Intraocular melanoma: An eye cancer in which the malignant cells arise in the part of the eye called the uvea. The uvea includes the iris (the colored part of the eye), the ciliary body (a muscle in the eye), and the choroid (a layer of tissue in the back of the eye). The uvea contains pigment-producing cells called melanocytes. When these cells become cancerous, the cancer is called a melanoma. Intraocular melanoma occurs most often in people who are middle aged.
Most ocular melanomas are initially completely asymptomatic. However, as the tumor enlarges, it may cause distortion of the pupil (iris melanoma), blurred vision (ciliary body melanoma), or markedly decreased visual acuity due to secondary retinal detachment (choroidal melanoma). Serous detachment of the retina frequently complicates tumor growth. If extensive retinal detachment occurs, secondary angle-closure glaucoma occasionally develops. Intraocular melanoma is usually found during a routine eye examination, when a doctor looks inside the eye with special lights and instruments.
In the past, enucleation (eye removal) was the accepted standard treatment for primary choroidal melanoma, and it remains the most commonly used treatment for large tumors. Due to the effect of enucleation on the appearance of the patient, the diagnostic uncertainty encountered by the ophthalmologist (particularly in the case of smaller tumors), and the potential for tumor spread, alternative treatments, such as radiation therapy (brachytherapy or external-beam, charged-particle radiotherapy), transpupillary thermotherapy, photocoagulation, and cryotherapy have been developed in an attempt to spare the affected eye and possibly retain useful vision.
The chance of recovery (prognosis) depends on the size and cell type of the cancer, where the cancer is in the eye, and whether the cancer has spread. Iris melanomas have the best prognosis, whereas melanomas of the ciliary body have the worst outlook.