Eye Cancer

What is eye cancer?
An eye cancer is a cancer that starts in the eye. There are different types of eye cancers. To understand eye cancers, it helps to know something about the normal structure and function of the eye.

Parts of the eye

The eye has 3 major parts: the eyeball (globe), the orbit, and the adnexal structures.

Eyeball

The main part of the eye is the eyeball (also known as the globe), which is mostly filled with a jelly-like material calledvitreous humor. The eyeball has 3 main layers: the sclera, the uvea, and the retina.

Sclera: The sclera is the tough, white tissue that covers most of the outside of the eyeball. In the front of the eye it is continuous with the cornea, which is clear to let light through.

Uvea: The uvea is the middle layer of the eyeball. It is where most melanomas of the eye develop. The uvea has 3 main parts:

• The iris is the part of the eye that gives it color (like blue or brown). It surrounds the pupil, the small opening that allows light to enter the eyeball.
• The choroid is a thin, pigmented layer lining the eyeball that nourishes the retina and the front of the eye with blood.
• The ciliary body contains the muscles inside the eye that change the shape of the lens so that the eye can focus on near or distant objects. It also contains cells that make aqueous humor, the clear fluid in the front of the eye between the cornea and the lens.

Retina: The retina is the inner layer of cells in the back of the eye. It is made up of specialized nerve cells that are sensitive to light. These light-sensing cells are connected to the brain by the optic nerve. Light enters the eye and passes through the lens, which focuses it on the retina. The pattern of light (image) appearing on the retina is sent through the optic nerve to an area of the brain called the visual cortex, allowing us to see.

Cancers that affect the eyeball are called intraocular (within the eye) cancers.

Orbit

The second part of the eye, called the orbit, consists of the tissues surrounding the eyeball. These tissues include muscles that make the globe move in different directions and the nerves attached to the eye.

Cancers of these tissues are called orbital cancers.

Adnexal structures

Finally, there are adnexal (accessory) structures such as the eyelids and tear glands. Cancers that develop in these tissues are called adnexal cancers.