Intraoperative Relaxed Muscle Positioning Technique for Strabismus Repair in Thyroid Eye Disease Albert J. Dal Canto, MD, PhD, Sue Crowe, COT, Julian D. Perry, MD, Elias I. Traboulsi, MD Objective: To describe the outcomes of a relaxed muscle technique for treatment of dysthyroid strabismus. Design: Retrospective consecutive case series. Participants: Twenty-four patients with thyroid-related orbitopathy (TRO) underwent strabismus surgery using a novel relaxed muscle technique. Methods: Charts of all patients who underwent rectus muscle recession surgery using a relaxed muscle technique between 1997 and 2004 were reviewed. Twenty-four of 28 patients had more than 2 months of follow-up and were included. The extent of recession was determined by marking where the tendon naturally fell while the relaxed muscle rested freely on the globe with the eye in the primary position. The muscle was sutured to the globe at the mark. Linear regression was used to determine the correlation between the degree of strabismus and the amount of recession required to eliminate diplopia. Main Outcome Measures: Surgical outcomes were analyzed 2 months, 6 months, and 1 year after strabismus repair. Excellent success was defined as no diplopia in primary and reading gazes without prisms. Good outcome was defined as no diplopia in primary and reading positions with the use of 10 prism diopters. Poor outcome was defined as persistent diplopia in primary or reading positions despite prisms, or the inability of the patient to tolerate the necessary prisms. Results: Twenty-four patients underwent 60 muscle recessions. Nine had diplopia without a history of orbital decompression, 8 had diplopia before decompression, and 7 developed diplopia only after orbital decompres- sion. Twenty-one patients (87.5%) had an excellent final outcome. A clinically acceptable (excellent or good) final outcome was achieved in 24 of 24 patients (100%) after an average of 1.08 surgeries. All 7 patients who developed diplopia only after decompression had an excellent outcome. Linear regression did not show good correlation between the degree of strabismus and the amount of recession required to eliminate diplopia (maximum R 2 = 0.7292). There were no complications. Conclusions: The relaxed muscle technique provides excellent ocular alignment and relief from diplopia in a majority of patients with TRO-associated strabismus. Patients who develop diplopia only after orbital decom- pression may have a higher success rate. Ophthalmology 2006;113:2324 –2330 © 2006 by the American Academy of Ophthalmology. Thyroid-related orbitopathy (TRO) often produces restric- tive strabismus and diplopia from inflammation and fibrosis of the muscles. The disease most commonly involves the inferior and medial recti to cause hypotropia and esotropia, respectively. Bilateral involvement may result in limited upgaze with or without diplopia secondary to inferior rectus restriction. Approximately 4% to 7% of patients with TRO may require surgical intervention to correct strabismus, 1,2 and 10% to 70% of patients require strabismus surgery after orbital decompression. 3–5 The inflammation-induced fibrosis and thickened ex- traocular muscles limit the predictability of strabismus sur- gery. Successful fusion in primary and reading positions, even with additional prisms, varies from 38% to 80% using fixed sutures 6,7 and from 47% to 81% using adjustable sutures. 1,6,8,9 Despite the use of adjustable sutures, 8% to 27% of patients may require 2 surgeries to eliminate diplopia, even with the use of prisms. 1,6,8,9 We sought to determine the efficacy of our technique for determining the extent of muscle recession. The present technique was inspired by Dr Marshall Parks’ general ap- proach to the handling of restrictive strabismus without the use of an adjustable technique. The authors are not aware of an article by Dr Parks on this technique, but the senior author (EIT) clearly recollects this approach in restrictive strabismus during his training with Dr Parks. This is the technique that the senior author always has used. The fix- ation point for muscle recession is determined intraopera- tively after disinsertion by resting the relaxed muscle on the globe in the primary position. It does not depend on preop- erative deviation measurements or adjustable sutures. Originally received: July 15, 2005. Accepted: April 26, 2006. Manuscript no. 2005-657. From Division of Ophthalmology, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, Ohio. Correspondence to Elias I. Traboulsi, MD, Division of Ophthalmology, Cole Eye Institute, Desk I-32, Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, OH 44195. E-mail: traboue@ccf.org. 2324 © 2006 by the American Academy of Ophthalmology ISSN 0161-6420/06/$–see front matter Published by Elsevier Inc. doi:10.1016/j.ophtha.2006.04.036