It's not clear what causes eye melanoma, also called ocular melanoma.
Doctors know that eye melanoma occurs when errors develop in the DNA of healthy eye cells. The DNA errors tell the cells to grow and multiply out of control, so the mutated cells go on living when they would normally die. The mutated cells accumulate in the eye and form an eye melanoma.
Where eye melanoma occurs
Eye melanoma most commonly develops in the cells of the uvea, the vascular layer of your eye sandwiched between the retina, the thin layer of tissue that lines the back inner wall of your eyeball, and the white of your eye (sclera).
Eye melanoma can occur in the front part of the uvea (iris and ciliary body) or in the back part of the uvea (choroid layer).
Eye melanoma can also occur on the outermost layer on the front of the eye (conjunctiva), in the socket that surrounds the eyeball and on the eyelid, though these types of eye melanoma are very rare.