What is Glaucoma?
Glaucoma is the name for a group of eye conditions in which the optic nerve is damaged to the point where it leaves the eye. Your eye needs a certain amount of pressure to keep the eyeball in shape so it can work properly.
In some cases the damage is caused by raised eye pressure. Other cases may be due to a weakness in the optic nerve. In most cases both factors are involved to a varying extent. Eye pressure is largely independent of blood pressure.
What controls pressure in the eye?
A layer of cells behind the iris (the coloured part of the eye) produces a watery fluid - aqueous - If the aqueous fluid cannot leave the eye through its natural drainage channels, or too much is produced your eye pressure will rise.
Why can increased eye pressure be serious?
If the optic nerve comes under too much pressure it can be injured. A really high pressure will damage the optic nerve immediately. A lower level of pressure can damage more slowly, and then you would gradually lose your sight if it is not treated.
Chronic glaucoma
The most common form of glaucoma. The eye pressure rises very slowly and the field of vision gradually becomes impaired.
Acute glaucoma
This is much less common and can happen suddenly and can be quite painful and will cause permanent damage to your sight if not treated promptly.
Secondary and developmental glaucoma
When a rise in eye pressure is caused by another eye condition this is called secondary glaucoma. There is also a rare but potentially serious condition in babies called developmental or congenital glaucoma which is caused by malformation in the eye.
People more at risk of chronic glaucoma
- Age: Chronic glaucoma becomes more common with increasing age. It is uncommon below the age of 40.
- Race: People of African origin are more at risk of chronic glaucoma; it may come on somewhat earlier and be more severe.
- Family: If you have close relatives with glaucoma, you should have regular eye examinations, and recommend other family members do the same. This is important if you are aged 40 or over. Patients in this category are entitled to a free NHS eye examination
- People with a high degree of short sight are more prone to chronic glaucoma.
- Diabetes is also believed to increase the risk of developing this condition.
How is chronic glaucoma detected?
The condition is detected by most Opticians during an eye examination by conducting a number of tests:
- viewing your optic nerve by shining a light from a special electric torch into your eye
- measuring the pressure in the eye using a special instrument
- being shown a sequence of spots of light on a screen and asked to say which ones you can see
- having a photograph taken with a retinal imaging camera
How is chronic glaucoma treated?
The main treatment aims to reduce the pressure in your eyes, and in some cases improve the blood supply to the optic nerve. Treatment is usually started with eye drops. In some cases laser treatment or an operation may be necessary.
Although early damage cannot be repaired, with early diagnosis and treatment, damage can be kept to a minimum and good vision can be enjoyed indefinitely.
What are the symptoms of acute glaucoma?
The eye can suddenly become very painful and red, the sight deteriorates and may even black out, also there could be nausea and vomiting. You may also see misty rainbow coloured rings around white lights. Mild attacks can occur with vision seeming 'misty' with coloured rings seen around white lights and some discomfort in the eye. You should contact your GP without delay if you experience any of these symptoms.
What is the treatment?
If you have an acute attack you will need to go into hospital immediately and given drugs so that the pain and pressure can be relieved. You may also be advised to have laser treatment or an operation.
If treated promptly and effectively there may be almost complete and permanent recovery of vision. Occasionally the eye pressure may remain a little raised and that treatment is required as for chronic glaucoma.
