It is estimated that everyone will experience vision impairment or an eye condition at some point in their life. We explore natural medicine for eye health.
Understanding eye health
The eyes are our portal to the visual world, with vision being considered the most dominant of the human senses (1). Nowadays, the eyes are overloaded with stimuli from artificial lighting and screens, stimuli unlike those the eyes encounter in the natural world. Aside from the strain this over-exposure to unnatural lighting puts on the eyes themselves, this stimulation is also a lot for the nervous system to process which can lead to stress headaches.
Our eyes are further exposed to pollutants, which can cause irritations to the eyes, and possible inflammations and infections such as blepharitis and conjunctivitis.
It is estimated that everyone will experience vision impairment or an eye condition at some point in their life and require eye care services, and that there is a direct link between eye health, reducing visual impairment, and overall good health and wellbeing (1).
Whilst some eye conditions have genetic factors, many are also contributed to by lifestyle (such as food and exercise), environment (including exposure to pollutants, infectious diseases, and ultraviolet lights), and social and economic factors (including poverty or low income which will impact access to eye healthcare and quality food providing nutrients valuable for supporting eye health).
The leading causes of visual impairments globally are (2):
- Age-related macular degeneration
- Cataract
- Diabetic retinopathy
- Glaucoma
- Uncorrected refractive errors
Factors affecting visual impairment vary depending on the place in the world, but in the UK it tends to be age-related pathologies which affect the eyes the most. There is a worldwide increase in diabetic retinopathy (1), a complication of diabetes affecting the eyes and potentially leading to loss of vision, as well as eye issues associated with hypertension, which is also on the rise.
Herbs and lifestyle factors can provide support that benefits eye health.
How does eye health work?
When considering eye health and the potential for pathologies, there are three main aspects to consider:
- Structural components of the eye itself, and their function in vision.
- The nerve connections between the eye and the central nervous system.
- The blood supply to the eye.
Overview of how the eye works to produce vision
The ability to see clearly relies on a system between the eyes and the nervous system whereby light stimuli activates neuronal impulses with which the brain creates 3D images. This system that provides vision relies on the structural and physiological integrity of the eyes and brain, and the neural connections between them.
The main structural components of the eye that play an important role in this are the cornea and lens at the front of the eye, which focus light onto retinal photoreceptors (1). The iris (the coloured part of the eye) controls the amount of light that reaches the retina by adjusting the size of the pupil. Light reaches the retina at the back of the eye, where the optical images are converted into electrical signals which are transmitted to the brain via the optic nerve, which travels from the back of the eye to the brain.
The white of the eye is also known as the sclera, and at the front of the eye is covered by a membranous layer called the conjunctiva. The macula makes up part of the retina at the back of the eye and is responsible for visual acuity and colour vision. The macula is also called the ‘macula lutea’, lutea meaning yellow, and this yellow pigment is what protects the cells of the macular from the potentially harmful effects of sunlight, and the LED screens of computers and phones. The eyes would have evolved being exposed to bright sunlight during daylight hours, whereas now screens and artificial light are available at any time of day or night.
The blood vessels which supply and drain blood away from the eyes, enter at the back of the eye close to the optic nerve. The main arteries providing blood supply to the eyes are the ophthalmic artery, and the central retinal artery (3).
The health and function of all these structures of the eye are important for eye health.
Understanding the root of healthy vision
There are various biological, environmental, and socioeconomic factors which occur at different stages of life and contribute to the trajectory of individual eye health. Some eye health conditions are determined in part by genetics, some of these tend to occur with age such as cataracts, glaucoma, and macular degeneration, with additional risk factors which may include lifestyle elements such as smoking, alcohol use, and lack of nutrition.
Some eye complaints are linked directly to other health conditions such as retinopathy are caused by diabetes or hypertension. However, at each stage of life there are factors that can impact the likelihood of eye health issues arising.
Before birth genetic determinants, maternal nutrition, intrauterine infection, and maternal smoking can contribute to the picture of eye health, whilst premature birth and low birth weight can be risk factors for eye health issues.
