Minimization of Extraocular Muscle Damage in Thyroid Eye Disease Patients Following Surgery Based on Computerized Biomechanics

Background To evaluate the risk of general orbital decompression in patients with thyroid eye disease (TED).Methods In this study, we replicated the behavior of intraorbital tissue in patients with TED based on finite element analysis. The orbit and intraorbital tissues of TED patient who underwent orbital decompression were modeled as finite element models. The stress was examined at a specific location of the removed orbital wall of a patient with TED who had undergone orbital decompression, and its variation was investigated and analyzed as a function of the shape and dimension (to be removed).Results In orbital decompression surgery which removes the orbital wall in a rectangular shape, the stress at the orbital wall decreased as the width and depth of the removed orbital wall increased. In addition, the stress of the non-chamfered model (a form of general orbital decompression) was higher than that of the chamfered model. Especially, in the case of orbital decompression, it can be seen that the chamfered model compared to the non-chamfered model have the stress reduction rate from 11.08% to 97.88%.Conclusions It is inferred that if orbital decompression surgery considering the chamfered model is performed on an actual TED patient, it is expected that the damage to the extraocular muscle caused by the removed orbital wall will be reduced.

Relationship between Serum Thyroid-stimulating Hormone Receptor Autoantibodies and Activity and Severity of Thyroid Eye Disease

Purpose: To study the relationship between the levels of serum thyroid-stimulating hormone (TSH)-receptor autoantibodies (TRAbs) and thyroid eye disease (TED) activity and severity scores.Methods: A cross-sectional study was performed. The medical records of 315 patients diagnosed with TED between March 2014 and December 2019 were reviewed. The clinical activity score (CAS) was used to assess TED activity and a modified NOSPECS score was used for severity grading. The serum TRAb level was measured using two assays: a TSHR binding inhibitory immunoglobulin (TBII) assay and thyroid stimulating immunoglobulin (TSI) bioassay.Results: The TBII and TSI assay results were significantly positively correlated with the CAS (R = 0.113 and 0.211, respectively; p < 0.05), modified NOSPECS score (R = 0.173 and 0.316, respectively; p < 0.05), and proptosis (R = 0.136 and 0.167, respectively; p < 0.05). Both assays demonstrated significant differences in the level of TRAb between patients with and without compressive optic neuropathy or corneal epithelial defects.Conclusions: The levels of TRAbs according to both TBII and TSI assays showed significant correlations with clinical signs of corneal involvement, optic neuropathy, and TED activity and severity.