Optic nerve dysfunction in thyroid eye disease: CT

Retinal Perfusion Related to Visual Field Within the Same Asymmetric Thyroid-Associated Ophthalmopathy

PURPOSE

To quantify interocular differences in the retinal microvasculature between disparate eyes and explore associations between the retinal microvasculature and visual field abnormalities within the same asymmetric thyroid-associated ophthalmopathy (TAO) patients.

METHODS

Within the same asymmetric TAO eye, the eye with a severer visual field abnormality (based on the mean deviation [MD]) was considered a severe eye, and the fellow eye was considered mild. The densities of radial peripapillary capillary (RPC) and superficial retinal capillary plexuses (SRCP) were determined using optical coherence tomography angiography. Interocular differences in RPC and SRCP densities were analyzed. A generalized estimating equation (GEE) was used to form a predictive model for visual field abnormalities. Pearson's correlation was used to show the correlation between MD and the densities of RPC and SRCP.

RESULTS

In 57 asymmetric TAO patients, the global RPC density in severe eyes was lower than that in mild eyes (P<0.001), but there was no significant difference in SRCP density between the two groups (P=0.114). In a multivariate GEE model with MD as the outcome, MD was associated only with global RPC density (coefficient β=0.327, P<0.001). The global RPC density was correlated with MD (r=0.360, P=0.003) in severe eyes, but not in mild eyes (r=0.179, P=0.092). No significant correlation was observed between global SRCP density and MD in either group (Both P>0.05).

CONCLUSIONS

RPC density decreased significantly and correlated with visual field abnormalities in severe eyes of TAO patients. Alterations in RPC density may contribute to visual field abnormalities in TAO eyes.

Diagnosis of dysthyroid optic neuropathy: combined value of orbital MRI and intracranial visual pathway diffusion kurtosis imaging

OBJECTIVES

To evaluate the combined performance of orbital MRI and intracranial visual pathway diffusion kurtosis imaging (DKI) in diagnosing dysthyroid optic neuropathy (DON).

METHODS

We retrospectively enrolled 61 thyroid-associated ophthalmopathy (TAO) patients, including 25 with DON (40 eyes) and 36 without DON (72 eyes). Orbital MRI-based apical muscle index (MI), diameter index (DI) of the optic nerve (ON), area index (AI) of the ON, apparent diffusion coefficient (ADC) and signal intensity ratio (SIR) of the ON, DKI-based kurtosis fractional anisotropy (KFA) and mean kurtosis (MK) of the optic tract (OT), optic radiation (OR), and Brodmann areas (BAs) 17, 18, and 19 were measured and compared between groups. The diagnostic performances of models were evaluated using receiver operating characteristic curve analyses and compared using the DeLong test.

RESULTS

TAO patients with DON had significantly higher apical MI, apical AI, and SIR of the ON, but significantly lower ADC of the ON than those without DON (p < 0.05). Meanwhile, the DON group exhibited significantly lower KFA across the OT, OR, BA17, BA18, and BA19 and lower MK at the OT and OR than the non-DON group (p < 0.05). The model integrating orbital MRI and intracranial visual pathway DKI parameters performed the best in diagnosing DON (AUC = 0.926), with optimal diagnostic sensitivity (80%) and specificity (94.4%), followed by orbital MRI combination (AUC = 0.890), and then intracranial visual pathway DKI combination (AUC = 0.832).

CONCLUSION

Orbital MRI and intracranial visual pathway DKI can both assist in diagnosing DON. Combining orbital and intracranial imaging parameters could further optimize diagnostic efficiency.

CLINICAL RELEVANCE STATEMENT

The novel finding could bring novel insights into the precise diagnosis and treatment of dysthyroid optic neuropathy, accordingly, contributing to the improvement of the patients' prognosis and quality of life in the future.

KEY POINTS

• Orbital MRI and intracranial visual pathway diffusion kurtosis imaging can both assist in diagnosing dysthyroid optic neuropathy. • Combining orbital MRI and intracranial visual pathway diffusion kurtosis imaging optimized the diagnostic efficiency of dysthyroid optic neuropathy.

Optic nerve compression associated with visual cortex functional alteration in dysthyroid optic neuropathy: A combined orbital and brain imaging study

AIMS

To investigate the alterations of the optic nerve and visual cortex in dysthyroid optic neuropathy (DON), a subgroup of thyroid eye disease (TED).

METHODS

Multiple orbital imaging biomarkers related to optic nerve compression and the amplitude of low-frequency fluctuations (ALFF) of the brain were obtained from 47 patients with DON, 56 TED patients without DON (nDON), and 37 healthy controls (HC). Correlation analyses and diagnostic tests were implemented.

RESULTS

Compared with HC, the nDON group showed alterations in orbital imaging biomarkers related to optic nerve compression in posterior segments, as well as ALFF of the right inferior temporal gyrus and left fusiform gyrus. DON differed from nDON group mainly in the modified muscle index of the posterior segment of optic nerve, and ALFF of orbital part of right superior frontal gyrus, right hippocampus, and right superior temporal gyrus. Orbital and brain imaging biomarkers were significantly correlated with each other. Diagnostic models attained an area under a curve of 0.80 for the detection of DON.

CONCLUSION

The combined orbital and brain imaging study revealed alterations of the visual pathway in patients with TED and DON as well as provided diagnostic value. The initiation of alterations in the visual cortex in TED may precede the onset of DON.

Three-dimensional soft tissue reconstruction and volume measurement used for the diagnosis of dysthyroid optic neuropathy

PURPOSE

Dysthyroid optic neuropathy (DON) leads to vision loss. This study aimed to investigate a new method that can directly evaluate the change in muscle cone inner volume (MCIV) and distinguish DON orbits from non-DONs.

