Eye health matters. We all know that our eyes are very sensitive organs that need protection. We also all know people with poor eyesight.
In our modern world our eyes are constantly being bombarded by damaging forces such as powerful UV rays from the sun, free radicals which constantly erode the macula, and toxins from the environment (like car exhaust, pollution, chlorine, dust, etc.) that cause dryness, eye strain and inflammation.
Even if we are not afflicted with serious eye problems there are often nagging difficulties that we would prefer not to have to deal with, such as poor night vision, problems with glare, poor discernment of colour and contrast, and dependence on glasses or contact lenses.
In fact, we are so accustomed to this situation that we assume that deteriorating eyesight is an unavoidable part of the ageing process.
But is it?
We also know people who, despite advanced years, still have healthy eyes.
What is the difference between people who suffer from such problems as cataracts, macular degeneration and glaucoma and those who do not?
And can we do anything to increase our chances of falling into the group that does not have to deal with the associated problems?
Let’s consider some of the common eye health problems in a bit more detail.
A cataract is a cloudy area in the lens of the eye, causing blurred or fuzzy vision and also sensitivity to glare. Driving at night becomes difficult mostly because of sensitivity to the glare of headlights.
Developing cataracts is associated with getting older (although it is possible in younger people and even children). Also, women have a slightly higher risk of developing the condition than men.
Some other risk factors include a genetic predisposition, diabetes, glaucoma (where the treatments increase the risk), and long-term use of steroid-containing medicines such as for asthma and emphysema.
Finally, certain lifestyle choices are risk factors: smoking and heavy alcohol use and too much unprotected exposure to UV light.
Age-related macular degeneration (AMD)
Age-related macular degeneration occurs when the macula, an area at the back of the retina, begins to break down.
Fragile, leaky blood vessels start to develop in the centre of the retina (the macula) which is the region that is most sensitive to detail.
People suffering form the ailment lose central vision while maintaining peripheral vision. This means that total blindness usually does not occur, but effective vision is destroyed – one can see that a person is present but cannot identify the features, or know that there is a clock on the wall, but cannot read the time.
Since AMD affects the region of the eye responsible for many of the things that make life worthwhile – including reading, writing, recognising people and driving the car – this disease impacts very severely on one’s quality of life.
Two forms of macular degeneration are identified:
* The dry form is associated with general aging – drying and thinning of the macula tissue takes place slowly, and loss of vision is also a slow process.
Central vision becomes blurry (and straight lines might look wavy) before disappearing altogether.
* The wet form occurs when abnormal blood vessels develop beneath the retina, and leaking fluid and blood destroys the macula.
This is the more common type of disease being responsible for about 90 % of all vision loss due to macular degeneration.
Of all the eye diseases, AMD in particular is on the rise, and, according to the WHO, has reached epidemic proportions.
So is there something to be done to prevent it, stop it in its tracks if it has begun, and maybe even turn it around, without having to resort to drugs?
Glaucoma creeps up on us without warning – it has been estimated that about half of the people suffering from this disease are not even aware of it!
However, it leads to loss of vision as time passes, and needs to be prevented or, at least, its progress needs to be halted.
The main outcome of this disease is damage to the optic nerve. This nerve carries images from the eye to the brain, so you can understand how important it is that it functions properly.
One of the contributing factors is raised pressure within the eye (called intraocular pressure) but other factors also play a role: diabetes, high blood pressure, severe nearsightedness and the thickness of the central part of the cornea.
Certain groups of people are also at higher risk than others. These include the following:
* People over the age of 60 are 6 times more likely to get this disease than younger people.
* Some forms of glaucoma are hereditary – if you have a family member with the disease your chances of developing it increase.
* Certain forms of eye injury can lead to the development of glaucoma. Bruising or penetrating of the eye can have this effect probably because the drainage system of the eye gets damaged. People who play baseball and boxers are susceptible to this kind of injury.
There is gathering evidence that one can safeguard the health of one’s eyes by ensuring adequate supplies of certain nutrients, and reducing the intake of undesirable foods, particularly processed foods.
What does the research on eye health show?
Predictably, one’s lifestyle choices have a major role to play in the deterioration of the eyes, and there are definitely things that one can do to reduce the risk of conditions such as macular degeneration and cataracts.
And, interestingly, the AMD epidemic is restricted to industrialised countries where processed foods have become the norm. Is there perhaps a connection to be made here?
Here is a brief discussion of some of the nutrients that play a role in eye health.
Omega-3 essential oils
Eating fish is good for your eyes.
Australian researchers into eye health have reported on the results of 9 studies which have found that people who regularly eat oily fish twice a week have a reduced incidence of AMD and severity of the disease. Huge numbers of individuals were involved – 89,000 subjects including 3,200 individuals suffering from AMD.
