Associations between Orbital Morphology and Exophthalmos Changes after Endoscopic Orbital Decompression to Treat Thyroid-related Orbitopathy

Purpose: To investigate orbital morphology parameters associated with exophthalmos changes in patients undergoing endoscopic orbital decompression to treat thyroid-related orbitopathy.Methods: In total, 33 eyes of 18 patients with thyroid-related orbitopathy who underwent endoscopic orbital decompression were included in this retrospective study. Data were collected before and 6 months after surgery. We performed Hertel exophthalmometry and derived orbital morphology parameters from two-dimensional facial computed tomography records. Parameters associated with exophthalmos reduction on univariate linear regression analysis were subjected to multivariate linear regression analyses.Results: Univariate linear regression showed that the preoperative length of the medial orbital wall (β = 0.179, p = 0.032) and the postoperative distance from the cone apex to the medial wall defect (β = -0.139, p = 0.006) were associated with exophthalmos reduction after endoscopic orbital decompression surgery. Multivariate linear regression of these two parameters showed that the distance from the apex to the medial wall defect was associated with exophthalmos reduction (β = -0.118, p = 0.019).Conclusions: The postoperative distance from the cone apex to the medial wall defect was associated with exophthalmos reduction. In patients with thyroid-related orbitopathy, this association should be considered when planning endoscopic orbital decompression.