MATERIALS AND METHODS

This study included 54 patients (108 orbits) who were diagnosed with thyroid eye disease and treated at the Beijing Tongren Hospital between December 2019 and September 2021. The extraocular muscle volume (EOMV), orbital fat volume (OFV), and bony orbit volume (BOV) of the patients were measured using three-dimensional reconstruction. MCIV was measured using artificially defined boundaries. The associations between these volumes and clinical indicators were studied, and the diagnostic efficacy of these volumes for DON was described using receiver operating characteristic (ROC) curves.

RESULTS

The ROC curve showed that the area under the curve of MCIV/BOV (%) combined with EOMV/BOV (%) reached 0.862 (p < 0.001), with a sensitivity of 85.7% and a specificity of 76.1%.

CONCLUSION

The combination of MCIV/BOV (%) and EOMV/BOV (%) is a good indicator for the diagnosis of DON, which aids in the early detection and intervention of DON.

Orbital CT scan parameters in dysthyroid optic neuropathy: a systematic review and meta-analysis

PURPOSE

Addressing Dysthyroid Optic Neuropathy (DON) is crucial due to its debilitating impact in thyroid eye disease (TED). Prompt treatment can preserve vision. Despite lacking definitive diagnostic criteria, computed tomography's (CT) parameters are commonly used for diagnosis. However, these parameters exist without consensus on their diagnostic performance.

DESIGN

Systematic review and meta-analysis.

METHODS

We conducted a meta-analysis of studies assessing orbital CT diagnostic performance for DON in adults with TED. We searched various databases including Medline, PubMed, Scopus, and EMBASE, and others electronic databases, until July 2023. Evaluated CT parameters includes Barrett index (BI), fat prolapse via superior-orbital-fissure (SOF), superior-ophthalmic-vein-dilatation (SOVD), and the Nugent score. Diagnostic Test Accuracy analysis (DTA) was performed using R.

RESULTS

A total of 9 articles with documented target parameters, collectively analysed 212 orbits with DON. Nugent score exhibited highest diagnostic ability with a log diagnostic odd ratio (logDOR) of 2.64 (95% CI, 2.02, 3.25). Another significant DON indicator was a BI ≥ 50%, with a logDOR of 1.97 (95% CI, 1.17; 2.77). Conversely, fat prolapse via SOF and SOVD proved less sensitive, with a logDOR of 1.42 and 1.09 respectively. Regarding the SROC curve, Nugent score and the BI have the greatest AUC. Variations in study locale, participant demographics, and measurement methods accounted for heterogeneity in meta-analysis.

CONCLUSIONS

Nugent score and a BI ≥ 50% prove to be significant diagnostic parameters for DON, distinguishing them from fat prolapse via SOF and SOVD. Prioritizing these parameters can lead to prompt treatment and thus enhanced visual outcomes.

PROSPERO REGISTRATION NUMBER

CRD42023446376.

Diagnostic methods for dysthyroid optic neuropathy: A systematic review and analysis

Diagnosis of dysthyroid optic neuropathy (DON) typically relies on a set of diagnostic clinical features, including decreased visual acuity, impaired color vision, presence of relative afferent pupillary defect, optic disc swelling and ancillary tests including visual field (VF), pattern visual evoked potential (pVEP), and apical crowding or optic nerve stretching on neuroimaging. We summarize various diagnostic methods to establish or rule out DON. A total of 95 studies (involving 4619 DON eyes) met the inclusion criteria. All of the studies considered clinical features as evidence of DON, while most of the studies confirmed DON diagnosis by combining clinical features with ancillary tests. Forty studies (42.1%) used at least 2 out of the 3 tests (VF, pVEP and neuroimaging) and 13 studies (13.7%) used all 3 tests to diagnose DON. In 64 % of the published studies regarding DON, the diagnostic methods of DON were not specified. It is important to note the limitations of relying solely on clinical features for diagnosing DON. On the other hand, since some eyes with optic neuropathy can be normal in one ancillary test, but abnormal in another, using more than one ancillary test to aid diagnosis is crucial and should be interpreted in correlation with clinical features. We found that the diagnostic methods of DON in most studies involved using a combination of specific clinical features and at least 2 ancillary tests.

Predictive factors of development of dysthyroid optic neuropathy among individuals with thyroid-eye disease

PURPOSE

Dysthyroid optic neuropathy (DON) is a severe visual loss condition in thyroid eye disease (TED). This study aimed to identify factors affecting moderate-to-severe TED or DON in Thai populations.

METHODS

We retrospectively reviewed the records of 230 TED patients at Rajavithi Hospital between January 1, 2017, and October 31, 2022.

RESULTS

Mild, moderate-to-severe TED, and DON were found in 60.43%, 22.61%, and 16.96% of participants, respectively. Female predominance was noted in all groups. The proportion of older age, hyperthyroidism, current smokers, and type 2 diabetes mellitus (T2DM) participants were significantly higher in the DON group. Multivariable logistic-regression analysis revealed that hyperthyroidism and current smoking significantly increased the risk of developing moderate-to-severe TED (OR = 3.001, p = 0.010, and OR = 4.153, p = 0.015, respectively). Exophthalmos was the strongest predictor (OR = 6.834, p < 0.001). Regarding DON risk factors, older age (≥55 years) had OR = 3.206 (p = 0.003), hyperthyroidism had OR = 3.228 (p = 0.005), and being a current smoker had OR = 3.781 (p = 0.011). T2DM posed the greatest risk of DON development (OR = 4.111, p = 0.004).

CONCLUSIONS

Hyperthyroidism and current smoking are significant risk factors for moderate-to-severe TED and DON. TED patients with diabetes mellitus or older age should be closely monitored and informed about their risk of developing DON.

Efficacy of tocilizumab in patients with moderate-to-severe corticosteroid-resistant thyroid eye disease: a prospective study

PURPOSE

To evaluate the clinical outcomes of intravenous tocilizumab (TCZ) injection in patients with moderate-to-severe active thyroid eye disease (TED).

