Woodland Herbs
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Eye Health

Diagram of eyeOur eyes are exceptionally powerful information gatherers.  To begin to understand what these remarkable structures do, a favourite comparison in biology textbooks is that between the eye and a traditional camera.  Though this analogy has its limits (eg instead of one image from a camera, the brain receives an image from each eye and combines them) it's suitable for starting to get a handle on such a complex organ.

Like that of a camera, the lens of the eye enables the eye to focus on different things at varying distances. The coloured iris regulates the size of the black pupil similar to a camera's aperture setting. Often compared with a strip of camera film, the eye's retina is a layered, light-sensitive membrane which receives visual information through the stimulation of photoreceptor cells called rods and cones. In the centre of the retina is the macula, an area which receives vision from the central visual field and has the ability to see colours.

In someone with good vision, the lens focuses light waves on the retina, making objects appear sharp and clear. Problems with focusing the light waves leads to problems that are often resolved by wearing spectacles or contact lenses.

The retina is covered in over 130 million photoreceptors, made up of around 125 million rods and 7 million cones.  Rods are very sensitive to light, but not to colour. They're responsible for vision in the periphery, and vision in low lighting conditions, such as night-time. Cones are colour sensitive and there are three types: red, blue and green. Each type is responsive to the respective region of the visual spectrum. When all three cone photoreceptors are activated by light, white is perceived, an absence of all three cones being activated produces the perception of black.

The light waves are then converted into nerve impulses which travel along the optic nerves to the visual cortex, a large system at the rear of the brain where the perception of vision is created. Humans only  'see' objects which emit or are illuminated by light waves in our receptive range, which is said to be only about 1/70 of the entire electromagnetic spectrum.  Other animals such as insects are sensitive to shorter (eg ultraviolet) or longer (eg infrared) wavelengths.

Cells in the body constantly use oxygen as energy, resulting in highly reactive, damaging, molecules known as free radicals.  Constant stimulation of the photoreceptors means that during vision the retina uses more oxygen than any other tissue in the body, and the retina can suffer from free radical damage (also known as oxidative damage). This is the cause of many degenerative eye conditions. The lens is also susceptible to oxidative damage, leading to cataract formation, because its protective cells don’t regenerate themselves. Antioxidants help to prevent this oxidative damage.

Unsurprisingly for such complex organs, our eyes are associated with many conditions, some of which are:
Myopia (near sightedness). When light rays come to a focus before they reach the retina, making distant objects appear blurred.  This may be caused by an elongated eyeball or a thickened lens.
Hypermetropia (far sightedness). When light rays are focused beyond the retina, making near objects appear blurred. This may be caused by a shortened eyeball or a thinned lens.
Astigmatism. Occurs when the curvature of the lens is not uniform, making the image formed on the retina unfocused.
Night blindness. Can result from a deficiency of vitamin A, which is essential to to the synthesis of retinal, an essential compound involved in animal vision.
Glaucoma. Occurs when the aqueous humour (the gelatinous fluid between he cornea and the lens) does not drain properly, increasing the pressure in the eye.
Stye.  Infection of a sebaceous gland of the eyelid.
Conjunctivitis. An inflammation of the conjunctiva, the mucous membrane that lines the inner eyelid.
Macular degeneration. Deterioration of the part of the retina known as the macula in which the centre of the visual field becomes blurry or blank.
Cataracts.  A clouding of the lens, caused by proteins breaking down. Two leading causes of cataracts are similar to that of macular degeneration: exposure to UV light and damage from free radicals.
Blepharitis.  Eyelids are sore and inflamed, often caused by infection, asthma and allergies.

