Secondary tumors occur when a cancer that has started in one part of the body spreads to another area. This spreading occurs when cancer cells travel through the blood or lymph systems to the place where the new, or secondary, tumor starts. Sometimes the secondary site is the eye. If the tumor grows at the back of the eye, it can cause the eye to bulge out at the front.

Various changes in eyesight may result, depending on the size and location of the tumor. Radiation therapy is most often the treatment for the eye tumor. This form of treatment is often successful in at least stopping further growth. Even if radiation therapy destroys the tumor completely, damage to vision that has already occurred could be permanent. If radiation therapy is unsuccessful, surgery may be considered.