Matched group study of surgical resection versus cobalt-60 plaque radiotherapy for primary choroidal or ciliary body melanoma. We report the results of a nonrandomized, matched-group, survival and visual preservation study of patients with a choroidal or ciliary body melanoma managed by microsurgical resection of the tumor versus cobalt-60 episcleral plaque radiotherapy. Each treatment group consisted of 30 patients. All patients were matched on a case-by-case basis in terms of tumor size (largest linear tumor dimension), location of the anterior tumor margin relative to the ora serrata, location of the posterior tumor margin relative to the equator, and age at the time of treatment. Although the estimated actuarial 5-year survival probability was slightly greater in the resection group (85.2%) than in the cobalt plaque group (81.8%), this difference was neither clinically impressive nor statistically significant. In contrast, there was a substantially higher rate of early posttreatment severe visual loss in the resection group (P = .0008, Mantel-Haenszel test). 