Melanoma is a type of cancer that usually affects the skin, but it can also start in the eyes. External ocular melanoma occurs in the eyelid, conjunctiva (membrane covering the surface of the eye and insides of the eyelids), or orbit (tissue between eye and bone). Internal ocular melanoma occurs in the uvea, which is the internal structure of the eye consisting of the iris, choroid, and ciliary body. The uveal variety is the most common.
Exposure to ultraviolet light is a risk factor for external ocular melanoma. The closer to the equator, the higher the prevalence of this type of cancer, in a trend very similar to that for skin melanoma. However, the more common uveal melanoma has the opposite geographic distribution. Reference 2 reports that sun radiation appears to have a protective effect for internal malignant tumors in general.
Ocular melanoma metastasizes to the liver in up to 95 percent of patients. About half of these patients also have metastases to the lungs, bone, skin, and brain. The five-year survival rate has been reported to be 50 to 81 percent, depending on the size of the initial tumor. Skin melanoma can also spread to the eyes. One article reports that a patient developed an ocular melanoma 13 years after a skin melanoma was removed, and laboratory analysis showed that the eye cancer was a metastasis of the original skin cancer.
The Ocular Melanoma Foundation supports research and education to help patients and their families. This organization offers an interactive social network with over 900 members. More information is available online at http://www.ocularmelanoma.org/. The website reports, “Metastatic disease is universally fatal.” Thus, early detection by an optometrist or ophthalmologist is extremely important. People with fair skin and blue eyes are at highest risk, but anyone can develop this cancer.
Treatment by radiation, surgery, and chemotherapy can be highly effective if ocular melanoma is diagnosed early.
Shields CL et al, “Ocular melanoma: relatively rare but requiring respect”, Clin Dermatol. 2009 Jan-Feb; 27(1): 122-23.