Whole-orbit-based multiparametric assessment of disease activity of thyroid eye disease on Dixon MRI.

PURPOSE: This study aimed to explore the diagnostic value of whole-orbit-based multiparametric assessment on Dixon MRI for the evaluation of the thyroid eye disease (TED) activity. METHODS: The retrospective study enrolled patients diagnosed as TED and obtained their axial and coronal Dixon MRI scans. Multiparameters were assessed, including water fraction (WF), fat fraction (FF) of extraocular muscles (EOMs), orbital fat (OF), and lacrimal gland (LG). The thickness of OF and herniation of LG were also measured. Univariable and multivariable logistic regression was applied to construct prediction models based on single or multiple structures. Receiver operating characteristic (ROC) curve analysis was also implemented. RESULTS: Univariable logistic analysis revealed significant differences in water fraction (WF) of the superior rectus (P = 0.018), fat fraction (FF) of the medial rectus (P = 0.029), WF of OF (P = 0.004), and herniation of LG (P = 0.012) between the active and inactive TED phases. Multivariable logistic analysis and corresponding receiver operating characteristic curve (ROC) analysis of each structure attained the area under the curve (AUC) values of 0.774, 0.771, and 0.729 for EOMs, OF, and LG, respectively, while the combination of the four imaging parameters generated a final AUC of 0.909. CONCLUSIONS: Dixon MRI may be used for fine multiparametric assessment of multiple orbital structures. The whole-orbit-based model improves the diagnostic performance of TED activity evaluation.

Metastasis of small cell lung cancer to bilateral extraocular muscles: a case report.

BACKGROUND: Orbital metastasis is a possible complication of small cell lung cancer and a pattern of bilateral invasion of the extraocular muscles has rarely been reported in literature. CASE PRESENTATION: A 46-year-old white male with a past medical history of smoking and stage IV small cell lung carcinoma presented with loss of vision and pain in the left eye. Examination revealed bilateral proptosis and left afferent pupillary defect, and visual acuity was hand motion on the left eye and 4/10 on the right eye. An orbital computed tomography scan showed a compression of the left optic nerve between the extraocular muscles at the apex, and a lateral canthotomy was performed for a new-onset compressive optic neuropathy, with residual visual improvement. There was also significant enlargement of the extraocular muscles in the right orbit. The patient was maintained in palliative treatment with both chemotherapy and local medical and surgical (amniotic membrane cover for exposure keratopathy) ophthalmological treatments until he eventually died 5 months after. CONCLUSION: Bilateral metastasis to the extraocular muscles is a very rare manifestation of small cell lung cancer and the palliative treatment in these cases is challenging.

Asymmetric proptosis in thyroid eye disease.

PURPOSE: Patients with thyroid eye disease (TED) can present with asymmetric disease. The purpose of this study was to evaluate the prevalence of asymmetric TED in an Australian cohort and investigate clinical, biochemical, and radiological associations of asymmetric TED. METHODS: This was a retrospective study of patients with TED who underwent Hertel exophthalmometry and orbital computed tomography (CT) scans. Asymmetry was defined as a difference in the globe protrusion of ≥ 3 mm using Hertel exophthalmometry. Data was collected on patient demographics, clinical disease presentation, thyroid function tests and antibody levels. Muscles volumes were determined by manually segmenting the extraocular muscles on CT scans using a commercially available software. RESULTS: 172 orbits from 86 patients were included in the study. 28 (33%) patients had asymmetric TED. No significant differences were observed in age, gender, thyroid hormone status, anti-thyroid peroxidase levels, thyroid stimulating hormone receptor antibodies, disease activity status, or dysthyroid optic neuropathy between the asymmetric and non-asymmetric groups. The extraocular muscle volumes were significantly higher in the asymmetric orbit compared to its contralateral orbit. CONCLUSION: Asymmetric TED is a reasonably common occurrence in the course of TED. It is associated with higher extraocular muscle volumes, suggesting muscle enlargement as one of the underlying contributors to asymmetric proptosis. Thyroid eye disease should be considered in the differential of asymmetric orbital inflammatory disease.

Correlation between extraocular muscle enlargement and thyroid autoantibodies in thyroid eye disease.

