Nevus and Melanoma of the Eye
What is a nevus?
A nevus is a patch of pigmented cells in the uveal layer of the eye. It is usually benign and often described as a freckle at the back of the eye.
What is the uvea?
The uvea is the middle layer of the eye, located between the retina and the tough outer layer called the sclera. In the front of the eye, the uveal layer forms the iris, which is the colored part you see.
What is a suspicious nevus?
A suspicious nevus is typically larger than a benign nevus or may appear raised instead of flat. Certain features, such as elevation or pigment changes, can increase the risk of it developing into a melanoma.
How is a suspicious nevus managed?
Photographic and ultrasound measurements are taken initially and repeated at regular intervals. If a nevus shows increased thickness or growth, or develops subretinal fluid or orange pigment, it may indicate transformation into a melanoma.
What is a uveal melanoma?
A uveal melanoma is a tumor that develops within the uveal layer of the eye, either in the iris or the choroid (the back portion under the retina). The section of the uvea between the iris and retina is called the ciliary body, which can also develop melanomas that are harder to detect because they are behind the iris.
How is choroidal melanoma diagnosed?
Melanomas that arise from suspicious nevi are diagnosed through observation of growth and the presence of risk factors. Often, a choroidal or ciliary body melanoma is detected during a routine eye exam. Key indicators include elevation, subretinal fluid, orange pigment, irregular pigmentation, or absence of drusen. Enlarged external blood vessels may also be an early sign.
To confirm the diagnosis, additional tests such as A-scan and B-scan ultrasound are performed to measure the tumor’s size and structure. A fluorescein angiogram evaluates blood flow and rules out other conditions. An ultrasound biomicroscope is used for evaluating ciliary body and iris melanomas. In rare cases, a fine needle biopsy is performed when the diagnosis remains uncertain.
How is it treated?
After a uveal melanoma diagnosis, testing is done to ensure the cancer has not spread to other parts of the body, such as the liver. Common tests include liver function blood tests, chest X-rays, ultrasounds, and PET-CT scans. If metastasis is present, patients are referred to an oncologist for further treatment.
When no spread is detected, the main goal of treatment is to prevent metastasis. Saving life is the first priority, followed by preserving the eye and vision. Small and medium-sized tumors (under 9 mm) are treated with radioactive iodine-125 plaque therapy, performed as an outpatient procedure. The plaque remains for about a week before removal.
Larger tumors (over 10 mm) may require enucleation (removal of the eye) or proton beam radiation, available at specialized centers. Before proton beam treatment, small clips are surgically implanted to help accurately target the tumor.
In some cases, surgical removal of iris melanomas is possible. A fine needle aspiration biopsy (FNAB) is sometimes performed during or before radiation to analyze the tumor’s genetic profile. This helps estimate the likelihood of spread over time, although preventive treatments for high-risk genetic types are still under study.
How is it followed?
After treatment, the eye is checked regularly with ultrasound and photography to monitor tumor regression. The first measurement is usually done six months after radiation since regression is slow and temporary swelling is common. Systemic follow-up for metastasis is done every 4–12 months using blood tests, imaging, and scans. Radiation-related side effects such as retinopathy, optic neuropathy, and eyelash loss may occur. Anti-VEGF injections or laser therapy can help manage these complications.
What other tumors are seen in the back of the eye?
Metastatic tumors from the breast, gastrointestinal tract, or prostate can appear in the eye, sometimes as the first sign of disease recurrence. These are typically treated with systemic therapy, but radiation may be used if necessary. Hemangiomas of the uvea and retina are benign vascular tumors treated with options like laser, cryotherapy, photodynamic therapy, or anti-VEGF injections to preserve vision.