a healthful diet filled with leafy greens and juicy fruits, a person can keep their eyes alert and strong throughout life.
Recommended Dosage
For General Health
Carotenoids
Through leafy green vegetables, or 5-10mg a day
Special Conditions
Lutein
AMD: 20mg a day
Cataracts/glaucoma: 5-20mg a day.