METHODS

Patients with active and moderate-to-severe TED who did not respond to conventional therapies were treated with TCZ from June 2019 to January 2021. The medical records of the patients were evaluated before the treatment. We analyzed patient demographics, including the duration of Graves' disease and TED, and assessed subjective symptoms, such as diplopia and ocular movement, clinical activity score (CAS), modified NOSPECS score, and exophthalmos before treatment and at 4, 8, 12, and 16 weeks after the first drug injection. Blood tests, including TSH Rc Ab and TS Ab, were performed before treatment and 24 weeks after the first injection. And orbital computed tomography (CT) was performed and Barrett's Index was calculated at baseline and after completion of all injections.

RESULTS

Nineteen completed the scheduled treatment. There were no significant side effects, other than herpes zoster in one case and headache and dermatitis in another. Clinical symptoms before and 16 weeks after the treatment showed mean CAS decreased by 2.4 points, mean modified NOSPECS score decreased by 3.7 points, and mean exophthalmos decreased by 0.4 mm. Diplopia and extraocular muscle limitation improved in ten and remained stationary in five of the 15 patients, who presented with extraocular motility abnormalities. Six of 11 patients who underwent orbit CT showed improvement in muscle size. The mean TSH Rc Ab decreased by 7.5 IU/L and TS-Ab decreased by 162.9%.

CONCLUSION

TCZ can treat active moderate-to-severe TED, showing high drug compliance and reasonable response to inflammation and extraocular motility abnormality.

Magnetic Resonance Imaging in the Management of Thyroid Eye Disease: A Systematic Review

PURPOSE

MRI may potentially detect active thyroid eye disease prior to elevation of clinical activity score. We aimed to systematically review the existing literature pertaining to MRI thyroid eye disease and to assess the role of MRI in the diagnosis of thyroid eye disease.

METHODS

A Population, Intervention, Comparison, Outcome/Preferred Reporting Items for Systematic Reviews and Meta-Analyses selection criteria was applied to identify studies for inclusion published between the years 2000 and 2023.

RESULTS

Twenty-four articles were identified for inclusion in the systematic review. All included studies utilized MRI as the imaging modality. MRI sequences used included T2-weighted imaging in 87.5%, T1-weighted imaging in 54.2%, diffusion-weighted imaging in 20.8%, and short tau inversion recovery in 16.7%. The most common parameters quantified were signal intensity ratio in 10 studies (41.7%) and T2-relaxation time in 8 studies (33.3%). Signal intensity ratio and T2-relaxation time were shown to correlate with clinical activity score and identify the phase of the disease.

CONCLUSIONS

MRI has untapped potential for further elucidating the highly complex biological processes in thyroid eye disease. As we move away from clinical activity score as a predictor of response to biologic therapy, MRI may prove more important than ever in the risk-benefit analysis around the use of immunomodulators.

Extraocular muscle volume index at the orbital apex with optic neuritis: a combined parameter for diagnosis of dysthyroid optic neuropathy

OBJECTIVES

To evaluate the diagnostic performance of the extraocular muscle volume index at the orbital apex (AMI) and the signal intensity ratio (SIR) of the optic nerve in dysthyroid optic neuropathy (DON).

METHODS

Clinical data and magnetic resonance imaging were collected retrospectively from 63 Graves' ophthalmopathy patients, including 24 patients with DON and 39 without DON. The volume of these structures was obtained by reconstructing their orbital fat and extraocular muscles. The SIR of the optic nerve and axial length of eyeball were also measured. The posterior 3/5 of the retrobulbar space volume was used as the orbital apex to compare parameters in patients with or without DON. Area under the receiver operating characteristic curve (AUC) analysis was used to select the morphological and inflammatory parameters with the highest diagnostic value. A logistic regression was performed to identify the risk factors of DON.

RESULTS

One hundred twenty-six orbits (35 with DON and 91 without DON) were analyzed. Most of the parameters in DON patients were significantly higher than in non-DON patients. However, the SIR 3 mm behind the eyeball of the optic nerve and AMI had the highest diagnostic value in these parameters and are independent risk factors of DON by stepwise multivariate logistic regression analysis. Combining AMI and SIR had a higher diagnostic value than a single index.

CONCLUSIONS

Combining AMI with SIR 3 mm behind the eyeball's orbital nerve can be a potential parameter for diagnosing DON.

CLINICAL RELEVANCE STATEMENT

The present study provided a quantitative index based on morphological and signal changes to assess the DON, allowing clinicians and radiologists to monitor DON patients timely.

KEY POINTS

The extraocular muscle volume index at the orbital apex (AMI) has excellent diagnostic performance for dysthyroid optic neuropathy. A signal intensity ratio (SIR) of 3 mm behind the eyeball has a higher AUC compared to other slices. Combining AMI and SIR has a higher diagnostic value than a single index.

Dysthyroid Optic Neuropathy

PURPOSE

Dysthyroid optic neuropathy (DON) is a sight-threatening complication of thyroid eye disease (TED). This review provides an overview of the epidemiology, pathogenesis, diagnosis, and current therapeutic options for DON.

METHODS

A literature review.

RESULTS

DON occurs in about 5% to 8% of TED patients. Compression of the optic nerve at the apex is the most widely accepted pathogenic mechanism. Excessive stretching of the nerve might play a role in a minority of cases. Increasing age, male gender, smoking, and diabetes mellitus have been identified as risk factors. Diagnosis of DON is based on a combination of ≥2 clinical findings, including decreased visual acuity, decreased color vision, relative afferent pupillary defect, visual field defects, or optic disc edema. Orbital imaging supports the diagnosis by confirming apical crowding or optic nerve stretching. DON should be promptly treated with high-dose intravenous glucocorticoids. Decompression surgery should be performed, but the response is incomplete. Radiotherapy might play a role in the prevention of DON development and may delay or avoid the need for surgery. The advent of new biologic-targeted agents provides an exciting new array of therapeutic options, though more research is needed to clarify the role of these medications in the management of DON.

