Ring melanoma--a rare cause of refractory glaucoma.

BACKGROUND: Ring melanoma of the ciliary body and iris is extremely rare and often has adverse histology. This tumour may cause raised intraocular pressure.
METHODS: A review of four cases of ring melanomas with insidious presentations seen in the ocular oncology service over a 12 month period.
RESULTS: All four patients presented with unilateral anterior segment abnormalities and refractory glaucoma. The misdiagnoses of the causes of the glaucoma included angle recession from previous blunt trauma (patient 1); iridocorneal endothelial (ICE) syndrome supported by endothelial specular microscopy (patients 2 and 3); and melanocytoma on ciliary body biopsy (patient 4). Two patients were treated by several cyclodiode ciliary body ablation treatments and the other two underwent trabeculectomies and Molteno tubes. Two of the four patients have since died from their disease.
CONCLUSION: The ophthalmologist should re-evaluate the diagnosis in patients with anterior segment abnormalities and refractory ipsilateral glaucoma. Endothelial specular microscopy and biopsy of the suspicious lesion may give misleading reassurance. The potential presence of an anterior uveal melanoma must always be considered.