choroidal melanomas
An ocular melanoma is a primary malignant tumor arising from the melanocytes within the uvea (iris, ciliary body, and choroid), usually from a choroidal pigmented nevus. It often remains asymptomatic for a long time and is frequently diagnosed during an examination done for other reasons. When symptoms occur, it usually presents as blurry vision or progressive and painless visual field abnormalities. Some patients may report floaters or pain (occasionally) if the tumor impinges on the nerves. Ultrasound of the eye is the most sensitive imaging modality to diagnose the lesion, while MRI is used to document any extrascleral extensions for staging and treatment decisions.
Asymptomatic patients with small pigmented lesions (diameter <10 mm, thickness <3 mm) often experience an extended period of slow growth, during which they may be safely observed without treatment. A common protocol is to repeat the examination in 3 months and every 6 months thereafter.
Large (diameter >10 mm, thickness >3 mm) choroidal melanomas or those presenting with associated symptoms (eg, eye pain, visual disturbances) have a worse prognosis than small asymptomatic lesions; patients should be referred for definitive treatment. Most patients with ocular melanoma requiring treatment will benefit from radiotherapy (brachytherapy or external beam radiotherapy), which has been shown to reduce mortality due to metastatic disease.
Enucleation is the preferred treatment when the tumors are very large, have extrascleral extension, or severe associated pain. However, compared to radiotherapy, enucleation has greater functional and psychologic morbidity and no proven survival advantage.
(Choice B) Photocoagulation of ocular melanoma and its surrounding small vessel blood supply has been advocated for small lesions and marginal recurrence following radiotherapy. However, this is inadequate for primary management of large lesions.