CONCLUSIONS

Even with appropriate management, DON can result in irreversible loss of visual function. Prompt diagnosis and management are pivotal and require a multidisciplinary approach. Methylprednisolone infusions still represent first-line therapy, and surgical decompression is performed in cases of treatment failure. Biologics may play a role in the future.

Alterations in retrobulbar haemodynamics in thyroid eye disease

PURPOSE

To study the orbital perfusion parameters of ophthalmic artery (OA) and central retinal artery (CRA) in inactive TED and the changes following surgical decompression.

METHODS

Non-randomised clinical trial. 24 inactive moderate-to-severe TED orbits of 24 euthyroid cases underwent surgical decompression and examined again at 3 months. The peak systolic velocity (PSV), end-diastolic velocity (EDV), and resistivity index (RI) of OA and CRA were evaluated using colour doppler imaging and normative database was established using 18 healthy controls.

RESULTS

The mean age was 39.38 ± 12.56 years and male: female ratio was 1: 1.18. Intraocular pressure was higher, and CRA-PSV, CRA-RI, OA-PSV, and OA-EDV were lower in TED in comparison to heathy orbits. The CRA-PSV, CRA-EDV, OA-PSV, and OA-EDV negatively correlated with proptosis and duration of thyroid disease. The area under curve of OA-PSV (95% CI:0.964-1.000, p < 0.001) and OA-EDV (95% CI:0.699-0.905, p < 0.001) helped in differentiating TED orbits from HC, and in predicting the severity of disease. Post decompression, CRA-PSV, CRA-EDV, OA-PSV, and OA-EDV improved, with decrease in CRA-RI and OA-RI in both lipogenic and MO.

CONCLUSIONS

The orbital perfusion is reduced in inactive TED. The changes in OA flow velocities can help in differentiating inactive TED from healthy orbits and progression of TED. Sequential orbital CDI of OA and CRA can serve as an objective tool for case selection and monitoring response to surgical decompression.

Thyroid Eye Disease as Initial Manifestation of Graves' Disease Following Viral Vector SARS-CoV-2 Vaccine: Report of a Case and Review of the Literature

COVID-19, a contagious disease caused by the novel coronavirus SARS-CoV-2, emerged in 2019 and quickly became a pandemic, infecting more than 700 million people worldwide. The disease incidence, morbidity and mortality rates have started to decline since the development of effective vaccines against the virus and the widespread immunization of the population. SARS-CoV-2 vaccines are associated with minor local or systemic adverse reactions, while serious adverse effects are rare. Thyroid-related disorders have been reported after vaccination for COVID-19, and Graves' disease (GD) is the second most common amongst them. Thyroid eye disease (TED), an extrathyroidal manifestation of GD, is rarely observed post-COVID-19 vaccination. All TED cases followed mRNA-based vaccinations, but two new onset mild TED cases post-viral vector vaccine (ChAdox1nCoV-19) have also been reported. We report the case of a 63-year-old woman who presented with new onset hyperthyroidism and moderate-to-severe and active TED 10 days after she received the first dose of a viral vector vaccine against SARS-CoV-2. This is the first case of moderate-to-severe TED after such a vaccine. Our patient was initially treated with intravenous glucocorticoids, and subsequently with intravenous rituximab, due to no response. The disease was rendered inactive after rituximab, but constant diplopia persisted, and the patient was referred for rehabilitative surgery.

Neural network application for assessing thyroid-associated orbitopathy activity using orbital computed tomography

This study aimed to propose a neural network (NN)-based method to evaluate thyroid-associated orbitopathy (TAO) patient activity using orbital computed tomography (CT). Orbital CT scans were obtained from 144 active and 288 inactive TAO patients. These CT scans were preprocessed by selecting eleven slices from axial, coronal, and sagittal planes and segmenting the region of interest. We devised an NN employing information extracted from 13 pipelines to assess these slices and clinical patient age and sex data for TAO activity evaluation. The proposed NN's performance in evaluating active and inactive TAO patients achieved a 0.871 area under the receiver operating curve (AUROC), 0.786 sensitivity, and 0.779 specificity values. In contrast, the comparison models CSPDenseNet and ConvNeXt were significantly inferior to the proposed model, with 0.819 (p = 0.029) and 0.774 (p = 0.04) AUROC values, respectively. Ablation studies based on the Sequential Forward Selection algorithm identified vital information for optimal performance and evidenced that NNs performed best with three to five active pipelines. This study establishes a promising TAO activity diagnosing tool with further validation.

Reduced contrast sensitivity function correlated with superficial retinal capillary plexus impairment in early stage of dysthyroid optic neuropathy

BACKGROUND

To assess the accuracy of contrast sensitivity function (CSF) in detecting dysthyroid optic neuropathy (DON) at an early stage in thyroid-associated ophthalmopathy (TAO) patients and to examine potential factors that may be linked to early visual impairments in these individuals.

METHODS

A total of 81 TAO patients (50 non-DON and 31 DON), and 24 control subjects participated in the study. CSF was measured with the quick CSF (qCSF) method. Optical coherence tomography angiography (OCTA) images of the ganglion cell complex layer (GCCL), superficial and deep retinal capillary plexuses (SRCP and DRCP) in a 3 mm diameter area around the macula were evaluated.

RESULTS

Compared with the controls, the area under the log contrast sensitivity function (AULCSF) and SRCP density were significantly reduced in non-DON and DON patients (all P < 0.05). The GCCL thickness of the DON patients was thinner than that of the controls and non-DON patients (all P < 0.05). The AULCSF was significantly correlated with spherical equivalent refractive error, muscle index, SRCP density and GCCL thickness in TAO patients, respectively (all P < 0.05). However, stepwise multi-regression analysis showed that the AULCSF was only significantly correlated with SRCP density (P < 0.001). Receiver operating characteristic curve analysis showed that the AULCSF produced the most accurate discrimination between non-DON and DON patients from the controls (AUC = 0.831, 0.987, respectively; all P < 0.001).

CONCLUSIONS

CSF change in the early stage of DON is related to SRCP density. It can be an early indicator of visual impairments associated with DON in TAO patients.

