Eye Melanoma: Diagnosis

Approved by the Cancer.Net Editorial Board, 01/2023

ON THIS PAGE: You will find a list of common tests, procedures, and scans that doctors use to find the cause of a medical problem. Use the menu to see other pages.

Doctors use many tests to find, or diagnose, cancer. They also do tests to learn if cancer has spread to another part of the body from where it started. If the cancer has spread, it is called metastasis. Doctors may also do tests to learn which treatments could work best.

For most types of cancer, a biopsy is the only sure way for the doctor to know if an area of the body has cancer. In a biopsy, the doctor takes a small sample of tissue for testing in a laboratory. However, a biopsy is not required to confirm the diagnosis of uveal melanoma before treatment. It can often be diagnosed instead through an eye examination or imaging tests. Clinical examination by an ocular oncologist is the gold standard to diagnose and plan treatment for eye melanoma. The doctor may recommend biopsy in rare cases where the diagnosis is uncertain. More commonly, the doctor may recommend biopsy at the time of treatment to obtain tissue for prognostic genetic testing, which is the standard of care according to the National Comprehensive Cancer Network’s guidelines on uveal melanoma. Please note that this link will take you to another, independent website.

How eye melanoma is diagnosed

There are many tests used for diagnosing eye melanoma. Not all tests described here will be used for every person. Your doctor may consider these factors when choosing a diagnostic test:

  • The type of cancer suspected

  • Your signs and symptoms

  • Your age and general health

  • The results of earlier medical tests

In addition to a physical examination, the following tests may be used to diagnose eye melanoma:

Dilated eye examination

Most eye melanoma is found during a routine dilated eye examination before symptoms appear. During the exam, the doctor will dilate, or widen, the pupil with eye drops. This allows them to carefully examine the eye, including the retina and optic nerve. The doctor will view the eye with a lighted instrument called an ophthalmoscope. They may also use a slit lamp, which is a microscope with a light attached to it. A special lens may be placed on the eye to look at the eye’s drainage system. This test is called a gonioscopy.

Imaging tests

Imaging tests show pictures of the inside of the body. They can show if cancer has spread.

In-office tests

  • Fundus photography: Using special cameras, the eye lesion is photographed to allow for careful documentation of the lesion, its borders, and how close it is to important vision structures. The pictures allow for detailed follow-up to assess any growth or change in a suspected lesion. They also help the doctor monitor your response to therapy.

  • Optical coherence tomography (OCT). This non-invasive procedure uses light waves to create detailed, cross-section pictures of the retina and choroid. It can be used to image smaller choroidal tumors and to monitor the eye for side effects from treatments.

  • Ultrasound. An ultrasound uses high frequency sound waves to create pictures of the eye and is used to get details of the tumors located in the back of the eye. A small device called a transducer is painlessly placed on the eye surface. Sound waves sent through the transducer bounce back when they reach the eye organs. The transducer turns the sound waves into images. In some cases, a different ultrasound probe is use to get more detailed images of lesions in the front of the eye. This test is called high-resolution ultrasound biomicroscopy.

  • Fluorescein angiography. This procedure takes a picture of the blood vessels in the eye. A fluorescent dye called fluorescein is injected into the arm. The dye moves through the body and into the blood vessels in the back of the eye. The doctor then takes several quick pictures of the eye. It may help the doctor to confirm the ocular tumor, monitor side effects of treatment, and may also be used to rule out eye problems other than cancer. Indocyanine green angiography is a similar test that uses a different dye called indocyanine green.

  • Transillumination. Using a bright light source (similar to a thin flashlight), the bright light is shone onto the side of the eye to help highlight the location of a suspected tumor.

Radiology tests

The tests below are rarely used to diagnose an ocular tumor. Rather, they are used once the melanoma is diagnosed to check for signs of metastatic disease and to follow patients for future metastatic disease.

  • Computed tomography (CT or CAT) scan. A CT scan takes pictures of the inside of the head using x-rays taken from different angles. A computer combines these pictures into a detailed, 3-dimensional image that shows any abnormalities or tumors. A CT scan can be used to measure the tumor’s size. Usually, a special dye called a contrast medium is given before the scan to provide better detail on the image. This dye is typically injected into a patient’s vein. Sometimes, it can also be given as a pill or liquid to swallow.

