Extraocular Muscle Repositioning and Diplopia: Associated with Ophthalmic Plaque Radiation Therapy for Choroidal Melanoma

Abstract

To evaluate extraocular muscle surgery associated with plaque brachytherapy for choroidal melanoma. Single-center retrospective cohort study. Three hundred twenty-nine eyes of 329 consecutive patients with clinically diagnosed choroidal melanoma. Palladium 103 plaque brachytherapy with or without extraocular muscle surgery. Type of muscle surgery required for each tumor location, timing, incidence, and duration of diplopia, as well as treatment. Two hundred fifty-four patients (n = 254/329; 77.2%) required muscle surgery. One hundred seven patients (n = 107/329; 32.5%) required surgery on 2 or more muscles. Of 373 muscles repositioned, the lateral rectus muscle (n = 115/373; 30.8%) and inferior oblique muscle (n = 70/373; 18.7%) were the most common, correlating to intraocular tumor location (P<0.001). Only 6 tumors (n = 6/61; 9.5%) originating from the iris and ciliary body required muscle surgery for plaque placement. Of the 312 patients with a preoperative visual acuity better than 20/400, diplopia was reported at the first postoperative visit by 41 patients (n = 41/312; 13.1%), 2 of whom had not undergone muscle surgery. Diplopia resolved spontaneously within 1 month in 18 patients (n = 18/41; 43.9%), between 1 and 6 months in 12 patients (n = 12/41; 29.3%), and at more than 6 months in 5 patients (n = 5/41; 12.2%). Among the 312 patients, persistent diplopia occurred in 6 patients (1.9%), including 1 who had not undergone muscle surgery. Treatment was declined in 1 patient, 3 patients (n = 3/41; 7.3%) were treated with prisms, and 2 patients (n = 2/41; 4.9%) required surgery. Extraocular muscle surgery frequently is required for plaque brachytherapy. Although transient diplopia occurred in 11.2% of patients, persistent diplopia occurred in only 1.9% of patients and was treatable.