Graves' Eye Disease: Clinical and Radiological Diagnosis

Graves' disease is an autoimmune disorder in which hyperthyroidism results in various systematic symptoms, with about 30% of patients presenting with Graves' eye disease (GED). The majority of patients with GED develop mild symptoms, including eyelid retraction, exposure of the globe, superior rectus-levator muscle complex inflammation, and fat expansion, leading to exophthalmos. More severe cases can result in extraocular muscle enlargement, restricted ocular movement, eyelid and conjunctival edema, and compression of the optic nerve leading to compressive optic neuropathy (CON). GED severity can be classified using the Clinical Activity Score, European Group on Graves' Orbitopathy scale, NO SPECS Classification system, and VISA system. CT and MRI aid in the diagnosis of GED through the demonstration of orbital pathology. Several recent studies have shown that MRI findings correlate with disease severity and can be used to evaluate CON. Mild cases of GED can be self-limiting, and patients often recover spontaneously within 2-5 years. When medical treatment is required, immunomodulators or radiotherapy can be used to limit immunologic damage. Surgery may be needed to improve patient comfort, preserve the orbit, and prevent vision loss from optic nerve compression or breakdown of the cornea.

Orbital and ocular perfusion in thyroid eye disease

Thyroid eye disease (TED) is characterized by enlargement of extraocular muscles, an increase in retrobulbar fat, orbital fibrosis, and fluctuations in plasma thyroid hormone levels in most patients, often associated with raised autoantibody titers. The occurrence of orbital space conflict compromises the orbital perfusion, unchecked progression of which results in irreversible loss of visual acuity and visual fields. The quantitative assessment of orbital perfusion can be done by measurement of blood flow velocities in the superior ophthalmic vein (SOV), ophthalmic artery (OA), central retinal artery (CRA), and posterior ciliary artery by color Doppler imaging. The retinal and choroidal microvasculature is studied by optical coherence tomography and optical coherence tomography angiography. The orbital and ocular perfusion fluctuates during the course of TED. Orbital congestion is reflected by the reduction or reversal of SOV flow and an increase in subfoveal choroidal thickness. The active phase is characterized by high blood flow velocities of the OA and CRA. The onset of dysthyroid optic neuropathy is associated with reduced arterial perfusion and reduction in parafoveal and peripapillary vascular density. Orbital decompression improves the SOV flow and decreases the resistivity index of CRA. Sequential evaluation of orbital hemodynamic changes can thus supplement the clinical scoring systems for monitoring and planning intervention in TED.

Computed tomography and magnetic resonance imaging of the orbit in the diagnosis and treatment of thyroid-associated orbitopathy - experience from practice. A Review

The purpose is to acquaint readers with the contribution of imaging methods (IMs) of the orbit, specifically computed tomography (CT) and magnetic resonance imaging (MRI), in the diagnosis of thyroid-associated orbitopathy (TAO). Methods: IMs of the orbit are an indispensable accessory in the clinical and laboratory examination of TAO patients. The most frequently used and probably most accessible method is an ultrasound examination of the orbit (US), which, however, has a number of limitations. Other methods are CT and MRI. Based on the published knowledge implemented in our practice and several years of experience with the diagnosis and treatment of TAO patients, we would like to point out the benefits of CT and MRI in the given indications: visualisation of the extraocular muscles, assessment of disease activity, diagnosis of dysthyroid optic neuropathy and differential diagnosis of other pathologies in the orbit. Our recommendation for an ideal MRI protocol for disease activity evaluation is also included.  Conclusion: IMs play an irreplaceable role not only in the early diagnosis of TAO, but also in the monitoring of the disease and the response to the applied treatment. When choosing a suitable IM for this diagnosis, a number of factors must always be taken into account; not only availability, cost and burden for the patient, but especially the sensitivity and specificity of the given method for the diagnosis of TAO.

Dysthyroid optic neuropathy: Demographics, risk factors, investigations, and management outcomes

Purpose

To analyze the clinical presentations, risk factors, and management outcomes in patients presenting with dysthyroid optic neuropathy (DON).

Methods

This is a retrospective, single-center study carried out on consecutive patients presenting with DON over a period of 4 years (2013-2016). The VISA classification was used at the first visit and subsequent follow-ups. The diagnosis was based on optic nerve function tests and imaging features. Demographic profiles, clinical features, risk factors, and management outcomes were analyzed.

Results

Thirty-seven eyes of 26 patients diagnosed with DON were included in the study. A significant male preponderance was noted (20, 76.92%). Twenty patients (76.9%, P = 0.011) had hyperthyroidism, and 15 (57.69%, P = 0.02) were smokers. Decreased visual acuity was noted in 28 eyes (75.6%). Abnormal color vision and relative afferent pupillary defects were seen in 24 (64.86%) eyes, and visual field defects were seen in 30 (81.01%) eyes. The visual evoked potential (VEP) showed a reduced amplitude in 30 (96.77%, P = 0.001) of 31 eyes and delayed latency in 20 (64.51%, P = 0.0289) eyes. Twenty-six (70.27%) patients were treated with intravenous methyl prednisolone (IVMP) alone, whereas 11 (29.72%) needed surgical decompression. The overall best-corrected visual acuity improved by 0.2 l logMARunits. There was no statistically significant difference in outcome between medically and surgically treated groups. Four patients developed recurrent DON, and all of them were diabetics.

Conclusion

Male gender, hyperthyroid state, and smoking are risk factors for developing DON. VEP, apical crowding, and optic nerve compression are sensitive indicators for diagnosing DON. Diabetics may have a more defiant course and are prone to develop recurrent DON.

Radiomics analysis of the optic nerve for detecting dysthyroid optic neuropathy, based on water-fat imaging

Objective

Detecting dysthyroid optic neuropathy (DON) in the early stages is vital for clinical decision-making. The aim of this study was to determine the feasibility of using an optic-nerve-based radiomics nomogram on water-fat imaging for detecting DON.

