Eye cancer in most adults is a secondary cancer spread from tumors of the breast, lung, kidneys and prostate glands via the bloodstream or the lymphatic system. Yearly eye exams are the best way to screen for eye cancer or Intraocular lymphoma.
Often melanomas of the eye are found during a routine eye exam. When the doctor looks through the pupil at the back of the eye, they may be able to see a dark spot that may indicate an early melanoma. Because they are rare, there is no screening test for them other than routine eye exams. People who find a dark spot on their iris (colored part of the eye) that is enlarging should have a doctor look at it. The first symptom of this disease is usually trouble with vision. Pain is rare. Intraocular lymphoma most often affects both eyes.
Examination of the eye by an ophthalmologist is the most important step in diagnosing melanoma of the eye. The doctor will look for enlarged blood vessels on the outside of the eye, which can indicate a tumor inside the eye. Using an ophthalmoscope, the ophthalmologist can get a very good look inside the eye and detect a tumor or other abnormality. Most of the time, this examination alone can make the diagnosis. To confirm the diagnosis, imaging tests such as ultrasound or angiography may be required. Angiography is a procedure done with a fluorescent dye that is injected into the bloodstream through a vein in the arm and will travel to the veins in the eye for examination. Very rarely will a biopsy also be needed.
As reported by Jen Creer on our sister site, 
