What is Glaucoma?
Glaucoma is the name given to a group of eye diseases in which the optic nerve at the back of the eye is slowly destroyed. In most cases this is due to an increased pressure inside the eye, termed ‘ocular hypertension’. The increased pressure is in the fluid of the eye (aqueous humour), resulting from blockage of the circulation of this fluid or its drainage. Much less commonly, the damage to the optic nerve may be caused by poor blood supply to the optic nerve fibres. The damage to the optic nerve causes peripheral vision loss. It can progress to complete blindness if untreated.
Raised intraocular pressure is a significant risk factor for developing glaucoma (above 21 mmHg or 2.8 kPa). One person may develop nerve damage at a relatively low pressure, while another person may have high eye pressure for years and yet develop no nerve damage.
There are two main categories of glaucoma, ‘open angle’ and ‘closed angle’ glaucoma. Open angle, chronic glaucoma tends to progress slowly and the loss of vision may not be noticed until the disease has progressed significantly. Closed angle can appear suddenly and is often painful and visual loss can progress quickly.
According to Glaucoma Australia, over 300,000 Australians have glaucoma. While it is more common as people age, it can occur at any age. As our population becomes older, the proportion of glaucoma sufferers is increasing.
Symptoms of Open-angle Glaucoma
Open-angle or chronic glaucoma is the most common form (about 90% of cases). It is painless and does not have acute attacks. It has no symptoms until eye sight is lost at a later stage. There is, in fact, progressive visual field loss and optic nerve changes (increase in cup-to-disc ratio on fundoscopic examination - looking at the back of the eye with an ophthalmoscope). The damage advances very slowly and destroys vision gradually, starting with the side or peripheral vision. One eye covers for the other, and the person remains unaware of any problem until the majority of nerve fibres have been damaged, and a large part of the vision has been destroyed. This damage is irreversible. Treatment cannot recover that which has been lost.
For this reason it is so important to detect the problem as early as possible, to be able to start treatment with as little damage to the vision as possible.
Symptoms of Closed-angle Glaucoma
Closed-angle glaucoma accounts for less than 10% of glaucoma cases. Many present with sudden ocular pain, seeing halos around lights, red eye, very high intraocular pressure (>30 mmHg), nausea and vomiting. There is sudden decreased vision. It is an ocular emergency.
Risk Factors for Glaucoma
Although anyone can get glaucoma, some people have a higher risk. Higher risk factors include:
· Age: elderly people have a higher risk for open-angle glaucoma
· A family history of glaucoma
· African and East Asian descent
· The presence of diabetes
· Past or present use of cortisone drugs (steroids)
· Long and short sightedness
· Eye injury
People with higher risk should have their first eye check no later than the age of 35. For most people, it is recommended to have an eye check for glaucoma by the age of 40.
Diagnosis of Glaucoma
Screening for glaucoma is usually performed as part of a standard eye examination performed by ophthalmologists and optometrists. Testing for glaucoma should include measurements of the intraocular pressure via tonometry, changes in the shape of the eye, anterior chamber angle examination, and examination of the optic nerve to look for any visible damage to it, or change in the cup-to-disc ratio. A visual field test should also be performed.
Treatment for Glaucoma
The goals of glaucoma management are to avoid glaucomatous damage to the optic nerve and preserve visual field and total quality of life for patients, with minimal side effects.
Intraocular pressure can be lowered with medication, usually eye drops. Several different classes of medications are used to treat glaucoma, with several different medications in each class. Once a diagnosis has been made, the management must be supervised by a specialist physician who will determine the appropriate medication (usually as eye drops). Glaucoma drugs include:
· Prostaglandin analogues
· Carbonic anhydrase inhibitors
· Beta-adrenergic receptor antagonists
· Alpha2-adrenergic agonists
· Miotic agents
· Less selective sympathomimetics, such as epinephrine.
Poor compliance with medications and poor compliance with follow-up visits are major reasons for further vision loss once a diagnosis has been made.
Both laser surgery and conventional surgery can be performed to treat glaucoma. Generally, these operations are a temporary solution, as there is not yet a cure for glaucoma. Again, the type of surgical intervention is the decision of the specialist.
Diet, Herbal and Dietary Supplements in the Management of Glaucoma
In summary, glaucoma is a condition in which the eye’s intraocular pressure is too high. This means that the eye has too much aqueous humour in it. Glaucoma occurs when pressure builds up in the eye from excess fluid.
The following may assist in reducing intraocular pressure:
· Omega-3 fatty acids
· Alpha lipoic acid
· Limiting alcohol intake
· No smoking
· Normal Body Mass Index (BMI less than 25)
· Ginkgo biloba
· A healthy diet made up of 75-80% alkali-forming foods.
There are a number of vitamins, minerals and herbal supplements that are considered to be essential for eye health. They are said to play a critical role in the support of healthy eyesight, as well as protecting against potentially blinding conditions such as glaucoma, macular degeneration and cataracts.
www.eyevitaminhealth.com sets out details of how (the mechanism by which) 17 vitamins, minerals and herbal supplements contribute to eye health. It is not suggested that all 17 be taken! However a selection from the list should be considered as a supplement for better eye health. The 17 are listed alphabetically and not in any order of importance:
· Alpha-lipoic acid
· Copper gluconate
· Eyebright (herb)
· Ginkgo biloba
· Lutein (containing Zeaxanthin)
· N-acetyl cysteine (NAC)
· Vitamin A
· Vitamin C
· Vitamin E
Prevention is always the best way forward. Aim to maximise eye health with a healthy diet (see my March 2009 newsletter Foods for Health) and a selection of the vitamins, minerals and herbal supplements as listed above.
Be aware of the possibility of glaucoma. It has been called the “silent thief of sight” and the “sneak thief of sight”. Be tested regularly, especially in the presence of risk factors, and when treatment is indicated, be fully compliant.
*Copyright 2012: The Huntly Centre.
Disclaimer: All material in the huntlycentre.com.au website is provided for informational or educational purposes only. Consult a health professional regarding the applicability of any opinions or recommendations expressed herein, with respect to your symptoms or medical condition.
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