PURPOSE: This study aimed to investigate the factors affecting extraocular muscle enlargement in thyroid eye disease (TED). STUDY DESIGN: Retrospective study. METHODS: The thyroid-stimulating hormone (TSH) receptor antibody (TRAb), thyroid-stimulating antibody (TSAb), antithyroid peroxidase antibody (ATPO), and antithyroglobulin antibody (ATG) levels in patients diagnosed with TED who underwent orbital magnetic resonance imaging were assessed. The control group comprised the contralateral eye of patients who underwent orbital magnetic resonance imaging (MRI) for unilateral eyelid tumors or orbital disease. The thickness of the bilateral rectus muscles and superior oblique muscles was measured on orbital MRI. Muscle enlargement was classified as unilateral/bilateral and symmetric/asymmetric. The effects of age, sex, smoking history, TSH, thyroid hormone, and thyroid autoantibodies on the muscle thickness and number of enlarged muscles were assessed by use of simple and multiple regression analyses. RESULTS: The TED and control groups comprised 41 and 44 cases, respectively. The positivity rate of TSAb in patients with TED was 92.7% higher than that of the other autoantibodies. Muscle enlargement was observed in 29 of the 41 cases (70.7%). Older age and higher TSAb levels were identified as significant factors affecting the total muscle thickness and number of enlarged muscles. Bilateral muscle enlargement and asymmetrical muscle enlargement were observed in 17 (58.6%) and 23 (79.3%) of the 29 cases, respectively. The TSAb levels and age had no significant effect on the type of muscle enlargement. CONCLUSIONS: TSAb showed significant associations with extraocular muscle enlargement. Measurement of TSAb, rather than of TRAb, may be more useful for diagnosing extraocular muscle enlargement in patients with TED.

A Case of Superior Oblique Palsy without Brown Syndrome Induced by a Dog Bite.

BACKGROUND Pseudo-Brown syndrome is characterized by dysfunction of the superior oblique tendon-trochlear complex. Canine tooth syndrome, which involves superior oblique palsy with pseudo-Brown syndrome, results from damage to the trochlear and superior oblique tendon from dog bites around the eye. This report describes a variant of canine tooth syndrome without pseudo-Brown syndrome following a dog bite around the left upper eyelid. In this case, magnetic resonance imaging (MRI) facilitated early diagnosis and therapeutic intervention. CASE REPORT A 19-year-old man presented with torsional diplopia following a dog bite around the left upper eyelid and forehead. Five days after the injury, an alternate prism cover test revealed 6 prism diopters (Δ) exotropia and 5Δ left hypertropia. Ocular motility showed no significant limitation in elevation or depression during adduction. MRI performed on the same day showed a high-signal area extending from the superior oblique tendon to the trochlear region and the superior oblique muscle belly of the left eye. A diagnosis of canine tooth syndrome without pseudo-Brown syndrome was made and oral steroids were administered. Ocular alignment did not improve, so left inferior oblique myotomy was performed 7 months after the injury. The patient's cyclovertical diplopia resolved postoperatively. CONCLUSIONS Dog bites around the eye can result in abnormalities of the extraocular muscles. Early MRI may be useful for diagnosis and determining treatment strategies. This report has highlighted the importance of rapid assessment and management of patients with dog bites involving the eye.

Recurrent inferior oblique myositis and its outcomes.

This report presents a unique case of recurrent idiopathic inferior oblique myositis (IOM) with a focus on clinico-radiological characteristics and histological features. A woman in her early 40s presented with a third episode of IOM following a 12-year period of quiescence. The first two episodes were characterised by unilateral IOM with rapid resolution following oral prednisone treatment. MRI revealed anterior focal enlargement of the left inferior oblique muscle with ipsilateral lacrimal gland enlargement. An inferior oblique muscle and lacrimal gland biopsy demonstrated significant inflammatory infiltrate. An intraorbital injection of triamcinolone acetonide was administered with complete resolution of symptoms within 1 week.

Finite element model of ocular adduction with unconstrained globe translation.

