What is eye cancer?

Eye cancer is a general term that includes different cancer types. 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 cancer is

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.

Normally, cells only divide to replace old and worn out cells. Cancer develops when something inside a single cell goes wrong, making the cell carry on dividing until it forms a lump or 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

The uveal layer is the most common place for eye cancers to start.

The most common type of cancer to affect 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 accessory or 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 850 cases are diagnosed in the UK every year. 

Who gets it

Overall, the risk of developing an eye cancer increases as you get older. Almost 25 out of 100 people (almost 25%) 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.