Eye cancer is a malignant tumour that starts in the cells of the eyeball or the surrounding tissues. Malignant means that it can spread, or metastasize, to other parts of the body.
The eye is the organ that lets you see. The eyeball, or globe, is the main part of the eye. It includes the iris, which is the coloured part of your eyeball, and the pupil, which is the black part that lets light into the eye. The eyeball sits in and is protected by the orbit, or eye socket. The orbit is made of bone and other tissues. The eye also has other parts called accessory, or adnexal, structures. These include the eyelid, conjunctiva and glands.
Cells indifferent parts of the eyeball or surrounding tissues sometimes change and no longer grow or behave normally. These changes may lead to non-cancerous, or benign, tumours such as choroidal hemangioma, pterygium or benign lacrimal gland tumour.
Changes to cells in the eyeball or surrounding tissues can also cause precancerous conditions. This means that the cells are not yet cancer but there is a higher chance these abnormal changes will become cancer. The most common precancerous condition of the eye is an atypical mole, or dysplastic nevus.
In some cases, changes to cells in the eye can cause cancer. Cancer that starts in the eyeball or surrounding tissues isn’t very common in adults. When eye cancer does occur in adults, it starts most often in melanocytes. These cells make melanin, which is a pigment that gives the eyes, skin and hair their colour. Tumours that develop inside the eyeball are called intraocular tumours. Cancer that starts in melanocytes inside the eyeball is called intraocular melanoma.
Adults can also develop other types of cancer that start in the different types of cells in the eyeball or surrounding tissues. These cancers include ocular lymphomas, orbital tumours, conjunctival tumours, lacrimal gland tumours and eyelid tumours.
Retinoblastoma is the most common eye cancer that occurs in children. It starts in the cells of the retina. Find out more about retinoblastoma.
Other types of cancer can spread to the eyeball or the surrounding tissues. Cancer that starts in another part of the body and spreads to the eyeball or surrounding tissues is called eye metastasis. It is more common than cancer that starts in the eyeball or surrounding tissues, which is called primary eye cancer. Eye metastasis isn’t treated in the same way as primary eye cancer. Most often, cancer spreads to the eye from the breast, lung or gastrointestinal (GI) tract.
The Canadian Cancer Society is actively lobbying the federal government to establish a national caregivers strategy to ensure there is more financial support for this important group of people.