Methods

This study included 104 orbits (83 in the training cohort) from 59 DON patients and 131 orbits (80 in the training cohort) from 69 thyroid-associated ophthalmopathy (TAO) without DON patients. Radiomic features were extracted from the optic-nerve T2-weighted water-fat images for each patient. Selected radiomics features were retrained to construct the radiomic signature model and calculate the radiomic score (Rad-score). The conventional MRI evaluation model was constructed based on apical crowding sign, optic-nerve stretching sign and muscle index. The radiomics nomogram model combining the Rad-score and conventional MRI evaluation factors was then developed. Predictive performance of the three models was assessed using ROC curves.

Results

Eight radiomics features from water-fat imaging were selected to build the radiomics signature. The radiomics nomogram (based on Rad-score, apical crowding sign and optic-nerve stretching sign) had superior diagnostic performance than did the conventional MRI evaluation model (AUC in the training set: 0.92 vs 0.80, the validation set:0.88 vs 0.75). Decision curve analysis confirmed the clinical usefulness of the radiomics nomogram.

Conclusions

This optic-nerve-based radiomics nomogram showed better diagnostic performance than conventional MRI evaluation for differentiating DON from TAO without DON. The changes of the optic-nerve itself may deserve more consideration in the clinical decision-making process.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13244-022-01292-7.

Selective deficits of S-cone in thyroid-associated ophthalmopathy patients without clinical signs of dysthyroid optic neuropathy

Purpose

We explored whether thyroid-associated ophthalmopathy (TAO) patients without clinical signs of dysthyroid optic neuropathy (DON) would have a selective deficit mediated by S-cone.

Methods

Thirty-two TAO patients without clinical signs of DON (non-DON, 42.03 ± 9.59 years old) and 27 healthy controls (41.46 ± 6.72 years old) participated in this prospective, cross-sectional study. All observers were tested psychophysically after passing color screening tests and a comprehensive ocular examination. Isolated L-, M-, and S-cone contrast thresholds were measured at 0.5 cyc/deg using Gabor patches. We calculated the area under the receiver operating characteristic (ROC) curve to quantify the ability of chromatic contrast sensitivity to detect the early visual function changes in non-DON patients.

Results

S-cone contrast sensitivity in non-DON patients was found to be lower than that of healthy controls (P < 0.001), whereas the sensitivities to L- and M-cone Gabor patches were similar between these two groups (P = 0.297, 0.666, respectively). Our analysis of the ROC curve revealed that the sensitivity to S-cone had the highest index to discriminate non-DON patients from healthy controls (AUC = 0.846, P < 0.001). The deficit of S-cone was significantly correlated with muscle index in non-DON patients (R = 0.576, P = 0.001).

Conclusion

There is a selective S-cone deficit in the early stage of TAO. S-cone contrast sensitivity could serve as a sensitive measure of visual impairments associated with early DON in patients with TAO.

Risk prediction of dysthyroid optic neuropathy based on CT imaging features combined the bony orbit with the soft tissue structures

Purpose

To analyze computed tomographic (CT) imaging features of patients with dysthyroid optic neuropathy (DON) retrospectively and deduce a more appropriate predictive model.

Methods

The CT scans and medical records of 60 patients with clinically proven Graves' ophthalmopathy (GO) with (26 women and 10 men) and without DON (16 women and 8 men) were retrospectively reviewed, and 20 age- and sex-matched control participants (12 women and 8 men) were enrolled consecutively. The bony orbit [orbital rim angle (ORA), medial and lateral orbital wall angles (MWA and LWA), orbital apex angle (OAA), and length of the lateral orbital wall (LWL)], and the soft tissue structures [maximum extraocular muscle diameters (Max EOMD), muscle diameter index (MDI), medial and lateral rectus bulk from inter-zygomatic line (MRIZL and LRIZL), proptosis, intraorbital optic nerve stretching length (IONSL), superior ophthalmic vein diameter (SOVD), apical crowding, and presence of intracranial fat prolapse] were assessed on a clinical workstation. The CT features among groups were compared, and a multivariate logistic regression analysis was performed to evaluate the predictive features of DON.

Results

All bony orbital angle indicators, except ORA (p = 0.461), were statistically different among the three groups (all p < 0.05). The values of MWA, LWA, OAA, and LWL were larger in the orbits with the DON group than in the orbits without the DON group (all p < 0.05). The MDI, MRIZL, proptosis, IONSL, and SOVD were statistically significantly different among the three groups (all p < 0.05), in which the orbits with the DON group were significantly higher than the orbits without the DON group and control group. The apical crowding was more severe in the orbits with the DON group than in the orbits without the DON group (p = 0.000). There were no significant differences in the LRIZL and the presence of intracranial fat prolapse (all p > 0.05). The multivariate regression analysis showed that the MWA, MDI, and SOVD were the independent factors predictive of DON. The sensitivity and specificity for the presence of DON by combining these three indicators were 89 and 83%, respectively.

Conclusion

Bone and soft tissue CT features are useful in the risk prediction of DON, especially the MWA, MDI, and SOVD were the independent factors predictive of DON.

Reduced choroidal peripapillary capillaries in thyroid-associated ophthalmopathy with early stage of dysthyroid optic neuropathy

AIM

To investigate whether the subtle change of choroidal/retinal vessel densities and volumes in thyroid-associated ophthalmopathy (TAO) could be an early sign to detect dysthyroid optic neuropathy (DON).

METHODS

This was a retrospective cross-sectional study, and a total of 98 eyes from 50 subjects were enrolled under certain criteria. Thirty-four eyes of normal controls and 64 eyes of TAO, including 39 eyes of DON and 25 eyes of TAO without DON, underwent optical coherence tomography angiography (OCTA) scanning. All the tested parameters of OCTA scanning including choroid radial peripapillary capillaries (RPC), retinal nerve fiber layer (RNFL), and macular ganglion cell complex (GCC) were compared among groups, and the correlation between OCTA parameters and visual function parameters was also investigated.