Details of the anatomy and behavior of the structures responsible for human eye movements have been extensively elaborated since the first modern biomechanical models were introduced. Based on these findings, a finite element model of human ocular adduction is developed based on connective anatomy and measured optic nerve (ON) properties, as well as active contractility of bilaminar extraocular muscles (EOMs), but incorporating the novel feature that globe translation is not otherwise constrained so that realistic kinematics can be simulated. Anatomy of the hemisymmetric model is defined by magnetic resonance imaging. The globe is modeled as suspended by anatomically realistic connective tissues, orbital fat, and contiguous ON. The model incorporates a material subroutine that implements active EOM contraction based on fiber twitch characteristics. Starting from the initial condition of 26° adduction, the medial rectus (MR) muscle was commanded to contract as the lateral rectus (LR) relaxed. We alternatively modeled absence or presence of orbital fat. During pursuit-like adduction from 26 to 32°, the globe translated 0.52 mm posteriorly and 0.1 mm medially with orbital fat present, but 1.2 mm posteriorly and 0.1 mm medially without fat. Maximum principal strains in the optic disk and peripapillary reached 0.05-0.06, and von-Mises stress 96 kPa. Tension in the MR orbital layer was ~ 24 g-force after 6° adduction, but only ~ 3 gm-f in the whole LR. This physiologically plausible simulation of EOM activation in an anatomically realistic globe suspensory system demonstrates that orbital connective tissues and fat are integral to the biomechanics of adduction, including loading by the ON.

Clinical, Diagnostic, and Treatment Characteristics of Orbital Liposarcoma.

PURPOSE: To clarify the clinical, diagnostic, and treatment characteristics of orbital liposarcoma. DESIGN: Retrospective observational case series. METHODS: A review was performed of electronic medical records, histopathology, radiological images, and follow-up information for 21 patients with orbital liposarcoma. RESULTS: The predominant clinical manifestation of this disease was painless exophthalmos. The most frequently encountered pathological types were well-differentiated and myxoid liposarcoma. Preoperative radiological images from 15 patients showed that orbital liposarcoma initially developed in extraocular muscle in 9 patients. Furthermore, all well-differentiated liposarcomas exhibited the radiographic characteristics of irregular and ill-defined adipose tissue, whereas only 12.5% of myxoid liposarcomas had the imaging characteristics. For the patients who exclusively underwent surgery, all of those with subtotal excisions experienced recurrence, 63.6% of marginal excisions recurred, and 50% of wide excisions resulted in recurrence. However, none of the patients who underwent marginal excisions or wide excisions combined with adjuvant radiotherapy exhibited recurrence. The analysis of magnetic resonance imaging findings in 3 patients who underwent neoadjuvant radiotherapy revealed that the tumor size remained stable in a patient with well-differentiated liposarcoma, whereas another patient with the same type of tumor exhibited a gradual increase in size. Conversely, a patient with myxoid liposarcoma experienced a significant reduction in tumor size following neoadjuvant radiotherapy. CONCLUSION: Orbital liposarcoma demonstrated a propensity for developing in the extraocular muscle. The radiological images of orbital well-differentiated liposarcomas were characterized by irregular and ill-defined adipose tissue. Surgery combined with radiotherapy demonstrated potential in reducing recurrence rates. Notably, orbital myxoid liposarcoma exhibited greater sensitivity to radiotherapy compared to well-differentiated liposarcoma.

A Case of Idiopathic Orbital Inflammation With Elevated Anti-Mumps Immunoglobulin M Antibody.

A 21-year-old female presented with periocular swelling, diplopia, and painful ophthalmoplegia in the OS. Orbital magnetic resonance imaging revealed an enhanced soft tissue mass involving the left medial rectus muscle. Laboratory test results revealed leukocytosis, elevated reactive C-reactive protein, and positive serum levels of anti-mumps immunoglobulin M (IgM) antibody without systemic manifestations of mumps infection. The clinical course was refractory, and the patient showed a poor response to high-dose steroids. An incisional biopsy revealed stromal fibrosis with focal lymphoid aggregates, indicating sclerosing inflammation. Myopathy of the medial rectus progressed to superior, inferior, and lateral recti involvement of the left orbit. Immunosuppressive agents, including steroids, were administered for 22 months after disease onset. The mumps IgM antibody level was positive for over 5 months and became negative upon testing performed 1 year after the first visit.

Understanding Visual Disorders through Correlation of Clinical and Radiologic Findings.

