What is eye cancer?
Eye cancer includes different types of cancer. The type of cancer you have depends on the type of cell it starts in. There are different parts of the eye, and some of these are more likely to get cancer than others.
What is cancer?
Your body is made up of billions of cells that can only be seen under a microscope. The cells group together to make up the tissues and organs of our bodies.
Usually, we have just the right number of each type of cell. This is because cells produce signals to control how much and how often the cells divide. If any of these signals are faulty or missing, cells might start to grow and multiply too much and form a lump called a tumour.
A tumour can be either non cancerous (benign) or cancerous (malignant). A benign tumour does not spread to other parts of the body. But a malignant tumour (cancer) can spread.
The different parts of the eye
There are two main areas to the eye – the front of the eye and the back.
The eyeball
The eyeball has three layers sandwiched together:
- the outer white fibrous layer, the sclera
- the middle blood rich layer, the choroid
- the inner coloured (pigmented) layer, the retina
The inside of the eyeball is filled with a clear jelly like substance called vitreous humour. This, and the fibrous white sclera help to keep the shape of your eyeball.
The blood vessels that run through the choroid carry food and oxygen to the cells of the eye.
The retina lines the inside of the eyeball. This is the nerve layer of the eye. The cells of the retina react to light and send messages to the brain through the optic nerve. This makes it possible for you to see.
The front of the eye
The front of the eye is the bit you can see.
A thin, clear, moist membrane called the conjunctiva coats the inner surfaces of the eyelids and the outer surface of the eye.
The three layers of the eyeball continue round but they make up different structures in the front of the eye. The fibrous sclera becomes clear, instead of white. This part of it is called the cornea and covers your pupil and iris.
The middle choroid layer becomes the iris and the ciliary body. The iris is the coloured part around your pupil that covers the lens of the eye. It controls how much light enters your eye.
The ciliary body lies just behind the iris. It has two functions. It is the muscle that controls the focusing of the eye. And it makes the clear fluid (aqueous humour) that fills and shapes the front of your eye.
The uvea
The middle layer of the eye is called the uvea. This includes the:
-
iris and ciliary body at the front (anterior) of the eye
-
choroid at the back (posterior) of the eye
In the UK, the choroid in the uveal layer is the most common area for eye cancers to start.
The most common type of cancer that affects the uvea is melanoma. Melanoma develops in cells called melanocytes, which are found in our skin, lips, and the lining of organs such as the eye. You may hear your doctor talk about uveal, iris, ciliary body or choroidal melanomas.
The tissues surrounding the eyeball (orbit)
The orbit is the eye socket that contains the tissues surrounding the eyeball. These include:
- muscles that allow the eyeball to move in different directions
- nerves attached to the eye
- fat that cushions the eyeball
Cancers in this part of the eye are called orbital cancers. They are very rare.
Structures around the eye
Structures around the eye include the eyelids and tear glands (lacrimal glands). They are called adnexal structures. So doctors call cancers that develop in these tissues adnexal cancers.
Secondary eye cancers
Cancer that starts in the eye is called primary eye cancer. This section is about primary eye cancer.
Sometimes cancer can spread to the eye from another part of the body. This is called secondary eye cancer. In women this is most likely to happen with breast cancer, and in men this is most likely to happen in lung cancer.
If your cancer has spread to the eye, go to information about your primary cancer.
How common is eye cancer?
Eye cancer is very rare. Around 880 cases are diagnosed in the UK every year.
Who gets eye cancer?
Overall, the risk of developing eye cancer increases as you get older. More than 20 out of 100 people (more than 20%) diagnosed with eye cancer in the UK are aged 75 and over. The exception to this is a type called retinoblastoma. This usually affects children under the age of 5.