In 2003 researchers from Harvard Medical School published the results of a study of people with AMD and how their diets affected their condition. It was clearly shown that high-fat diets increase the risk of developing the disease – up to three-fold when compared to people on lower fat diets.
While animal fat was found to double the risk, a more startling finding was that vegetable fat intake also had an effect on the rate of development of AMD.
High levels of these fats, generally considered to be ‘good fats’, increased the risk of getting AMD by nearly four-fold. And the more eaten, the greater the risk.
Increased risk was also directly linked to the intake of processed foods, which are usually full of the undesirable trans fats.
On the other hand, certain fats were shown to have a protective effect, most notably Omega-3.
The National Institutes of Health in the USA sponsored a trial between 1992 and 1998. A sample of 4519 people between the ages of 60 and 80 years were checked for AMD, and how far it had progressed if present. A questionnaire about food choices was also used.
They found that people who ate more fish (at least two servings per week of fatty fish - again!) were least likely to have the disease.
Essential fatty acids are critical for proper visual development in infants. Also, in adults, deficiencies of essential fatty acids, particularly Omega-3, can lead to impaired vision.
Studies suggest that prolonged deficiencies may increase the risk of damage to the retina. Essential fatty acids (EFAs) also play a role in helping aqueous eye fluids to drain, which helps regulate intraocular pressure so may play a role in reducing the incidence of glaucoma.
Omega-3 also plays a role in preventing Dry Eye Syndrome (DES) which is fairly common, particularly in women. Researchers at Brigham and Women's Hospital in Boston (a teaching affiliate of Harvard Medical School), have shown that high levels of Omega-3 fatty acids reduce the incidence of DES by 20 %.
In addition, the ratio of Omega-3 to Omega-6 is important: when it reached 1:15 a 2.5-fold increase in DES was observed.
Maintaining a better balance of these Omega fats is vitally important for many different physical ailments, many of them associated with inflammatory conditions. Women who consumed 5 servings of fatty fish (tuna in this case) per week had a 68% reduced risk of developing DES.
For most people, the idea of eating fatty fish regularly is unacceptable: some find it unpalatable, and others find it hard to come by or expensive. In such cases supplementation is the obvious alternative.
Adding fruit and vegetables to one’s diet is a common cry, and the same holds true if you are serious about reducing your risk of developing AMD.
When the dietary records of more than 1,700 older women were followed for 15 years it was found that a regular intake of lutein and zeaxanthin – both carotenoids – reduced the risk of developing AMD by more than 40%.
In addition, the National Eye Institute (USA) reported in 2002 that antioxidant supplementation could reduce predicted vision loss significantly (19%) in women already in the early stages of AMD. This study involved 3,600 older women over 8 years.
Their recommendations were for Vitamin C (500 mg), Vitamin E (400 IU), beta-carotene (15 mg), zinc (80 mg) and copper (2mg).
Since then further studies have shown that beta-carotene is but one member of a large family of carotenoids, and that others such as lutein and zeaxanthin play an even bigger role in eye health – so the complete complex family of carotenoids is almost certainly better than an isolated member such as beta-carotene.
One way in which antioxidants may play a protective role is to reduce inflammation, which strengthens the walls of the blood vessels and therefore protects them against leakage.
The carotenoids that have been studied for their role in eye health are as follows:
* Beta-carotene (which is largely responsible for the wonderful colour of carrots, hence its name) is vital. Grandma also used to say that eating carrots gave you bright eyes – and she was right! This carotenoid is a precursor to Vitamin A, meaning that the body can synthesise its own Vitamin A from beta-carotene. So it plays a role similar to that of Vitamin A discussed below.
* Lutein (found in spinach, kale, Swiss chard, collard greens, mustard greens, corn, and egg yolks) helps to prevent free-radical damage of the outer edges of the macula by filtering out blue-spectrum light.
* Zeaxanthin (from orange and yellow fruit and vegetables) is found in high amounts in the central part of the macula and also plays a protective role.
* Lycopene, from tomatoes, is also very beneficial for eye health.
* Sulphoraphane, from broccoli, protects the retina from oxidative damage.
As time goes by it is very likely that other members of the carotenoid family and the flavonoids will also be found to be essential for healthy eyes – the whole family is far more effective than individual members acting alone.
Vitamins also play an important role in eye health.
* Vitamin A
A deficieny of Vitamin A causes night blindness which, if not corrected, can lead to xerophthalmia, with dryness in the eyes, ulcers on the cornea and swollen eyelids and eventual blindness. The good news is that this can all be prevented by ensuring adequate Vitamin A intake.
