malignant melanoma of the choroid
Last reviewed 01/2018
These are primarily choroidal (85%) but may also affect the ciliary body (9%) and the iris (6%). The tumour is invariably unilateral.
Choroidal melanomas usually present with visual field loss or a loss of acuity if the macula is affected. Sometimes they may be discovered incidentally on examination. In time, the tumour infiltrates through Bruch's membrane and pushes the retina forward causing a retinal detachment. Untreated, this results in glaucoma and extension of the tumour, either through the sclera, or outside. Metastases are blood borne and most commonly affect the liver.
Iris tumours usually present with colour change of the iris or a deformity of pupil.
Fluorescein angiography may be helpful in establishing the diagnosis.
Choroidal melanomas may be treated by enucleation or for smaller tumours, by radiotherapy. The prognosis is excellent if the tumour is less than 10 mm diameter.
Iridectomy is advised for iris tumours which have invaded the iris root. Their prognosis is good, and the mortality rate is less than 1%.