Patients presenting with visual disturbances often require a neuroimaging approach. The spectrum of visual disturbances includes three main categories: vision impairment, ocular motility dysfunction, and abnormal pupillary response. Decreased vision is usually due to an eye abnormality. However, it can also be related to other disorders affecting the visual pathway, from the retina to the occipital lobe. Ocular motility dysfunction may follow disorders of the cranial nerves responsible for eye movements (ie, oculomotor, trochlear, and abducens nerves); may be due to any abnormality that directly affects the extraocular muscles, such as tumor or inflammation; or may result from any orbital disease that can alter the anatomy or function of these muscles, leading to diplopia and strabismus. Given that pupillary response depends on the normal function of the sympathetic and parasympathetic pathways, an abnormality affecting these neuronal systems manifests, respectively, as pupillary miosis or mydriasis, with other related symptoms. In some cases, neuroimaging studies must complement the clinical ophthalmologic examination to better assess the anatomic and pathologic conditions that could explain the symptoms. US has a major role in the assessment of diseases of the eye and anterior orbit. CT is usually the first-line imaging modality because of its attainability, especially in trauma settings. MRI offers further information for inflammatory and tumoral cases. ©RSNA, 2024 Test Your Knowledge questions for this article are available in the supplemental material.

A case of bilateral amyloidosis localized to extraocular muscles mimicking thyroid eye disease.

BACKGROUND: Amyloidosis is a rare condition characterized by the abnormal deposition of amyloid proteins in various tissues and organs. While systemic amyloidosis has been well-documented, amyloid deposition in extraocular muscles is an exceptionally rare occurrence, with only 35 reported cases. This case report sheds light on the importance of considering amyloidosis in the differential diagnosis of patients presenting with proptosis and diplopia, which are often associated with thyroid eye disease. CASE PRESENTATION: A woman in her twenties sought medical attention due to a complaint of diplopia. Her ocular examination revealed almost normal findings except for exotropia and proptosis. Orbital magnetic resonance imaging displayed fusiform enlargement of nearly all eye muscles, a presentation typically observed in thyroid eye disease. However, despite corticosteroid therapy, her symptoms showed no improvement. Given the unusual lack of response to conventional treatment, and inhomogeneous enhancement of the muscle, an extraocular muscle biopsy was conducted. This biopsy yielded a unique finding-amyloid deposition within the muscle tissue. This discovery was particularly intriguing due to the extreme rarity of amyloidosis affecting extraocular muscles, with fewer than three dozen documented cases worldwide. CONCLUSION: This unique case underscores the critical need for a comprehensive approach to diagnosing patients with proptosis and diplopia. While these symptoms are commonly attributed to thyroid eye disease, it is essential to consider alternative diagnoses such as amyloidosis, especially when standard treatments fail to yield results. The discovery of amyloid deposition in the extraocular muscles, although exceedingly rare, emphasizes the significance of a thorough differential diagnosis. In conclusion, this case report highlights the importance of vigilance in clinical practice, encouraging ophthalmologists to explore less common diagnostic possibilities when faced with challenging cases. Further research and clinical investigation are warranted to better understand the mechanisms and potential treatments for amyloidosis affecting the extraocular muscles.

Tendon-Sparing Extraocular Muscle Enlargement Associated With Chronic Inflammatory Demyelinating Polyradiculoneuropathy.

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is an inflammatory, sensorimotor polyneuropathy. It has presented with a variety of orbital and neuro-ophthalmic manifestations, including cranial nerve hypertrophy and a single case of extraocular muscle enlargement. The authors present a second case of tendon-sparing, extraocular muscle enlargement, resulting in new-onset diplopia and strabismus in a teenager with CIDP. The workup ruled out alternative causes of extraocular muscle enlargement, such as hyperthyroidism, inflammation, or malignancy. As with other cases of CIDP, management involved a combination of immunoglobulin therapy and anti-inflammatory medications. The patient experienced resolution of his symptoms, and radiologic improvement was noted in the muscle enlargement. As many CIDP patients have a favorable treatment response and long-term prognosis, awareness of this rare disease with an early and accurate diagnosis is important.

Bacterial pyomyositis of the extraocular muscles: case report and systematic review.