In addition, Vitamin A has been reported to prevent cataract formation and may have a role in preventing blindness from macular degeneration.
If you smoke or drink, extra vitamin A is essential because tobacco keeps your body from absorbing it from your diet, and drinking depletes what you already have in your body.
And, by the way, advice to eat carrots regularly also plays a role in keeping up your Vitamin A levels – beta-carotene gets converted into Vitamin A within the body!
* Vitamin B
Raised homocysteine levels are a risk factor for AMD (as well heart disease).
Homocysteine is an amino acid breakdown product that increases the build-up of plaque in the arteries, amongst other things. Vitamin B lowers homocysteine levels, and protects against the development of AMD or the progression of the disease once it has begun.
In particular, in a Harvard study of over 5000 women for over 7 years, vitamins B6, B12 and folic acid (also a member of the Vitamin B family) were administered with positive results. Incidentally, the researchers were sure that the same beneficial effects would be experienced by men!
* Vitamin D
Low levels of Vitamin D are an indicator of risk of eye disease. Raised levels of the vitamin result in reduced levels of inflammation as well as reduction if growth of blood vessels in the retina – both of which conditions lead to damage of the eye.
Studies on large populations of people have shown that those with the highest levels of Vitamin D in their blood lower their risk of getting AMD by up to 40%.
The recommended intake of vitamin D for eye health is around 1000 IU daily.
* Vitamin E
Vitamin E also occurs naturally in high quantities in the eye, so depletion of this vitamin is almost certain to cause problems.
Tocopherols, which are members of the Vitamin E family, are potent eye protectors, probably because they are powerful free radical destroyers.
In an extensive study involving nearly 5,000 people, researchers found a 25 percent lower risk of developing advanced stages of AMD when a nutritional formula including vitamin E was taken.
Many eye doctors recommend that their patients supplement their diet with a daily multivitamin that contains up to 400 International Units (IU) of vitamin E in combination with other antioxidants as part of their preventative eye care.
* Vitamin C
Vitamin C levels are naturally high in the eye. One mechanism whereby aspirin increases the incidence of eye disease might be because it increases the need for dietary Vitamin C.
High levels of Vitamin C reduce the risk of cataract formation as well as age-related macular degeneration and glaucoma!
So how much vitamin C should you be getting? The U.S. RDA is 60 milligrams (mg) for both males and females. You absolutely must get the RDA every day – it is the absolute minimum.
In fact, much higher quantities are frequently recommended, going up to 1000 mg per day or more. Not only are humans unable to synthesise their own vitamin C (unlike most other species), but we also can't store it in our bodies for very long.
If you smoke, drink or have diabetes, you should try to take in extra vitamin C, because your levels will tend to be lower than average.Other nutrients for eye health
* Zinc and copper
Zinc helps your body absorb vitamin A and is also part of an enzyme in your body that reduces the number of free radicals. Zinc has been shown to protect against macular degeneration and night blindness and assist with focussing and reading fine print. You can get dietary zinc from oysters, hamburgers, wheat, and nuts.
* Carbohydrate intake
Researchers at Tuft’s University (USA) found that people eating starchy carbohydrates are 40 % more likely to develop AMD than those with lower intakes of those foodstuffs.
High glycemic edge carbohydrates are the most dangerous, probably because they cause spiking of the insulin response. All this ties in with the general recommendation that we need to reduce our intake of refined carbohydrates, sugars and processed foods.
* Stop smoking!!
Smoking increases the risk of eye disease, interestingly, especially in women.
* Lose weight.
As if people dealing with weight issues do not already have enough to cope with, there are also findings that suggest that this condition is a problem for maintaining eye health.
The evidence suggests that overweight people, women in particular, are less able to metabolise lutein and zeaxanthin properly. These are important antioxidants for maintaining healthy eyes.
Some commonly used drugs are implicated in deterioration of eye health. Aspirin, for example, has been shown to accelerate AMD, and increase the incidence of retinal haemorrhage.
As long ago as 1988 a DR JD Kingham noted that people presenting with decreased central vision and macular haemorrhaging had recently been using aspirin and other drugs intended to reduce blood clotting by interfering with the platelets.
In addition, certain anti-inflammatory drugs (NSAIDs) have also been shown to increase the incidence of cataract and subsequently AMD. And there are others – too numerous to mention here.
The negative side effects of medicinal drugs are wide-reaching, and being able to stay off such medication for as long as possible is very advantageous. Paying attention to one’s nutrition can make this possible, and is well worth the effort.
As with many aspects of our health, eye health depends largely on our lifestyle choices and the quality of the nutrition that we are getting. For the basics of nutrition that can help with eye health, go to our page on Nutrition, Food and Supplements.