Factors Associated with Postoperative Strabismus by Endoscopic Orbital Decompression in Patients with Thyroid-associated Ophthalmopathy

ABSTRACT

Purpose@#To identify the factors associated with postoperative strabismus by endoscopic orbital decompression in patients with thyroid-associated ophthalmopathy (TAO). @*Methods@#This study was a retrospective chart review conducted using the data from 35 patients with TAO (13 with postoperative strabismus and 22 with postoperative non-strabismus) who underwent endoscopic orbital decompression. Hertel exophthalmometry, prism strabismus test, and thyroid-related autoantibody test were performed, and extraocular muscle (EOM) area was calculated using orbital computed tomography. @*Results@#Univariate logistic regression analysis showed that all EOM areas were significantly different between the postoperative strabismus group and non-strabismus group (p < 0.05). Multivariate logistic regression analysis including borderline significant (p < 0.1) variables (age and sex) showed that male sex (β = -3.346, p = 0.031) and left lateral rectus area (β = 0.181, p = 0.046) were associated with postoperative strabismus. In the postoperative strabismus group, there were nine patients with horizontal strabismus and four patients with complex strabismus. In the horizontal strabismus group, the angle of strabismus was positively correlated with the left medial rectus (LMR) area (r = 0.749, p = 0.020). In the complex strabismus group, the vertical angle of strabismus was positively correlated with the left inferior rectus (LIR) area (r = 0.949, p = 0.048). @*Conclusions@#Sex and lateral rectus muscle area were associated with postoperative strabismus by endoscopic orbital decompression in patients with TAO. The areas of LMR and LIR, in particular, were positively correlated with horizontal and vertical angles, respectively. These results could be considered predictive of strabismus after endoscopic orbital decompression.