Surgical management of strabismus following choroidal melanoma plaque brachytherapy

Abstract

Purpose To characterize intraoperative findings, surgical approach, and postoperative outcomes in patients undergoing strabismus surgery following plaque brachytherapy for ocular melanoma. Methods The records of all patients who underwent plaque brachytherapy for choroidal melanoma between May 2007 and June 2016 were reviewed retrospectively to identify those who subsequently required strabismus surgery. Results Of the 461 patients who underwent plaque brachytherapy during the study period, 13 (2.8%) met inclusion criteria. Visual acuity of the affected eye was 20/40 or better in 9 patients (69%). Preoperative horizontal deviation ranged from 0Δ to 52Δ; vertical deviation, from 2Δ to 25Δ. At final follow-up mean horizontal deviation ranged from 0 to 4Δ; vertical deviation, from 0Δ to 12Δ. Intraoperatively, all muscles directly adjacent to the treated area appeared macroscopically thicker than normal despite being functionally underacting. Magnetic resonance imaging showed enlarged muscles adjacent to the plaque radiotherapy. Microscopic examination of muscles in 2 patients showed reactive enlargement of the muscle fibers, granulation tissue, and inflammation. Conclusions Persistent strabismus after plaque brachytherapy is rare. Typical findings include enlarged, underacting rectus muscles adjacent to the area of the plaque, restrictive connective tissue, and incomitant strabismus. Previously disinserted muscles may be found in abnormal locations. In this patient cohort scar tissue removal in conjunction with tightening procedures on the muscle adjacent to the plaque combined with recession of the antagonist muscle frequently resulted in good anatomical outcome. [Figure presented]