Biomechanical Analysis and Clinical Study of Augmented Versus Conventional Endoscopic Orbital Decompression for Dysthyroid Optic Neuropathy.

Dysthyroid optic neuropathy (DON) represents a severe ocular complication in thyroid eye disease (TED) that can lead to vision loss. Although surgical decompression is a well-established treatment modality, the optimal decompression area remains controversial in orbital decompression surgery. Purpose: This study aims to develop and validate a finite element analysis (FEA) model of DON to compare the biomechanical behavior between patients undergoing conventional or augmented orbital decompression surgery, with potential clinical implications for surgical planning. Methods: FEA models were established using magnetic resonance imaging data from patients with myopathic TED. Pre-disease, preoperative, and postoperative FEA models were developed for both the conventional orbital decompression group and the augmented group, in which the posteromedial floor and the orbital process of the palatine bone were additionally removed to analyze the stress distribution and displacement of the optic nerve, eyeball, and orbital wall. A retrospective analysis was performed to validate the biomechanical analysis results. Results: The FEA results reveal that DON patients experience higher stress on the optic nerve, eyeball, and orbital wall than healthy individuals, mainly concentrated at the orbital apex. Postoperatively, the stress on the optic nerve was significantly reduced in both groups. In addition, postoperative stress on the optic nerve was significantly lower in the augmented group than in the conventional group. The clinical results demonstrate that patients in the augmented group experienced significantly faster and more pronounced improvements in visual acuity and visual field. Conclusions: FEA shows that augmented orbital decompression surgery can alleviate stress more effectively, especially for the optic nerve, which was validated by clinical analysis. This developed FEA model of DON may facilitate determining the appropriate surgical procedure for orbital decompression.