Postoperative changes of intermittent exotropia type as classified by 1-hour monocular occlusion

Seok Hyun Bae, Young Bok Lee, Soolienah Rhiu, Joo Yeon Lee, Mi Young Choi, Hae Jung Paik, Key Hwan Lim, Dong Gyu Choi

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2 Scopus citations


Purpose To evaluate postoperative changes of the intermittent exotropia type as classified by 1-hour monocular occlusion test. Design Institutional, retrospective study. Methods We retrospectively reviewed the medical records of 179 patients who had undergone surgery for intermittent exotropia with a postoperative follow-up of 6 months or more. We evaluated the exodeviation obtained before and after 1-hour monocular occlusion preoperatively and again at postoperative 1, 3 and 6 months. Intermittent exotropia was divided into 4 types according to Burian’s classification. The main outcome measure was the distribution of intermittent exotropia type based on 1-hour monocular occlusion in both pre- and postoperative periods. Results Of the 179 patients, 152 (84.9%) were assigned preoperatively to the basic type, 14 (7.8%) to the pseudo-divergence excess type, and 13 (7.8%) to the convergence insufficiency type. At postoperative 1, 3, and 6 months, the exotropia-type distribution was shifted predominantly to the basic type (p<0.001, p = 0.004, p = 0.029, respectively). Among the preoperative basic-type patients, 96.9% maintained that type postoperatively. However, only 18.2 and 11.1% of the pseudo-divergence excess and convergence insufficiency types maintained the same type. The proportions of the basic type had increased at postoperative 6 months, from 87.8 to 95.7% for bilateral lateral rectus (BLR) recession, from 73.7 to 92.3% for unilateral recess-resect (R&R), and from 88.0 to 95.0% for unilateral lateral rectus (ULR) recession. Conclusion The type of intermittent exotropia changed mostly to the basic type postoperatively even as classified after 1-hour monocular occlusion. This finding was consistent regardless of the surgical methods (BLR, ULR recession and R&R).

Original languageEnglish
Article numbere0200592
JournalPLoS ONE
Issue number8
StatePublished - Aug 2018

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© 2018 Bae et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


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