Intractable glaucoma characteristically occurs due which one of the following?

Iris melanoma usually grows very slowly along the iris surface and may invade the angle and anterior ciliary body -- intractable glaucoma. Iris melanoma makes up about 5% of uveal melanomas. In general, uveal melanomas are three times commoner in patients with blue/grey than brown irides. They are extremely rare in black people and there is no sexual predilection. Conditions associated with or predispose to early onset uveal melanomas are: a. Ocular melanocytosis b. Nevus of Ota c. Dysplastic cutaneous nevi d. Familial melanoma e. Neurofibromatosis--1 Presentation of iris melanoma is in the fifth to sixth decade, a decade earlier than ciliary body and choroidal melanoma, with enlargement of a pre-existing iris lesion. Treatment: 1. Iridectomy for small tumors 2. Iridocyclectomy for tumors invading the angle 3. Radiotherapy for non-resectable tumors 4. Enucleation for diffusely growing tumors