Glaucoma is damage to optic nerve at the point where it leaves the eye. Your eye needs a certain amount of pressure from fluid in the eye to keep the eyeball in shape to work properly. Any change in pressure leads to damage of the nerve. Damage will depend on the extent of the pressure, the length of time it has lasted, and whether there is a poor blood supply or other weakness of the optic nerve. In the UK some form of glaucoma affects about 2 in 100 people over the age of 40.
- Sight is weaker in one eye than the other or generally, more weaker overall.
- Vision becomes weaker generally or, when looking straight ahead, you can see the shape of an arc a little above and/or below the centre.
- Tunnel vision
- For rarer cases of actue glaucoma, the affected eye may become red, or you may see misty rainbow coloured rings around white lights or just a sudden deterioration in sight. There may also be nausea and vomiting.
- The most common is chronic glaucoma (chronic = slow) in which the eye’s drainage channels become blocked over many years. The eye pressure rises very slowly and there is no pain to show there is a problem, but the field of vision gradually becomes impaired.
- Acute glaucoma (acute = sudden) is a sudden and complete blockage to the drainage channels. It is much less common and would be noticeably painful.
- Secondary Glaucoma is when a rise in eye pressure is caused by another eye condition.
- There is also a rare but sometimes serious condition in babies called developmental glaucoma which is caused by a malformation in the eye.
Most At Risk
- Age – Chronic glaucoma becomes much more common with increasing age. It is uncommon below the age of 40 but affects one per cent of people over this age and five per cent over 65.
- Race – If you are of African origin you are more at risk of chronic glaucoma: it may occur earlier in life and be more severe.
- Family – If you have a close relative who has chronic glaucoma then you should have regular eye exams, particularly if you are over 40.
- Short sight - People with a high degree of short sight are more prone to chronic glaucoma.
- Diabetes is believed to increase the risk of developing this condition.
There are three tests to diagnose glaucoma. Each one is simple, quick, lasting around 10 minutes each, and painless.
- Viewing your optic nerve either with digital retinal photographs or using a special lens and microscope designed to give a 3D view of the back of the eye.
- Measuring the pressure in the eye using a special instrument.
- Visual field test – where you are shown a sequence of spots of light on a screen and asked to say which ones you can see.
Usually provided at hospital, eyedrops are administered to reduce the pressure in the eye. These reduce the amount of fluid produced in the eye or open up the drainage channels so that excess liquid can drain away. If this does not help, an eye surgeon may suggest either laser treatment or an operation called a trabeculectomy where a small hole is made in the outer border of the iris to relieve the obstruction and drain excess fluid. Some treatments also aim to improve the blood supply of the optic nerve. Depending on circumstances and the response to treatment, it may not require an overnight stay.
For cases of acute glaucoma, a trip to hospital is also essential where, once the pain and inflammation has been treated, laser treatment or by a small operation called a trabeculetomy (above) can be performed. Treatment is usually provided to both eyes as there is a high risk the unaffected eye may develop the same problem.
Ongoing examinations are likely to be annual. In the event there is irreparable damage, we will help you use your remaining vision as fully as possible. Optometrists offer advice on low vision aids and eligibility to register as partially sighted or blind which can offer additional expert help and, where applicable, financial benefits.
Frequently Asked Questions
Our team of optometrists have a strong track record in diagnosing and treating glaucoma patients. We have put together a list of frequently asked questions based on patient queries over the years.
Will I be able to drive?
Most people can still drive if the loss of visual field is not advanced. However patients are encouraged to sit a special test to see whether your sight meets DVLA standards.
What controls pressure in the eye?
A layer of cells behind the iris (the coloured part of the eye) produces a watery fluid, called aqueous. The fluid passes through a hole in the centre of the iris (called the pupil) to leave the eye through tiny drainage channels. These are in the angle between the front of the eye (the cornea) and the iris and return the fluid to the blood stream. Normally the fluid produced is balanced by the fluid draining out, but if it cannot escape, or too much is produced, then your eye pressure will rise. (The aqueous fluid has nothing to do with tears.)
Why can increased eye pressure be serious?
If the optic nerve comes under too much pressure then it can be damaged. How much damage there is will depend on how much pressure there is and how long it has lasted, and whether there is a poor blood supply or other weakness of the optic nerve. A really high pressure will damage the optic nerve immediately. A lower level of pressure can cause damage more slowly, and then you would gradually lose your sight if it is not treated.
How common is glaucoma?
In the UK some form of glaucoma affects about 2 in 100 people over the age of 40.
Why can chronic glaucoma be a serious risk to sight?
The danger with chronic glaucoma is that your eye may seem perfectly normal. There is no pain and your eyesight will seem to be unchanged, but your vision is being damaged. Some people do seek advice because they notice that their sight is less good in one eye than the other.
The early loss in the field of vision is usually in the shape of an arc a little above and/or below the centre when looking ‘straight ahead’. This blank area, if the glaucoma is untreated, spreads both outwards and inwards. The centre of the field is last affected so that eventually it becomes like looking through a long tube, so-called ‘tunnel vision’. In time even this sight would be lost.
Can chronic glaucoma be cured?
Although damage already done cannot be repaired, with early diagnosis and careful regular observation and treatment, damage can usually be kept to a minimum, and good vision can be enjoyed indefinitely.
Further help and information
- The International Glaucoma Association supports patients by providing information, so that they can co operate fully in their treatment and prevent sight loss. It also promotes awareness and early detection of glaucoma, and supports and carries out research. The International Glaucoma Association (IGA), Woodcote House, 15 Highpoint Business Village, Henwood, Ashford, Kent, TN24 8DH. Telephone 01233 64 81 70 01233 64 81 70 Available for advice by letter or by telephone 10am – 5pm from Monday to Friday.
- The Partially Sighted Society offers information and advice, publications, aids to vision, enlargement services and local support to help you make the most of your vision. Contact: The Partially Sighted Society, The Sight Centre 9 Plato Place, 72-74 St Dionis Road, London SW6 4TU. Telephone 0207 371 0289 0207 371 0289
- Royal National Institute for the Blind, 224 Great Portland Street, London W1N 6AA Telephone
Contact us at the practice for expert information and professional advice about glaucoma or any aspect of vision or eye health.
0131 225 2235