OBJECTIVE: To describe the manifestations and treatment of extraocular muscle (EOM) bacterial pyomyositis. DESIGN: A systematic review following PRISMA guidelines and a case report. METHODS: PubMed and MEDLINE databases were searched for case reports and case series of EOM pyomyositis using the term "extraocular muscle" combined "pyomyositis" and "abscess". Patients were included as bacterial pyomyositis of the EOMs when there was a response to antibiotics alone or if a biopsy was consistent with the diagnosis. Patients were excluded when pyomyositis did not involve the EOMs or when diagnostic tests or treatment were not in keeping with the diagnosis of bacterial pyomyositis. An additional patient with bacterial myositis of the EOMs, treated locally, was added to the cases identified in the systematic review. Cases were grouped for analysis. RESULTS: There are 15 published cases of EOM bacterial pyomyositis including the one reported in this paper. Bacterial pyomyositis of the EOMs typically affects young males and is caused by Staphylococcus species. Most patients present with ophthalmoplegia (12/15; 80%), periocular edema (11/15; 73.3%), decreased vision (9/15; 60%) and proptosis (7/15; 46.7%). Treatment involves antibiotics alone or in combination with surgical drainage. CONCLUSIONS: Bacterial pyomyositis of the EOM presents with the same signs as orbital cellulitis. Radiographic imaging identifies a hypodense lesion with peripheral ring enhancement within the EOM. An approach to cystoid lesions of the EOMs is helpful in reaching the diagnosis. Cases can be resolved with antibiotics aimed at treating Staphylococcus, and surgical drainage may be required.

Extraocular muscle enlargement and proptosis in carotid cavernous fistulas.

PURPOSE: To evaluate the prevalence and pattern of extraocular muscle enlargement and proptosis in patients with carotid cavernous fistulas (CCF). METHODS: We conducted a retrospective study on patients with digital subtraction angiography (DSA) confirmed CCFs with neuroimaging (computed tomography or magnetic resonance imaging) performed prior to the DSA. The maximum extraocular muscle diameters were recorded. Extraocular muscles were considered enlarged if they were greater than two standard deviations above the normal muscle diameters. Proptosis was defined as the distance between the interzygomatic line to the anterior globe of ≥2 mm compared to the contralateral orbit or ≥21 mm. RESULTS: Forty orbits from 20 patients were included. The mean age of participants was 65 ± 15 years and 13 (65%) were female. Thirteen (65%) fistulas were indirect and seven (35%) were direct. There was enlargement of at least one muscle in 11 (27.5%) orbits, and this was not correlated with the type of fistula (direct/indirect). The inferior rectus was most commonly enlarged in seven orbits (17.5%), followed by the medial rectus in five orbits (12.5%). Proptosis was found in 17 (43%) orbits and was more common ipsilateral to the fistula (58% ipsilateral group vs 19% contralateral group, p < .01). CONCLUSION: Extraocular muscle enlargement was observed in over one-fourth of CCFs. When enlarged, the inferior and medial rectus muscles are most commonly involved. These findings may help clinicians and radiologists when evaluating the CT or MRI scans of patients with suspected CCFs.

Progressive external ophthalmoplegia - A case report.

Progressive external ophthalmoplegia is a slowly progressive hereditary mitochondrial myopathy. Most mitochondrial disorders overlap clinically, enzymatically, and genetically. The most common enzyme defect is the combined deficit of complexes I and IV. Progressive external ophthalmoplegia particularly affects the extraocular muscles and is characterised by ophthalmoplegia, and bilateral ptosis. The ptosis and ophthalmoplegia is unresponsive to anticholinergics, with no effective treatment, but corrective surgery for ptosis as a palliative one. In this article, we report a rare case of a 16-year-old female with characterstic histological features consistent with progressive external ophthalmoplegia.

The Immunoarchitecture of Human Extraocular Muscles.

Purpose: The purpose of this study was to describe the immunoarchitecture of normal extraocular muscles (EOMs) in terms of presence, distribution, and organization of various immune cells. Methods: We performed unilateral orbital exenterations in six fresh human cadavers from elderly patients, followed by dissection of the medial, lateral, superior and inferior rectus, superior and inferior oblique, and superior palpebral levator muscle in their entirety. We further cross sectioned each EOM in an anterior, central, and posterior third. After immunohistochemical staining for CD3, CD8, CD20, CD138, CD68, and podoplanin, quantitative analysis was performed. Results: We found all EOMs (rectus, oblique, and levator muscles) to harbor both T- and B-lymphocytes, with a B-lymphocyte dominance and an absence of plasma cells. The highest prevalence of immune cells was seen in the muscle bellies, with, on average, 488 ± 63 CD3+ T-lymphocytes and 44 ± 110 CD20+ B-lymphocytes per mm2, and significant differences from the anterior (T-lymphocytes) and posterior (T- and B-lymphocytes) thirds. T- and B-lymphocytes were primarily organized in hotspots in the vicinity of blood vessels. In addition, a small resident population of macrophages scattered throughout the specimens was detected. No lymphatic vessels were found in any of the EOMs. Conclusions: These findings can serve as a reference dataset in the assessment of EOM biopsies in the diagnostic process of inflammatory orbital and systemic disorders. Moreover, from a regenerative perspective, our results highlight the importance of taking into account the presence of a resident immune cell population when studying the host immune response on transplanted tissues or engineered constructs.

