Intractable secondary glaucoma is seen in –: (A) Diffuse iris melanoma, (B) Nodular iris melanoma, (C) Melanocytic deposits in anterior part of iris, (D) Melanocyte proliferation in posterior uveal tissue
Answer is A. Iris melanomas may be of two types :-

Circumscribed/ Nodular: - It is the most common type which presents as a pigmented spot on the iris. Glaucoma is less common and usually treatable.
Diffuse iris melanoma: - Present as a unilateral dark iris (hyperchromic hetrochromia). The tumor has diffusely infiltration pattern of growth and invades the intertrabecular spaces, and plugs the drainage mechanism. This results in intractable secondary glaucoma.