During childhood nutrition, environment, and activity are key components which contribute to eye health. Whilst in adult life the eyes are perhaps overly stimulated, during childhood visual stimulus is actually vital for healthy eye development (such as colour, movement, shapes, faces, etc). Between birth and eight years of age, deprivation of visual stimuli can lead to vision impairment (1).
During childhood and adolescence spending adequate time outdoors in natural lighting is important for eye health. In east Asian cities in the past few decades, there has been an increasingly high prevalence of myopia (short-sightedness) in school children, with up to 20% of school leavers completing secondary education having this eye condition, which is thought to be linked to lifestyle changes meaning that children spend less time outside (4).
Pathologies of the eyes
- Dry eye: Lack of tear film over the cornea and conjunctiva of the eyes. Common in older age, can be due to lack of tear volume, or poor tear quality. Also in rarer cases dry eye is a symptom of other conditions affecting connective tissues such as Sjögren syndrome, rheumatoid arthritis (RA), or systemic lupus erythematosus (SLE or lupus).
- Blepharitis: Inflammation of the eyelids, around 35% of chronic cases of blepharitis are linked to dry eyes.
- Conjunctivitis: Inflammation or infection of the conjunctiva, most common eyes complaint seen in healthcare settings.
- Diabetic retinopathy: Causes damage to the blood vessels supplying the retina and is a major cause of blindness in working-age adults. It can be linked to duration of diabetes, blood glucose levels, and blood pressure. Managing blood sugar levels can help to reduce the risk of diabetic retinopathy (5). It is often asymptomatic until later stages of disease development, and detected at eye examination, therefore eye examinations are particularly important for people with a diabetes diagnosis.
- Hypertensive retinopathy: Damage to the retinal vascular tissue caused by high blood pressure. When hypertension and diabetes are combined there is an increased risk of vision loss.
- Age-related macular degeneration (AMD): Changes in the macular tissue of the retina can lead to visual disturbances and eventually loss of vision. It is the most common cause of permanent, irreversible vision loss in older adults (6).
- Glaucoma: A change in pressure within the eyes, which can lead to compression of the optic nerve, or reduced blood supply. This can lead to irreversible loss of vision, and glaucoma is the second most common cause of blindness worldwide (7), it can occur at any age but is more common past the age of 60 years.
- Cataracts: A degenerative opacity of the lens of the eye and is the leading cause of blindness worldwide. It occurs most commonly with aging, in some cases is congenital, but some risk factors are lifestyle related, such as alcohol use, smoking, exposure to x-ray, undernutrition, and diabetes (8).
Signs and symptoms
Signs and symptoms of eye issues can include:
- Itching
- Irritation
- Foreign body sensation (which continues when there is no obvious foreign body)
- Discharge
- Sensation of dryness
- Photophobia
- Visual disturbances (such as blurring or lights)
- Loss of vision
The following are symptoms more specific to certain conditions.
- Dry eye symptoms: Itching, burning, irritation, photophobia
- Blepharitis symptoms: Itching and burning of eyelid edges, irritation of conjunctiva, photosensitivity, foreign body sensation
- Conjunctivitis symptoms: Discharge, itching or foreign body sensation, photophobia
The following conditions occur either as a complication of another pathology (such as diabetes or hypertension) or tend to occur with age (such as AMD, glaucoma, cataracts). These eye conditions are usually detected at standard eye examinations since they often remain asymptomatic until the later stages.
- Diabetic retinopathy symptoms: Often asymptomatic (eye check important), but can cause gradually worsening vision, blurred or patchy vision, black spot floaters, or flashing lights in field of vision, eye pain or redness, difficulty seeing in the dark and sudden severe, painless loss of vision (5,9)
- Hypertensive retinopathy symptoms: Symptoms usually only appear late in the disease, and it is often diagnosed by eye examination
- AMD symptoms: Dry AMD — painless loss of central vision over years, central blind spots occur later in disease; Wet AMD— rapid vision loss over days or weeks, usually beginning with visual distortion such as blind spots or curving of straight lines (6)
- Glaucoma symptoms: Glaucoma is often asymptomatic but can present with abnormal optic disc detected at eye examination, optic nerve damage, and visual field deficits (7)
- Cataracts symptoms: Initial symptoms can be gradual over many years, including halos or starbursts around lights, needing more light to see well, difficulty distinguishing dark blue from black, and eventually a painless, gradual blurring of the vision (8).
