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Joo Yeon Lee MD, PhD, Dongchul Choi, Hakjun Lee; Surgical Results of Three Horizontal Muscle Surgery in Large-angle Exotropia. Invest. Ophthalmol. Vis. Sci. 2016;57(12):2435.
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There are surgical options for large-angle exotropia including maximal or supramaximal two horizontal muscle surgery and three or four horizontal muscle surgery. However, the optimal surgery to correct large-angle exotropia is still debated, and the amount of surgery also remains unestablished. The aim of this study is to evaluate the surgical results of three horizontal muscle surgery compared to large bilateral lateral rectus (BLR) recessions and to suggest the surgical dosages in three horizontal muscle surgery for primary large-angle exotropia.
The medical records of 52 consecutive patients who underwent surgery for exotropia with angle of deviation larger than 40 prism diopters (PD) between 2005 and 2013 and had a minimum postoperative follow-up of 6 months were retrospectively reviewed. Postoperative angle of deviation and near stereopsis were compared between the patients who underwent three horizontal muscle surgery (group1) and the patients who underwent large BLR recessions (group2).Surgical dosages used in group1 were composed of BLR recessions of 7-11mm and unilateral medial rectus (MR) resection with an assumption of 3 PD of exotropia correction for every millimeter of MR resection. The amount of BLR recessions in group2 was 9-11 mm.
Of 52 patients, 30 belonged to group1 and 22 belonged to group2. Preoperative angle of deviation was 56.93(40-85) PD in group1 and 44.05(40-55) PD in group2 (p=0.000). Preoperative stereopsis was not different between group1 (2352.8sec) and group2(782.6sec). At 1 day after surgery, group1 showed more overcorrection (8.57 PD of esodeviation) compared to group2 (1.23 PD of esodeviation) (p = 0.009). At 1 month after surgery, group1 showed better alignment (1.62 PD of exodeviation) compared to group2 (5.73 PD of exodeviation) (p = 0.020). At 6 and 12 months after surgery, postoperative angle of deviation had no difference between groups. No consecutive esotropia developed in either group. Postoperative stereopsis was not different between group1 (52.8sec) and group2 (336.3sec).
The three horizontal muscle surgery in this study was safe and effective initial procedure in large-angle exotropia. The surgical results were comparable to that of large BLR recessions. It was useful even in exotropia with very large angle of deviation > 55 PD.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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