Supraequatorial displacement with lateral rectus myopexy for treatment of myopic sagging/heavy eye.

PURPOSE: To describe the outcome of the patients diagnosed of sagging/heavy eye associated to myopia, that were operated on with the supra-equatorial displacement with LR myopexy. METHODS: A retrospective study of 9 cases between 2017-2023. The following data were analyzed: horizontal and vertical deviation, diplopia, amblyopia, ductions, ocular torsion, sensorial test, macular pathology, and the orbital magnetic resonance. Treatment was considered Successful if the diplopia was improved or eliminated and a final vertical deviation (VD) ≤5 prism diopters (PD). RESULTS: The mean age (SD) was: 62.11 (4.6) years (100% women). A total of 88.88% presented diplopia. The mean preoperative hypotropia was: 11.33 PD (SD 3.16), and the mean final VD 3.44 PD (SD 3.05). After surgery, the hypotropia was overcorrected in one case, under corrected in 5, and orthophoria was achieved in another three. The technique was associated with surgery of another rectus muscle in 4 subjects. The mean follow-up time after surgery was 34 months (SD 34.62). Six of the 9 patients improved with a vertical deviation ≤5 PD. In 3 patients, the diplopia was eliminated, while in 5 it remained intermittent (three with macular pathology). CONCLUSION: Supra-equatorial displacement with LR myopexy for treatment of myopic sagging/heavy eye, is a therapeutic option if hypotropia is less than 12 PD or the Yokoyama technique is not indicated. A good result was obtained in most cases, although diplopia could only be totally suppressed in three, and another five remained intermittent.

Quantitative assessment of extraocular muscles in Graves' ophthalmopathy using T1 mapping.

OBJECTIVE: To evaluate the performance of T1 mapping in the characterization of extraocular muscles (EOMs) of Graves' ophthalmopathy (GO) patients and investigate its feasibility in assessing the response to glucocorticoid therapy in active GO patients. METHODS: A total of 133 participants (78 active GO, 23 inactive GO, 18 Graves' disease (GD) patients, and 14 healthy volunteers) were consecutively enrolled from July 2018 to December 2020. Native T1 (nT1) and postcontrast T1 (cT1) values of EOMs were measured and compared. The variations in T1 mapping metrics of EOMs were compared pre/post glucocorticoid treatment in 23 follow-up active GO patients. Logistic regression analysis and receiver operating characteristic (ROC) curve analysis were performed. RESULTS: The nT1 of EOMs in GO patients was higher than that in GD patients and healthy volunteers. The nT1 of superior rectus (SR) in active GO was higher than that in inactive GO patients, and it could be used as a potential marker of GO activity (OR: 1.003; 95% CI: 1.001, 1.004), with a diagnostic sensitivity of 86.3% and specificity of 43.7%. Meanwhile, the cT1 of SR, inferior rectus (IR), and medial rectus (MR) in inactive GO patients were higher than those in active GO patients. The nT1 of EOMs achieved sufficient diagnostic performance in evaluating the response to glucocorticoid therapy for follow-up active GO patients (AUC, 0.797; sensitivity, 71.9%; specificity, 85.7%). CONCLUSIONS: T1 mapping could quantitatively assess the activity of GO and the response to glucocorticoid therapy in active GO patients and may even potentially reflect the fibrosis of EOMs. CLINICAL RELEVANCE STATEMENT: T1 values can reflect the pathological status of the extraocular muscle. T1 mapping could help to quantitatively assess the clinical activity of GO and the response to glucocorticoid therapy in active GO patients. KEY POINTS: • Graves' ophthalmopathy patients had greater nT1 of extraocular muscles than Graves' disease patients and healthy volunteers, and nT1 of the superior rectus could be a potential marker of Graves' ophthalmopathy activity. • The cT1 of extraocular muscles in inactive Graves' ophthalmopathy patients was higher than that in active Graves' ophthalmopathy patients, and it might be associated with muscle fibrosis. • nT1 of extraocular muscles could offer sufficient diagnostic performance in evaluating the response to glucocorticoid therapy for follow-up active Graves' ophthalmopathy patients.