Iris nevi and melanomas are the most common primary tumors of the iris, with an incidence ranging from 50-70% of all iris tumors; of these, 10-24% may be melanomas. Melanomas arise from malignant proliferation of the neuroectodermally derived iris stromal melanocytes, which replaces the normal iris stromal architecture. While melanoma is the most common primary malignancy of the iris, it comprises only 3%-10% of all uveal melanomas.
Eye melanoma may not cause signs and symptoms. When they do occur, signs and symptoms of eye melanoma can include growing dark spot on the iris, sensation of flashing lights, change in the shape of the dark circle (pupil) at the center of your eye, poor or blurry vision in one eye etc.
Most iris melanomas are believed to arise from active growth in preexisting nevi. Epidemiologic studies suggest that sunlight exposure plays a role in their pathogenesis. Chromosomal mutations may be involved.
Clinical and histopathologic studies show that only 13%-25% of all suspected iris melanomas actually meet the criteria for melanomas. Rates of transformation of a suspicious iris nevus to melanoma are reported at 4% in 10 years and 11% by 20 years.