RESULTS

Whole choroidal RPC was significantly reduced in DON (48.24%±0.4978%) compared to normal (50.33%±0.3173%) and TAO without DON (49.16%±0.5463%; P=0.0041). The reduction of whole choroidal RPC was also correlated with visual field (VF) defect in DON (r=0.5422, n=39). Although vision acuity and VF were improved in all the patients with DON after being treated with medical and surgical decompression, the reduction of RPC density were not reversed.

CONCLUSION

There is a notable reduction in choroidal RPC in DON, which is correlated with VF defect. The reduction of RPC density could not be reversed immediately by medical and surgical decompression even when vision and VF were improved. These findings suggest that choroidal RPC could be a useful parameter to diagnose and monitor early stage of DON.

Diagnostic Ability of Barrett’s Index and Presence of Intracranial Fat Prolapse in Dysthyroid Optic Neuropathy

Background

Dysthyroid optic neuropathy (DON) is one of the most serious visual loss threats for patients with Graves’ ophthalmopathy (GO). Barrett’s index (BI) and intracranial-fat prolapse have been used in diagnosing DON. However, these parameters are rarely used in Southeast Asian populations with a variety of cut-off values.

Objective

To evaluate the performance of BI and fat prolapse in diagnosing of DON, and to study the correlation between their parametric values with visual acuity (VA) and visual field defect (VF).

Methods

Between January 2011 and December 2020, orbits affected by GO were retrospectively reviewed and classified into 2 groups based on the presence or absence of DON. All orbital-computed-tomography (CT) scans were measured for BI and fat prolapse. Diagnostic performance of BI and fat prolapse was analyzed and evaluated in relation to visual outcome.

Results

We included orbits with DON (23 orbits) and the absence of DON (61 orbits). BI was significantly higher in patients in the DON group (47.68 ± 12.52%) compared to the absence of DON (37.55 ± 10.88%), p < 0.001. The presence of fat prolapse was significantly higher in the DON group (p = 0.003). BI at 40% provided best diagnostic performance with sensitivity of 78.3%/specificity of 63.9%. The presence of fat prolapse 4.5 mm via the superior-ophthalmic-fissure (SOF) had a lower sensitivity compared with fat prolapse 2.5 mm. Comparison between area under the curve (AUC) of BI and fat prolapse revealed no statistically significant difference (AUC 0.742 and 0.705 in BI and fat prolapse, respectively, p = 0.607). A negative correlation between the BI and fat prolapse with VA and VF was observed (p < 0.001).

Conclusion

Measurement of BI is a simple diagnostic method for detecting DON in Thai populations. The presence of fat prolapse (2.5 mm) provides a lower sensitivity compared with a BI at 40%. A slightly larger BI or fat prolapse should be suspected of DON for early treatment.

Increased Orbital Muscle Fraction Diagnosed by Semi-Automatic Volumetry: A Risk Factor for Severe Visual Impairment with Excellent Response to Surgical Decompression in Graves’ Orbitopathy

Graves’ orbitopathy (GO) leads to increased orbital tissue and causes symptoms such as exophthalmos, functional complaints, or dysthyroid optic neuropathy. Different GO types with fat and/or muscle enlargement were identified, and increased muscle appears to particularly influence visual status and treatment response. The current study examines visual parameters dependent on orbital muscle volume fraction in a surgically treated GO cohort. After volumetric analysis of the preoperative orbital content, 83 orbits in 47 patients were categorized into predefined groups (increased or not-increased muscle fraction). All cases underwent pterional orbital decompression, and pre- and postoperative visual status was retrospectively analyzed. Forty-one orbits revealed increased and 42 orbits revealed not-increased muscle volume (mean fraction 29.63% versus (vs.) 15.60%). The preoperative visual acuity (VA) was significantly lower in orbits with increased vs. not-increased muscle volume (mean VA 0.30 vs. 0.53, difference 2.5 lines). After surgery, mean VA improved significantly by 1.7 lines in orbits with increased muscle volume. Not preoperative, but postoperative exophthalmos was significantly lower in orbits with not-increased muscle volume. Increased orbital muscle is associated with significantly reduced VA, but can be remarkably improved by pterional orbital decompression. Therefore, surgical therapy should be considered particularly in decreased VA with orbital muscle enlargement.

Chromatic visual evoked potentials identify optic nerve dysfunction in patients with Graves' orbitopathy

PURPOSE

To explore visual dysfunction in Graves' orbitopathy (GO) objectively by analyzing chromatic visual evoked potentials (cVEP) and evaluate its diagnostic efficiency for dysthyroid optic neuropathy (DON).

METHODS

In this cross-sectional study, we analyzed pattern-reversal VEP (pVEP), red-green (R-G) and blue-yellow (B-Y) cVEP in 93 subjects (21 with DON, Group A, 30 with GO, Group B, and 42 healthy controls, Group C) at Wuhan Union Hospital, China.

RESULTS

Compared with Group C, the amplitudes of B-Y cVEP were significantly lower in Group B, whereas all amplitudes of cVEP, latencies and amplitudes of pVEP in Group A were significantly impaired. In addition, the pVEP latency at 60 arcmin (60'), pVEP amplitudes and R-G cVEP amplitudes were significantly different between Group A and B. Moreover, 60'cVEP R-G negative-positive (N-P) amplitude was correlated with crowding index (P = 0.001), the average thickness of ganglion cell layer and inner plexiform layer (P = 0.004). Furthermore, combination of 60'cVEP R-G amplitude and 60'pVEP P100 latency had better diagnostic efficiency than each single parameter, with optimal cut-off values of 14.20 μV and 110.65 ms, respectively.

CONCLUSION

GO may induce electrophysiological changes. The presence of B-Y cVEP anomalies in moderate to severe GO patients may be an early sign of preclinical DON. A decline in 60'cVEP R-G amplitude is associated with apical crowding and thinner inner intra-retinal layers. The combination of 60'cVEP R-G N-P amplitude and 60'pVEP latency can be a useful diagnostic index for DON.

