The uvea is the pigmented middle layer of three concentric layers which form the eyeball.
The uvea encompasses three main parts:
- The iris, as coloured part of the eye, surrounds the pupil.
- The choroid, which is a thin pigmented layer that covers the eyeball. It provides the front of the eye and the retina with blood.
- The ciliary body that comprises the muscles inside the eye, which change the shape of the lens in order to enable the eye to focus on near or distant objects. Additionally, the ciliary body contains cells, which produce a clear fluid between the cornea and the lens.
Melanoma matures from pigment-producing cells called melanocytes and characteristically occur in the skin, but may rarely occur in the mouth, intestines, or eye. 79-81% of ocular melanomas (melanomas of the eye) develop in the uvea. Uveal melanomas represent 3-5% of all melanomas.
Uveal melanomas that start in the iris are the easiest to discover. At the beginning they often appear as a dark spot on the iris, which is benign for many years. Then it begins to grow slowly, developing into melanoma. These melanomas rarely spread to other parts of the body. This is why people with iris melanomas generally have a good prognosis.
The incidence of uveal melanoma in Europe follows a gradient from the north to the south: 2 to 8 new cases per one million population, annually. In the USA 5/million population are affected by uveal melanoma annually.
The particular cause of ocular melanomas is not known. According to scientists, the disease might be related to some conditions, which are called risk factors.
- Uveal melanoma is predominantly determined in Caucasians.
- Eye colour
- People with light-coloured eyes have an increased likelihood to develop melanoma of the eye compared to people with brown eyes.
- Age and gender
- Uveal melanomas can arise at any age. The risk increases with the age.
- The disease is more common in men as in women.
- Inherited conditions
- Individuals with dysplastic nevus syndrome (having many abnormal moles on the skin) have an increased risk for melanoma of the skin and for melanoma of the eye.
- Individuals with oculodermal melanocytosis (abnormal brown spots on the uvea) have an increased risk of developing eye melanoma.
- BAP1 cancer syndrome (a rare inherited condition) leads to an increased risk of for eye melanoma, as well as for some other cancers.
- Unproven risk factors
- Sun exposure: Increased exposure to sunlight or sunlamps emitting UV-B and/or UV-A, a well-recognised risk factor for melanoma of the skin, has been suggested to be a risk factor for melanoma of the eye, but it not has been proven yet.
- Certain occupations: Observation studies have proposed that welders, farmers, fishermen, chemical workers, and laundry workers might have a higher risk of uveal melanoma. Nevertheless, no conclusive links have been found.
Depending on the type and stage of the eye cancer and other factors, the treatment choices may include:
- Radiation therapy
- Laser therapy
- Targeted therapy
It is possible that more than one of type of treatment is used. The best treatment plan is adapted to the patient considering important factors like the location and stage of the cancer, the overall health of the individual, and the chances of curing the disease.
Targeted prevention of uveal melanoma is currently not possible, since the causes are not known yet.
Wearing UV-protected sunglasses when outside in sunlight is recommended by The American Cancer Society. The best protection for the eyes and the surrounding skin is given by wrap-around sunglasses with 99% to 100% UVA and UVB absorption. This precaution might reduce the risk of developing melanoma of the eye and skin.
- German Cancer Society
- Kaliki S, Shields CL, Shields JA. (2015) Uveal melanoma: estimating prognosis. Indian J Ophthalmol. 2015 Feb; 63(2):93-102. doi: 10.4103/0301-4738.154367. Review.
- The Macula Center
- Cancer Wall