Melanoma of the iris is a rare condition compared to posterior ocular tumors and in this case report we present a 51-year-old female patient with diffuse iris melanoma. Traditional COMS (Collaborative Ocular Melanoma Study) plaques are used at our institution for radiation therapy, so a novel modification of the traditional plaque was required to allow better conformance with placement on the cornea. The usual silastic insert was machined to dimensions in compliance with the cornea, placed without incident, and treatment delivered with excellent patient tolerance of the modified plaque.