For more than 100 years, removal of the eye (enucleation) has been the standard treatment for choroidal melanoma. Before the COMS was initiated in 1986, interest in radiation therapy had increased because of the potential for saving the eye and perhaps some vision. However, the merits of radiation with respect to prolonging patient survival were unknown. The best data from nonrandomized studies suggested that there was no difference in length of remaining life between patients treated with radiation and those whose eyes were enucleated. Thus, it was appropriate and necessary to conduct a randomized, controlled clinical trial in which a large number of patients would be followed for many years in order to compare enucleation and radiation with respect to relative success in prolonging survival of choroidal melanoma patients.