Analysis of Added Postoperative Diplopia After Transnasal Endoscopic Inferomedial Wall Decompression for Thyroid-Associated Ophthalmopathy

BACKGROUND: The authors retrospectively analyzed the reported rate of added diplopia and associated factors in patients with thyroid-associated ophthalmopathy (TAO) after transnasal endoscopic inferomedial wall decompression, to illuminate the issue and look for ways to improve prognosis. METHODS: Retrospective analysis was done on the medical records of patients with moderate-to-severe TAO between 2023-01 and 2024-01. Under general anesthesia, transnasal endoscopic inferomedial wall decompression was carried out on each subject. Clinical outcomes included postoperative added diplopia (including new-onset and aggravated), strabismus, and alterations in the extraocular muscles. RESULTS: Sixty-five eyes in 65 patients received treatment. Nineteen patients (29.3%) had new-onset horizontal diplopia at 1 month and 10 patients (15.4%) at 6 months postoperatively; 9 patients (13.8%) experienced aggravated horizontal diplopia at 1 month and 6 patients (9.2%) at 6 months (C2=4.947, P <0.05). The average volume of the medial rectus muscle was the only one to increase in the extraocular muscles (F=34.131, P <0.001), and the preoperative medial rectus muscle volume was higher in the added diplopia patients than in the no-added diplopia patients (F=267.405, P <0.001). CONCLUSIONS: Postoperative diplopia (both new-onset and aggravated) increased in TAO with transnasal endoscopic inferomedial wall decompression. Most added diplopia was horizontal and most added strabismus was esotropia. They were closely associated with changes in the medial rectus's thickness, displacement, and structural alterations. The preoperative medial rectus volume is one of the possible markers of further postoperative diplopia.