When healthy cells in your eye change or mutate and grow too quickly in a disorganised way, they can form a mass of tissue called a tumour. If these problem cells start in your eye, it is called intraocular cancer, or primary eye cancer. If they spread to your eye from another part of your body, it is called secondary eye cancer.
The most common sign of eye cancer is a change in your vision. You may not be able to see well, or you might see flashes of light or spots (floaters). You also may notice a new dark spot in one eye or a change in its size or shape. But eye cancer does not always cause symptoms early on, and these things can happen for many other reasons.
This is the most common kind of primary eye cancer. It happens when cells form a tumour in a part of your eye called the uvea. It has three parts: the colored part of your eye called the iris, the ciliary body (it makes fluid and helps you focus), and the choroid layer that supplies blood to your eye. This layer is where the cells usually start to change and become cancerous.
This is the most common type of eye cancer in children. It is usually found before age 5. It starts while a baby is in the womb, in the very back part of the eye called the retina. As the baby grows, cells called retinoblasts grow out of control and form a tumour. Sometimes it is first noticed in a picture, when one of the pupils looks different from the other.
This type of skin cancer shows up on or inside your eyelid. The most common form of it — called basal cell carcinoma — happens on your lower lid and is caused by spending too much time in the sun. People who have fair or pale skin are more likely to have it. Eyelid cancer can usually be treated if it is found early.
Secondary eye cancer
In most cases, cancer does not start in the eye, it spreads there from somewhere else in your body. That is called secondary cancer, and it happens most often with breast cancer in women and lung cancer in men.
If the tumour is small and not growing fast and is not causing many problems for you, your doctor may just watch it closely. If it gets larger than 10 millimeters around or 3 millimeters tall or starts to spread, s/he may recommend surgery to take out part or all of the eye, depending on how much of it is affected by the tumour.
After surgery, your doctor may use high beams of energy (usually a type of X-ray) to kill any cancer cells that may still be there. But this can damage healthy cells, too, and that can make your eyes dry, your eyelashes fall out, or cloud your vision.
Treatment: Laser therapy
The most common kind of laser treatment, called transpupillary thermotherapy (TTT), focuses a narrow, intense beam of infrared light on your eye to shrink a small tumour. It is used to treat eye melanoma, because those cells absorb the light energy from the laser. It doesn’t work with intraocular lymphoma. Laser therapy usually causes fewer side effects than surgery or radiation.