[Application of MRI in the etiological diagnosis of special forms of strabismus]

Objective: To explore the imaging features of patients with special forms of strabismus and summarize the subtypes by using MRI imaging techniques. Methods: A retrospective case series study. Among the patients who visited the Beijing Tongren Hospital between 2006 and 2016, 1 113 patients were identified with special forms of strabismus after complete ophthalmic and orthoptic evaluations. These patients were further evaluated using several types of high-resolution MRI techniques of the oculomotor nerves in the brain, the cavernous sinus, and the orbits. Results: Among the 1 113 patients, 818 patients (73.5%) were identified with MRI abnormal conditions, and 295 patients (26.5%) were identified with MRI normal conditions. Nine different disease types were identified in the studied populations, which included 257 patients (23.1%) with congenital cranial dysinnervation disorders, 209 patients (18.8%) with thyroid associated ophthalmopathy, and 169 patients (15.2%) with abnormalities of the extraocular muscles. Other diseases included orbital fractures (3.3%, 37 patients), intraorbital inflammations (2.7%, 30 patients), tumors (2.3%, 26 patients), injuries of medial rectus muscle after endoscopic sinus surgery (1.2%,13 patients), and lesions of cavernous sinus (2.0%, 22 patients). Additional 55 patients (4.9%) were identified with other causes such as high myopia fixed esotropia, and so on. Conclusion: Summarizing the common clinical characteristics and rules with the help of MRI can further clarify the etiology of special forms of strabismus, and accurately guide the diagnosis and treatment of strabismus. (Chin J Ophthalmol, 2019, 55: 361-368).