Melanoma is a type of cancer that develops in the cells that produce melanin — the pigment that gives your skin its color. Your eyes also have melanin-producing cells and can develop melanoma. Eye melanoma is also called ocular melanoma.
Most eye melanomas form in the part of the eye you can't see when looking in a mirror. This makes eye melanoma difficult to detect. In addition, eye melanoma typically doesn't cause early signs or symptoms.
Treatment is available for eye melanomas. Treatment for some small eye melanomas may not interfere with your vision. However, treatment for large eye melanomas typically causes some vision loss.
Eye melanoma may not cause signs and symptoms. When they do occur, signs and symptoms of eye melanoma can include:
A sensation of flashes or specks of dust in your vision (floaters)
A growing dark spot on the iris
A change in the shape of the dark circle (pupil) at the center of your eye
Poor or blurry vision in one eye
Loss of peripheral vision
It's not clear what causes eye melanoma. Health care providers 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 middle layer of your eye (uvea). The uvea has three parts and each can be affected by eye melanoma:
The iris, which is the colored part in the front of the eye
The choroid layer, which is the layer of blood vessels and connective tissue between the sclera and the retina at the back of the uvea
The ciliary body, which is in the front of the uvea and secretes the transparent liquid (aqueous humor) into the eye.
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.
Light eye color. People with blue eyes or green eyes have a greater risk of melanoma of the eye.
Being white. White people have a greater risk of eye melanoma than do people of other races.
Age. The risk of eye melanoma increases with age.
Certain inherited skin disorders. A condition called dysplastic nevus syndrome, which causes abnormal moles, may increase your risk of developing melanoma on your skin and in your eye. In addition, people with abnormal skin pigmentation involving the eyelids and adjacent tissues and increased pigmentation on their uvea — known as ocular melanocytosis — also have an increased risk of developing eye melanoma.
Exposure to ultraviolet (UV) light. The role of ultraviolet exposure in eye melanoma is unclear. There's some evidence that exposure to UV light, such as light from the sun or from tanning beds, may increase the risk of eye melanoma.
Certain genetic mutations. Certain genes passed from parents to children may increase the risk of eye melanoma.
Increasing pressure within the eye (glaucoma). A growing eye melanoma may cause glaucoma. Signs and symptoms of glaucoma may include eye pain and redness, as well as blurry vision.
Vision loss. Large eye melanomas often cause vision loss in the affected eye and can cause complications, such as retinal detachment, that also cause vision loss.Small eye melanomas can cause some vision loss if they occur in critical parts of the eye. You may have difficulty seeing in the center of your vision or on the side. Very advanced eye melanomas can cause complete vision loss.
Eye melanoma that spreads beyond the eye. Eye melanoma can spread outside of the eye and to distant areas of the body, including the liver, lungs and bones.
When to see a health care provider
Make an appointment with your health care provider if you have any signs or symptoms that worry you. Sudden changes in your vision signal an emergency, so seek immediate care in those situations.