Giant cell arteritis is a condition which affects the arteries. If left untreated it can cause serious sight loss.
We need light to see what is around us and to see colour. Light bounces off the objects we look at. These reflect different amounts of light which we see as different colours.
Light rays enter the front of our eye through the clear cornea and lens. It is very important that both the cornea and lens are clear as this allows the light to pass directly through the front of the eye to the retina.
The cornea and lens bend light so that it can focus on the retina at the back of our eye. This gives us a clear, precise image. The cornea focuses the light towards our retina. The lens fine tunes the focussing of this light.
Our tears form a protective layer at the front of the eye and also help to direct the light coming into our eye.
The iris, the coloured circle at the front of our eye, changes the size of the pupil which allows different amounts of light into our eye.
The pupil is the dark hole in the middle of the coloured part of our eye. The pupil gets smaller in bright conditions to let less light in. The pupil gets bigger in dark conditions to let more light in.
The middle of our eye is filled with a jelly-like substance called the vitreous. The vitreous is clear and allows light to pass directly from the front to the back of our eye.
The retina at the back of the eye is a light-sensitive layer which consists of rod and cone cells. These cells collect the light signals directed onto them and send them as electrical signals to the optic nerve at the back of our eye.
Rod cells are concentrated around the edge of the retina. They help us to see things that aren't directly in front of us, giving us a rough idea of what is around us. This helps with mobility and getting around by stopping us from bumping into things. Rod cells also enable us to see things in dim light and to see movement.
Cone cells are concentrated in the centre of the retina where the light is focused by the cornea and lens. This area is called the macula. Cone cells give us our detailed vision which we use when reading, watching TV, sewing and looking at people's faces. They are also responsible for most of our colour vision.
The optic nerve is made up of thousands of nerve fibres. These fibres pass electrical signals along to our brain where they are processed into the image we are looking at.
Seeing can be likened to the process of taking pictures on a film with a camera which you then get developed. The retina is like a camera film which stores an image of what we are looking at. The image directed onto the retina is then sent along to the brain where it is processed, like developing a camera film. Therefore we actually "see" in our brain with the light information sent to it from our eyes. This whole process happens very quickly so that everything we see is in focus.
Arteries are blood vessels which take fresh blood to all the parts of the body. With giant cell arteritis the medium-sized blood vessels become swollen. The most common artery to swell is the temporal artery.
The temporal artery provides blood to the optic nerve. The danger to sight occurs because the artery can become so swollen that it is easily blocked. If this happens then the optic nerve is starved of blood and sight can be lost.
At the moment the exact cause of the disease is unknown.
It usually only affects people over the age of 55 and is most common in people over 75. Giant cell arteritis seems to affect more women than men.
Giant cell arteritis is sometimes related to other problems. Most commonly polymyalgia rheumatica, this is a condition which causes pain in the shoulders and hip joints. Polymyalgia rheumatica is also associated with problems of blood supply. Often people with polymyalgia rheumatica go on to develop giant cell arteritis. However, giant cell arteritis can often occur on its own without any other medical conditions.
Often the first sign of giant cell arteritis is pain on chewing. Often people are able to chew for a while but eventually the pain, becomes so bad they have to stop. If this happens you should be seen at the hospital as soon as possible.
Sometimes the first sign that someone has giant cell arteritis is a headache. This headache is usually concentrated in the temple region of your head. Just above your eye and near to your hairline. Often it is tender to touch and things like combing your hair may be painful.
Sometimes the temporal artery swells and can be seen around your eye, this too is tender to touch. There are other symptoms such as fever, weight loss and generally feeling unwell.
If you develop pain on chewing or a new kind of headache especially in the temple area, which is more often painful than not, you should see your GP.
Giant cell arteritis causes the artery walls to swell which means that the space the blood has to travel through becomes thinner. Sometimes the artery develops sticky patches which collect cells from the blood, making the tunnel even thinner. If left untreated, these sticky patches can interfere with the amount of blood passing through the arteries. This can cause the artery which brings blood to the optic nerve to swell, reducing the amount of fresh blood the optic nerve receives. Unfortunately this can cause the optic nerve to become damaged by the lack of fresh blood. This can have a serious affect on vision. It can cause people to lose all the sight in one eye.
Luckily giant cell arteritis can be treated before it gets to this stage. If you go to your GP with a new headache in the front part of your head along with some of the other symptoms mentioned, they may well send you to the hospital. An ophthalmologist (eye specialist) can then confirm a diagnosis and prescribe a course of treatment that should prevent sight loss.
As well as taking a history from you about how the condition is affecting you, the doctor may well perform a number of tests. They will take a blood sample to determine your ESR. ESR stands for erythrocyte sedimentation rate. This measures the consistency of your blood.
A normal rate is your age divided by two. So someone 60 years old ESR should be around 30, anything higher than 50 is considered a sign that there is some kind of swelling in the body which might mean giant cell arteritis.
There is also another blood test called the CRP (C reactive protein) that is often performed. This test measures the level of a protein in the blood which is only present when there is acute swelling in the body. This means it is a good indication for swelling caused by giant cell arteritis.
The ophthalmologist may well also perform a biopsy on your swollen temporal artery. This involves a small operation which can be performed as an outpatient. Using a local anaesthetic, the doctor removes a small part of your artery and examines it under a microscope. With this they can see whether giant cell arteritis has affected your artery and confirm your diagnosis.
If giant cell arteritis is caught early it can be treated with steroid tablets. Steroids help to reduce swelling, this mean that the swelling in the arteries can be reduced. The blood can then flow freely to the optic nerve again. This prevents the loss of vision.
The steroid treatment is started at a high dose and is reviewed closely. Over a period of time, sometimes a long period, the dose of the steroids can be reduced so that eventually you can stop taking them or control the disease on a very low dose.
Sometimes if the symptoms of giant cell arteritis are missed then people can suddenly lose sight in one eye. If this happens most people go straight to casualty since it is obvious that something is wrong. There they will see an ophthalmologist who will prescribed high dose of steroids usually intravenously (through a drip) this means you have to stay in hospital.
The high dose steroids are an attempt to bring down the swelling in the hope that re-establishing the blood supply quickly can bring sight back. Usually however this sight loss is permanent and the steroids are being used to stop the giant cell arteritis affecting the sight in the other eye.
Giant cell arteritis is a condition that can seriously affect vision, although only about 25 per cent of cases will cause the sight loss described if left untreated.
It is better not to take any risk. Any new pain on chewing, persistent headache, symptoms such as the swelling of the artery or pain when touching the temples should be reported to your GP.
This means that you can get the steroid treatment promptly and not risk the loss of your sight.
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Polymyalgia Rheumatica and Giant Cell Arteritis UK (PMRGCA UK)
Offers information and support, raises awareness and encourages research into polymyalgia rheumatica and giant cell arteritis. More details available from the PMRGCA UK website.
Offers information and support to sufferers and carers of people with polymyalgia rheumatica and giant cell arteritis in Scotland. More details available from the PMR-GCA Scotland website
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