Eye melanoma is a form of cancer that develops in the melanocytes or cells that give the eyes their coloring. Most often, eye melanomas will develop in the region of the eye that cannot be seen upon looking into a mirror. Eye melanoma also doesn't cause any early signs or symptoms. Both of these factors make this type of cancer particularly difficult to detect. When symptoms do manifest, they will usually include a growing dark spot on the iris, a change in pupil shape, blurry vision in one eye, peripheral vision loss, and a sensation of specks or flashes in the vision. These changes typically occur quickly once the melanoma has become advanced. A primary concern with eye melanoma is the spread of cancer to other parts of the body.
While most causes of eye melanoma are unknown, numerous factors will put certain individuals at a higher risk of developing it.
Ocular melanocytosis or melanosis oculi is a congenital eye disease where there is an increased number of melanocytes in the iris or the colored region of the eye, the choroid or vascular eye layer, and surrounding areas. It can present itself in several ways including iris heterochromia or different colored eyes, blue or gray discoloration in the sclera or the white outer eyeball layer, and other discolored lesions around the pupil. Essentially, an individual who has ocular melanocytosis has freckles and discolored spots in their eyes due to the abnormal clumping together of melanocytes or pigment-producing cells. Just like discolorations such as freckles or moles on the skin increase the risk of developing skin melanoma, these freckles or discolorations in the eye due to ocular melanocytosis can also increase an individual's risk of developing eye melanoma. In addition, roughly half of all diagnosed skin melanomas are known to originate from existing moles and skin discolorations. Because the mechanism of eye melanoma is similar to that of skin melanoma, it is likely a considerable percentage of eye melanomas also originate from the eye spots that occur in individuals with ocular melanocytosis.
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