Herbs for healthy eyes
Whilst many eye conditions have a genetic component to them, particularly those which are more common with age such as AMD, glaucoma, and cataracts, there are still many factors to consider which may be beneficial in easing the progression of these conditions, or as a prophylaxis to prevent or delay onset. Herbs for improving the integrity of blood vessels, circulation, and therefore blood vessels of the eyes and retinal blood flow, such as bilberry and ginkgo biloba are particularly helpful and may be considered.
Herbs which can support eye health with infections, inflammations, and irritations include those which have anti-inflammatory properties such as eyebright, plantain, and calendula. Astringent properties are beneficial to tone the tissues when applied topically such as fennel, raspberry leaf, and pomegranate.
Dietary and lifestyle measures to support eye health can be seen in the holistic solutions section.
Eyebright
Eyebright has a long history of affinity with the eyes as suggested by its name, with traditional use being noted as far back as the 14th century where it was said to ‘cure all evils of the eyes.’ Its Latin name Euphrasia was taken from the Greek euphrosyne meaning gladness, and was apparently due to its use in folk medicine for eye complaints (10).
Eyebright acts as an astringent and tonic for mucous membranes when taken internally or applied topically (11), and these properties mean it can help with complaints of the eyes which produce discharge, such as conjunctivitis, or allergic rhinitis / hayfever where the eyes are affected.
Topically a well-strained infusion can make an excellent eye wash also for its astringency and anti-inflammatory properties helping to soothe and reduce secretions from inflamed eyes. It has also been shown to have an anti-microbial effect making it useful in cases of bacterial conjunctivitis.
A study looked at the activity of three types of eyebright extract on human corneal epithelial cells. Of the three extracts used ethanol and ethyl acetate extracts were most useful, whereas heptane extract was not recommended and demonstrated some toxicity whereas the other two extracts did not show toxicity.
The ethanol and ethyl extracts demonstrated beneficial effects in free radical scavenging and reducing their toxicity in the corneal cell cultures. The authors suggested that these types of extract may be beneficial for treating dry eye and allergies affecting the eyes. They also seemed to reduce inflammation, which was perhaps through an immunomodulatory action rather than a direct anti-inflammatory action (12).
This study was carried out in vitro on cultures of human corneal cells so is not directly applicable to use in humans; however, it does identify mechanisms of action which may explain the long history of traditional application of eyebright as a treatment for eye complaints.
Calendula
Calendula is a wonderful wound healing herb and soother of the skin. It can be applied topically as a wash or soak (made from the infusion, well strained, and left to cool) for the eyes. The combination of astringency and anti-inflammatory properties allow marigold to provide relief from inflammations of the eyes such as in blepharitis, conjunctivitis, and other inflammatory or irritable eye conditions where itching or discharge may be present.
Pomegranate
Pomegranate has an astringent action and provides anti-inflammatory actions for mucous membranes, which may explain its traditional Ayurvedic application in cases of conjunctivitis (13).
Bilberry
Bilberry is rich in polyphenols (providing the deep purple pigment), the specific compounds are anthocyanins which provide a potent antioxidant action. This polyphenol content helps to protect against free-radical damage, inflammation, promotes tissue repair, and specifically improves integrity of blood vessels, and circulation. This is particularly helpful in cases of hypertensive or diabetic retinopathy.
There is also suggestion that bilberries are beneficial for overall eye health by promoting the oxygen and blood supply to the eyes and offering relief of eye fatigue from working at computer screens.
Herbalists also recommend bilberry in cases of macular degeneration, eyestrain, and glaucoma (11).
Ginkgo biloba
Ginkgo biloba has been found to be helpful in improving blood flow and tissue oxygenation. It is recommended to improve blood flow to the retina, and in managing cases of glaucoma and age-related macular degeneration (11).
There are some cases of adulteration with ginkgo extracts, and most studies on its use are based on high dosage extracts. If you are thinking of taking ginkgo for management of an ongoing eye condition it is recommended to seek guidance of a herbalist who will be able to ensure the quality and relevant dosage of any ginkgo extracts given. You can see where to find a herbalist on our website.
