Abstract: Objective To summarize the clinical features of patients with IgG4-related diseases （IgG4-RD）with oculomotor impairment as first sign. Design Retrospective case series. Participants From December 2020 to December 2021, 8 IgG4-RD patients with oculomotor impairment as first sign were collected in Beijing Tongren Hospital. Method The medical record data of all patients were reviewed, including primary eye position，the directions of oculomotor impairment, serum IgG4 level, abnormal extraocular muscles according to orbital MRI and treatment methods. Pathological examination results were also reviewed from orbital masses, sinus mucosa or thymus tissue. Main Outcome Measures Clinical features, abnormal extraocular muscles according to orbital MRI, pathological results. Results All 8 patients (100%) presented with oculomotor impairment, including abduction impairment 87.5%, upgaze impairment 75.0%, downgaze impairment and addcution impairment 37.5% respectively. The other main clinical manifestations were visual declines (62.5%) and headaches (37.5%). According to orbital MRI, the local supraocular muscles and lateral rectus muscle thickened with enhancement in 2 patients (25.0%), the local supraocular muscles and lateral rectus muscle were oppressed in 2 patients (25.0%), the diffused extraocular muscles thickened with enhancement in 3 patients (37.5%), extraocular muscles were normal but meningeal thickened with enhancement in 1 patient (12.5%). All patients were accompanied with other part involvements besides nervous system, including lacrimal gland enlargements (62.5%), paranasal mucosa hypertrophies (50.0%) and lymph node reactive hyperplasia (50.0%). All biopsy specimens from orbital masses, nasal mucosae or thymus tissue revealed a large number of IgG4 positive plasma cells with tissue fibrosis or obliterans phlebitis. Conclusion Hypotropia and esotropia in primary eye position and abduction impairment and upgaze impairment are the most common clinical features of IgG4-RD with oculomotor impairment as the first sign. The supraocular muscles and the lateral rectus muscle usually thickened or were oppressed with enhancement in imaging examination. （Ophthalmol CHN, 2022, 31: 151-156）

Key words: oculomotor impairment, IgG4-related disease, IgG4-related ophthalmic disease, extraocular muscle