Melanoma arising from the choroid and ciliary body is the most common primary intraocular cancer. The Collaborative Ocular Melanoma Study (COMS) randomized clinical trial of I-125 brachytherapy versus enucleation for medium-sized choroidal melanoma (2.5-10.0 mm in thickness and ≤ 16 mm in diameter) showed that, for patients who met the eligibility criteria, there was no statistically significant difference in all-cause mortality between I-125 brachytherapy and enucleation 5, 10, and 12 years following treatment. The COMS trial supported the use of globe-conserving I-125 brachytherapy. Following brachytherapy, however, visual acuity in the treated eye generally declined at a rate of approximately 2 lines of visual acuity per year and nearly 45% of patients lost ambulatory vision (≤20/200) in the treated eye by 3 years.