Holistic solutions
Nutrition
Sufficient nutrition is essential for development of healthy eyes, maintaining eye health, and as a preventative for some eye conditions. Particularly important are foods rich in antioxidants, vitamin C, vitamin E, and vitamin A.
The following are recommended as management for age related macular degeneration (6):
- Zinc oxide 80 mg
- Copper 2 mg
- Vitamin C 500 mg
- Vitamin E 400 IU units
- Lutein 10 mg (or beta-carotene 15 mg or vitamin A 28,000 units for patients who have not smoked)
- Regular consumption of foods high in omega-3 fatty acids.
- Regular consumption of dark green leafy vegetables may slow progression of the condition.
For cases of diabetes managing blood sugar will be helpful in reducing risk of developing complications such as diabetic retinopathy.
Overall eye health practices
- Regular screen breaks (looking into the distance to change focus, gentle blinking to refresh lenses, eye palming to relax eye muscles, and eye movements).
- Yoga eye exercises can help to strengthen eye muscles and reduce eye strain.
- Tratak is a Yoga meditation practice which also benefits the eyes. Gazing at the steady flame of a candle in a darkened room or gazing at a dot such as a bhindi fixed on the wall at eye-level. Gentle gaze without blinking until eyes begin to water, and then close eyes and keep focus on the image of the flame or dot with closed eyes. When finishing the practice palm eyes and gentle blink open and closed before removing hands. This can be a beneficial practice in the evening or before bed, to help to reduce eye strain especially after screen time.
References
- The Lancet Global Health 2021. The Lancet Global Health Commission on Global Eye Health: vision beyond 2020. https://doi.org/10.1016/S2214-109X(20)30488-5. Accessed August 7, 2023.
- WHO. Blindness and Vision Impairment. https://www.who.int/news-room/fact-sheets/detail/blindness-and-visual-impairment. Accessed August 7, 2023.
- MSD Manuel Consumer Version. Muscles, Nerves, and Blood Vessels of the Eye. https://www.msdmanuals.com/home/eye-disorders/biology-of-the-eyes/muscles-nerves-and-blood-vessels-of-the-eyes. Accessed August 10, 2023.
- Morgan IG, Ohno-Matsui K, Saw SM. Ophthalmology 2 Myopia. Lancet. 2012;379:1739–48. https://doi.org/10.1016/S0140-6736(12)60272-4.
- MSD Manuel Professional Version. Diabetic Retinopathy. https://www.msdmanuals.com/professional/eye-disorders/retinal-disorders/diabetic-retinopathy?query=retinopathy. Accessed August 10, 2023.
- MSD Manuel Professional Version. Age-Related Macular Degeneration. https://www.msdmanuals.com/professional/eye-disorders/retinal-disorders/age-related-macular-degeneration-amd-or-armd?query=macular%20degeneration. Accessed August 10, 2023.
- MSD Manuel Professional Version. Overview of Glaucoma. https://www.msdmanuals.com/professional/eye-disorders/glaucoma/overview-of-glaucoma?query=glaucoma. Accessed August 10, 223.
- MSD Manuel Professional Version. Cataract. Cataract – Eye Disorders – MSD Manual Professional Edition (msdmanuals.com). Accessed August 10, 2023.
- NHS. Diabetic Retinopathy. https://www.nhs.uk/conditions/diabetic-retinopathy/. Accessed 11 August, 2023.
- Bone K, Mills S. Principles And Practice Of Phytotherapy. China: Churchill Livingstone Elsevier; 2000.
- Bone, K, The Ultimate Herbal Compendium. Warwick, Queensland: Phytotherapy Press; 2007.
- Paduch R, Woźniak A, Niedziela P, Rejdak R. Assessment of eyebright (euphrasia officinalis L.) extract activity in relation to human corneal cells using in vitro tests. Balkan Med J. 2014;31(1):29-36. doi:10.5152/balkanmedj.2014.8377.
- Frawley D, Lad V. The Yoga of Herbs. 2nd ed. Twin Lakes: Lotus Light Publications; 2008.
