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A Review of The Structures of the Eye
What is it?
Glaucoma is an umbrella term encompassing many different disease states affecting all ages. One can be born with certain types of glaucoma. What we commonly encounter though is ‘primary open angle glaucoma’. This is usually a disease of the middle aged and elderly populations and is the commonest cause of preventable blindness in New Zealand and other developed countries (GlaucomaNZ, n.d.).
In these diseases, the delicate nerves that gather from all over the retina to exit the eye via the optic nerve, are damaged. This results in progressive loss of these nerves.
Normal Retin, retinal arteries leaving and veins entering the optic nerve head. The salmon coloured ring is made up of the nerve fibers from the retina leaving the eye to enter the brain.
The nerves that govern the outer/ peripheral field of vision, are affected first. This leads to a progressive closing in of the visual field towards tunnel vision. It happens very slowly and unfortunately many patients adapt to the changes and are unaware of it. In this situation, one might not see a child waiting to cross the road, a cyclist in the cycle lane or a car approaching from a side road.
Visual field by Harry Moss Traquair in his book “Clinical Perimetry” (1938; modified) showing that it is larger on the temporal side than on the side adjacent to the nose. The numbers are the degrees of arc from the centre of the field. By Strasburger - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=54372870
Eventually they experience sudden blindness, when finally that last nerves delivering signals from the central vision (which one uses to read, watch TV, use to recognise faces and sense colour) are affected. These effects are irreversible. Most people have no symptoms and no early warning signs and it is estimated that 50% of people with glaucoma do not realise they have it (GlaucomaNZ, n.d.).
By Snoop, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=3411626
There are many factors that contribute to this nerve damage and only one of those factors is in pressure in the eye.
Eye Pressure
There may be a mismatch between the production of fluid in the front chamber of the eye and the outflow. In primary open angle glaucoma, the drainage channels become clogged and or the tissues around the channels harden and the channels scar up and close. This results in the pressure in the eye increasing because the fluid cannot drain out of the eye. This extra pressure damages the nerves as they pass over the brim of the optic nerve opening.
Variation between people
There are other factors that play a role and contribute for example one person may have the same pressure in the eye as a person with glaucoma and yet have no damage. These patients are labeled as having ocular hypertension (OHT) meaning that they have higher than normal pressure, but no damage is being done.
Normal Tension Glaucoma
There is a subtype in which the pressure is within normal limits, but the nerves cannot withstand that pressure. This is known as normal tension glaucoma (NTG). There are many studies that have investigated what is happening in this subset of patients and there are many contributing factors including the blood flow and the reactivity of blood vessels not only in the eye, but around the body. People with Raynaud’s Syndrome and migraine can fall within this group.
Blood Flow
The blood flow and things that effect it including dietary and environmental factors also impacts on the degree to which damage is done to the nerve rim. Some people have only slightly higher pressures than normal, but still suffer from the consequences.
Immunity and inflammation
More recent interest and research into glaucoma and it’s causes have investigated autoimmunity as part of the pathology and many complex factors that help to protect nerves of the eyes.
Risk Factors for Glaucoma: Who Gets It? (American Academy of Ophthalmology, 2019)
People
with a family history of glaucoma
with diabetes
who are over age 40
who are of African, Hispanic, or Asian heritage
who have high eye pressure
who are long sighted or short sighted
who have had an eye injury
who use long-term steroid medications
suffer from migraine
suffer from high blood pressure
who have poor blood circulation or other health problems affecting the whole body
Glaucoma NZ states that “People with risk factors for glaucoma may need more frequent eye examinations than the standard. Over 90 per cent of the adult population needs eye examinations at the age of 40 and five-yearly thereafter (GlaucomaNZ, n.d.). If you have risk factors then you should visit your optometrist more regularly under their advisement depending on your level of risk and the examination findings.
Treatments
If caught early, most people are successfully treated but will need lifetime treatment with eye drops to control the pressure. A smaller number will need other interventions such as laser surgery or open surgery in theatre.
What Can You do About it?
In most circles, this is considered a chronic disease that only eye drops and or surgery can control. However, there are reams of research articles on the subject of nutritional status, diets, foods, nutrients, herbs and supplements, exercise, lifestyle, body mass index (obesity) and more that both worsen and improve eye pressure and glaucomatous damage. There are a great many foods and factors that harm and a great many foods, nutrients, supplements and herbs that help!
It is within your power to affect your long term visual outcome. Taking care of many individual aspects of your general health many of them seemingly unrelated to the eye impacts enormously on the progression of your glaucoma damage, how many drops you might need to control the pressure and whether you might need laser or surgery.
How can I help?
I shall provide you with a breakdown of your contributing factors and create a plan for you as an individual to start to minimise them.
Even people who haven’t got diabetes can still look after their blood sugars and insulin levels. You can control allergies and other immune issues. Some researchers have found evidence that immune reactions and inflammation play a contributory role in glaucoma.
There is a lot one can do to improve blood flow to the eye as well as to the rest of the body.
There are foods and herbs that are neuroprotective (protect nerve tissue).
I am a firm believer in patient education and I can help to explain what your lead ophthalmologist is doing, planning and suggesting to you. My aim is to back them up in their care and ensure that together we are doing everything we can to improve your eye health.
Contact me to arrange your personal consultation.