9 tips for healthier eyes
1. Stop smoking.  Tobacco smoke contains numerous toxins and free radicals harmful to eyes, and smokers are up to three times more likely to develop cataracts than non smokers.
2. Protect your eyes from UV damage with sunglasses and brimmed hats.
3. Eat the rainbow.  Antioxidants prevent free radical damage. Studies show that those with a high intake of antioxidant rich fruit and vegetables have a lower risk of cataracts and macular degeneration.  Dark green vegetables such as kale and spinach, red peppers, leeks, avocados, peaches and blueberries contain lutein (more on which later) and zeaxanthin, which help project the eyes from UV damage.
4. Take screen breaks.  We blink less when focusing on screens, making our eyes less lubricated. Adjust the brightness, contrast and font size to levels most comfortable to you.  Try a relaxing technique called palming, suggested by William H Bates in his famous 1920 book 'Perfect Sight Without Glasses'.  Simply rest your elbows on your desk, cover your eyes with cupped palms and focus on breathing deeply for a few minutes.
5. Make a date to get your eyes tested.  Adults should have an examination at least once every two years.  Contacts lens wearers should attend regular after-care checks. In Scotland, everyone is entitled to a free eye test and many in England and Wales are entitled to a free test - check with your optician to see if you're eligible.
6. Consider supplementing your diet with eye-friendly nutrients such as Solgar's Advanced Antioxidant Formula, which also contains taurine,  the most abundant amino acid in the retina.  Vegetarians and vegans are often found to be low in taurine, which is present in meat, fish and poultry.  However, beans and nuts contain cysteine and methionine, which can be converted into taurine in the body.
7. Omega 3 fatty acids are particularly nourishing to optical cell membranes, so eat plenty of oily fish or add (uncooked) flax oil to your soups, salads and vegetables.
8. Be protected. Wear protective eye wear when doing DIY and maintenance jobs, and especially if you play racket sports such as squash, a major cause of eye injuries.
9. Consider a herbal helper such as the antioxidant rich Bilberry or Ginkgo Biloba, already a popular choice for those seeking to address circulatory problems, or grape seed extract , a multi application substance often suggested in cases of cataracts and macular degeneration.

Supplement of the Month: Lutein

LuteinLutein is one of over 600 naturally occurring carotenoids. Apart from the gardeners' foe the aphid, animals cannot make carotenoids but  require them for various important functions.   Therefore we must get them through our diet.

Carotenoids are either xanthophylls (which contain oxygen) and carotenes (which contain no oxygen), and usually their purpose is to protect plants from light damage.  They act as nature's own sunscreen. Both lutein and zeaxanthin are xanthophylls found within the retina of the eye and it is thought that they help protect the eyes from oxidative stress and light damage.

Many studies have pointed to a relationship between low blood plasma concentrations of lutein and zeaxanthin, and an increased risk of developing macular degeneration and in 2007 the US's National Eye Institute in Maryland affirmed that these carotenoids protect against vision loss. Also in 1999 a 12 year study into the diets of health professionals found that those with more lutein and zeaxanthin in their diets tended towards having a lower risk of cataracts. In addition to benefiting eye health, a study published in the Lancet in 2001 found that lutein appears to protect against plaque build up in the arteries.

Rich food sources of zeaxanthin include orange peppers, sweetcorn, mangoes and peaches and lutein is found in dark green leafy vegetables such as spinach and kale, broccoli, asparagus and peas. Egg yolks are rich in both zeaxanthin and lutein and in 2009 the University of Massachusetts found that the macular health of older adults with a condition called low macular pigment optical density improved after 5 weeks of eating egg yolks every day.

If you would like to take a supplement, Solgar's Lutein Carotenoid Complex  contains both lutein and zeaxanthin.

Herb of the Month: Bilberry

bilberryBilberries (Vaccinium myrtillus) have been used for centuries, both medicinally and for food.  In the South West England of Thomas Hardy's 1878 novel 'The Return Of The Native', bilberries were known as 'blackhearts' and in Ireland they're called 'fraughan' and are traditionally gathered on Fraughan Sunday, the last Sunday in July. In Scotland they are called 'blaeberries'.

Bilberry fruit contains chemicals known as anthocyanosides, plant pigments with powerful antioxidant properties. Antioxidants help protect cells by neutralising free radicals, and bilberry anthocyanosides may even support the activities of other antioxidants such as vitamin C.  As free radical damage is implicated in numerous eye conditions, including cataracts and macular degeneration, bilberries may be a good choice for those with eye concerns.

Indeed, during World War II, British fighter pilots reported improved night-time vision after eating bilberry jam, and 48 out of 50 participants in an Italian study in 1989 had the progression of their cataracts halted after a four month course of bilberry and vitamin E.  In addition, some studies suggest that these compounds help protect collagen, the protein that makes up 80% of the eye's structures.

A Swedish study published in 2009 suggested that the specific mixture of flavonoids in bilberries may be of significance in the prevention and treatment of cardiovascular problems, and several animal studies have found that anthocyanosides may strengthen blood vessels, improve circulation, and prevent the oxidation of LDL ("bad") cholesterol.

Like many green plants, bilberry leaves contain myrtillin, a substance which is being investigated scientifically for its blood sugar reducing qualities. Further research is required.

If you are pregnant, breastfeeding, are on any medication or have a medical condition, always consult a healthcare practitioner before taking any dietary supplement or herbal remedy.

Offer of the Month: 20% off hayfever remedies

Our special offer this month is 20% off hayfever remedies. Available online or visit this page for more info about hayfever remedies.

Cautions and Contraindications: This newsletter does not substitute the advice of a healthcare professional. We recommend you consult your GP or Medical Herbalist before self-treating with herbs and/or supplements.