Glaucoma is the name for a group of eye conditions at which the optic nerve is damaged at the point where it leaves the eye.
What is glaucoma?
The nerve carries information from the light sensitive layer in your eye, the retina, to the brain where it is perceived as a picture.Your eye needs a certain amount of pressure to keep the eyeball in shape so it can work properly. In some people, the damage is caused by raised eye pressure.
Others may have an eye pressure with in normal limits but the damage occurs because there is a weakness in the optic nerve. In most cases both factors are involved but to a varying extent. Eye pressure is largely independent on blood pressure.
Why can increased eye pressure be serious?
If the optic nerve comes under too much pressure then it can be injured, How much damage there is will depend on how much pressure there is and how long it has lasted. 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 were not treated.
Are there different types of glaucoma?
Chronic glaucoma : The most common is chronic glaucoma (chronic = slow) in which 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 glaucoma (acute = sudden) is much less common in western countries. This happens when there is a sudden rise in eye pressure. This can be quite painful and will cause permanent damage to your sight if not treated promptly.
How common is glaucoma?
In the UK some form of glaucoma affects about 2 in 100 people over 40.
Are some people particularly at risk of chronic glaucoma?
Yes, there are several factors, which increase the risk
AGE : Chronic glaucoma becomes much more common with increasing age. It is uncommon below the age of 40 but affects one percent of people over this age and five percent of people over 65.
RACE : If you are of African origin you are more at risk of chronic glaucoma and it may come on somewhat earlier and more severe.
FAMILY : If you have a close relative that has chronic glaucoma then you should have an eye test every year. You should advise other members of your family to do the same.
This is especially important if they aged over 40. Please note: People over the age of 40 years and with a family history of glaucoma-such as parents, children, or siblings of people diagnosed with glaucoma- are entitled to a free sight test every two years under the NHS.
How can chronic glaucoma be serious risk to sight?
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 the sight would be lost.
How is chronic glaucoma treated?
The main treatment for chronic glaucoma aims to reduce the pressure in the eye. You will need to go to hospital for treatment and have regular check-ups afterwards.
Treatment to lower pressure is usually started with eye drops. If this does not help, your specialist may suggest either laser treatment or an operation called trabeculectomy to improve the drainage of fluids from your eye.
What is acute glaucoma?
In acute glaucoma the pressure in the eye rises rapidly. This is sometimes called closed angle glaucoma. The sudden increase in eye pressure can be very painful.
The affected eye becomes red,the sight deteriorates and may even black out. There may also be nausea and vomiting. In the early stages you may see misty rainbow coloured rings around white lights. Sometimes people have a serious of mild attacks, often in the evening. Vision may seem ‘misty’ with coloured rings seen around white lights and there may be some discomfort in the eye.
Useful What is the treatment?
If you have an acute attack you will need to go into hospital immediately so that the pain and the pressure in the eye can be relieved. Drugs will be given to reduce the pressure.
When the pain and inflammation have gone down, your surgeon will advise making a small hole in the outer border of the iris to relieve the obstruction, allowing the fluid to drain away.
This is usually done by laser treatment or by a small operation. Usually the surgeon will also advise you to have the same treatment on the other eye, because there is a high risk that it will develop the same problem. This treatment is not painful.
Will I be able to drive?
Most people can still drive if the loss of visual field is not to advances. To assess possible damage to your peripheral vision you will a special test to see whether your sight meets the standards of the driver and Vehicle Licensing Authority. This is available at Opticare Opticians (Newark branch)
What if my sight cannot be fully restored?
Early detection and treatment will usually prevent or retard further damage by glaucoma. Much can be done to help you use your remaining vision as fully as possible.
Ask us about low vision aids and whether you are eligible to register as partially sighted or blind. Registration opens the door to expert help and sometimes to financial benefits.