  • Magnetic resonance imaging (MRI). An MRI uses magnetic fields, not x-rays, to produce detailed images of the inside of the head. MRI can be used to measure the tumor’s size. A special dye called a contrast medium is given before the scan to create a clearer picture. This dye can be injected into a patient’s vein or given as a pill or liquid to swallow.

  • Positron emission tomography (PET) or PET-CT scan. A PET scan is usually combined with a CT scan (see above), called a PET-CT scan. However, you may hear your doctor refer to this procedure just as a PET scan. A PET scan is a way to create pictures of organs and tissues inside the body. A small amount of a radioactive sugar substance is injected into the patient’s body. This sugar substance is taken up by cells that use the most energy. Because cancer tends to use energy actively, it absorbs more of the radioactive substance. However, the amount of radiation in the substance is too low to be harmful. A scanner then detects this substance to produce images of the inside of the body.

Biopsy and tissue testing

  • Biopsy. A biopsy is the removal of a small amount of tissue for examination under a microscope. A pathologist then analyzes the sample(s). A pathologist is a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease.

    Doctors can often diagnose most cases of uveal melanoma without a biopsy. If conjunctival melanoma or orbital melanoma is suspected, a biopsy can make a definitive diagnosis. However, a biopsy may have risk associated with it and cannot be done for all patients.

    There are different ways to collect a tissue sample, including:

    • Fine needle biopsy. A thin needle is used to remove a small sample of cells.

    • Incisional biopsy. Part of the entire suspicious area is removed.

    • Excisional biopsy. The entire suspicious area is removed. This type of biopsy is commonly used to diagnose conjunctival eye melanoma.

  • Genetic tissue testing. Genetic tests can be done on a uveal melanoma tissue sample removed during a biopsy or surgery. These tests can provide information about how likely the cancer is to spread from the eye to other parts of the body. In some situations, an older tissue sample that was previously removed and preserved can be used for testing.

    Genetic tests that may be done on uveal melanoma samples are:

    • Cytogenetic analysis. This test analyzes a cell’s chromosomes, which contain strands of DNA. The number, size, shape, and arrangement of the chromosomes are examined. Alterations in certain chromosomes, including chromosomes 1, 3, 6, and 8, can help predict how likely a uveal tumor is to metastasize. An alteration in chromosome 3 results in metastatic uveal melanoma in most patients. Approximately 50% of people with uveal melanoma will have this alteration.

      In addition, mutations in the BAP1 gene located on chromosome 3 are found in approximately 50% of uveal melanoma tumors. This mutation is associated with a high risk of metastasis. Mutations in other genes associated with uveal cancer, such as the SF3B1, EIF1AX, and PRAME genes, have a better prognosis.

    • Gene expression profiling. This test identifies specific genes, proteins, and other factors unique to the tumor. Sometimes, eye melanomas are categorized into “class 1” or “class 2” tumors. These classes can help determine the risk of the cancer spreading 5 years after diagnosis. Class 1 tumors have a low risk of spreading. Class 2 tumors have a high risk of spreading.

    These tests can help a patient understand their risk for metastasis. They can also influence how closely the person is monitored during and after treatment. Researchers are still working to develop treatments that prevent metastasis from occurring (see the Latest Research section). Before your treatment begins, talk with your doctor about the risks and benefits of having 1 of these tests and what the results could mean for your care. Patients who receive radiation therapy for uveal melanoma (see the Types of Treatment section) are not able to have a biopsy in the future.

    The results of genetic testing may be combined with other factors that inform uveal melanoma prognosis, such as tumor size, tumor location, and the age of the person at diagnosis. Additional information about prognosis for uveal eye melanoma and conjunctival melanoma can be found in the Stages and Grades section.

Tests for metastatic eye melanoma

If eye melanoma is diagnosed, your doctor may recommend tests to see if the disease has spread outside of the eye to other areas of the body.

Spread to the liver is examined by testing the levels of liver enzymes in a person’s blood or through a CT scan, MRI, or an ultrasound of the liver. The doctor may also recommend a chest PET scan or x-ray to check if the cancer has spread to the lung. An x-ray is a way to create a picture of the structures inside of the body using a small amount of radiation. A brain MRI and other tests may also be considered. For people diagnosed with conjunctival melanoma, a PET scan can look for spread to the lymph nodes.

After all diagnostic tests are done, your doctor will review the results with you. If the diagnosis is cancer, these results also help the doctor describe the cancer. This is called staging and grading.

The next section in this guide is Stages and Grades. It explains the system doctors use to describe the extent of the disease. Use the menu to choose a different section to read in this guide.