Multi-Parametric Diffusion Tensor Imaging of The Optic Nerve for Detection of Dysthyroid Optic Neuropathy in Patients With Thyroid-Associated Ophthalmopathy

Objective

To evaluate the microstructural changes of the orbital optic nerve in thyroid-associated ophthalmopathy (TAO) patients with or without dysthyroid optic neuropathy (DON) using diffusion tensor imaging (DTI) and investigate whether DTI can be used to detect DON.

Materials and Methods

59 bilateral TAO patients with (n= 23) and without DON (non-DON, n= 36) who underwent pretreatment DTI were included and 118 orbits were analyzed. The clinical features of all patients were collected. DTI parameters, including mean, axial, and radial diffusivity (MD, AD, and RD, respectively) and fractional anisotropy (FA) of the intra-orbital optic nerve for each orbit were calculated and compared between the DON and non-DON groups. ROC curves were generated to evaluate the diagnostic performance of single or combined DTI parameters. Correlations between DTI parameters and ophthalmological characteristics were analyzed using correlation analysis.

Results

Compared with non-DON, the DON group showed decreased FA and increased MD, RD, and AD (P < 0.01). In the differentiation of DON from non-DON, the MD was optimal individually, and the combination of the four parameters had the best diagnostic performance. There were significant correlations between the optic nerve's four DTI metrics and the visual acuity and clinical active score (P < 0.05). In addition, optic nerve FA was significantly associated with the amplitude of visual evoked potentials (P = 0.022).

Conclusions

DTI is a promising technique in assessing microstructural changes of optic nerve in patients with DON, and it facilitates differentiation of DON from non-DON eyes in patients with TAO.

Imaging of the medial rectus muscle predicts the development of optic neuropathy in thyroid eye disease

Goal of the study was to evaluate bony orbit remodeling and extraocular muscle (EOM) volume in thyroid eye disease (TED) and their role as predicting factors for development of dysthyroid optic neuropathy (DON). Orbital computed tomography of 92 patients with TED with (76 orbits) or without DON (98 orbits) were retrospectively evaluated. Orbits (n = 40) of subjects without TED served as controls. Measurements of the bony orbit as well as EOM volume were incorporated into a generalized linear mixed model to predict DON. The angle of the medial orbital wall was significantly smaller (p < 0.001) in patients with TED (− 2.3 ± 3.6°) compared to patients with TED + DON (1.0 ± 4.1°). Both groups differed significantly from controls (− 4.2 ± 2.7°). Bowing of the medial orbital wall correlated positively with muscle volume (r = 0.564; p < 0.001). Total EOM volume was significantly larger in TED + DON (7.6 ± 2.5cm³) compared to TED only (5.6 ± 3.0cm³; p < 0.001) or controls (2.6 ± 0.5cm³). Multivariate analysis revealed the medial rectus muscle volume (TED: 1.06 ± 0.48cm³ vs. TED + DON: 2.16 ± 0.84cm³) as the strongest predictor, achieving a specifity of 86.7% and a sensitivity of 73.7% in diagnosing DON in univariate analysis. Though characterized by a wide range of variability, increased medial rectus muscle volume is the strongest predictor for DON in our patient cohort with TED when analyzing a single muscle.

Current insights of applying MRI in Graves' ophthalmopathy

Graves' ophthalmopathy (GO) is an autoimmune disease related to Grave's disease (GD). The therapeutic strategies for GO patients are based on precise assessment of the activity and severity of the disease. However, the current assessment systems require development to accommodate updates in treatment protocols. As an important adjunct examination, magnetic resonance imaging (MRI) can help physicians evaluate GO more accurately. With the continuous updating of MRI technology and the deepening understanding of GO, the assessment of this disease by MRI has gone through a stage from qualitative to precise quantification, making it possible for clinicians to monitor the microstructural changes behind the eyeball and better integrate clinical manifestations with pathology. In this review, we use orbital structures as a classification to combine pathological changes with MRI features. We also review some MRI techniques applied to GO clinical practice, such as disease classification and regions of interest selection.

Elevated pulse pressure correlated with reduced retinal peripapillary capillary in thyroid-associated ophthalmology with visual field defect

PURPOSE

To quantify the retinal vessel density in thyroid-associated ophthalmology (TAO) patients with visual field (VF) defect and examine its associations with mechanical and system vascular risk factors for underlying pathogenesis of VF defect in TAO.

METHODS

The cohort was composed of 62 TAO eyes (39 with VF defect and 23 without VF defect). The pulse pressure (PP), intraocular pressure (IOP), ophthalmic rectus muscular index (MI), superficial retinal capillary plexus (SRCP), radial peripapillary capillary (RPC) density, and other related parameters were measured. The associations among these factors and VF mean deviation (MD) were analyzed.

RESULTS

In TAO patients with VF defect, reduced RPC density, higher PP, and larger horizontal and vertical MI were found (all P < 0.03) when compared to TAO patients without VF defect. The RPC density was correlated with VF MD value (r = 0.242, P = 0.029), while SRCP density was not (P = 0.419). In univariable general estimating equation (GEE) analysis with RPC density as the outcome, PP and its fluctuation showed a significant association (both P < 0.04). In the final RPC model with multivariable GEE analysis, only PP (β = -0.082, P = 0.029) showed significance while PP fluctuation (P = 0.080) did not.

CONCLUSIONS

The elevated PP was correlated with reduced retinal peripapillary perfusion in TAO resulting in VF defect. These data suggested that the system vascular factor may be important in the pathogenesis of reduced retinal perfusion resulting in visual impairment in TAO.

Retinal nerve fiber layer and ganglion cell complex thickness as a diagnostic tool in early stage dysthyroid optic neuropathy

PURPOSE

To compare the diagnostic accuracy of peripapillary retinal nerve fiber layer with macular ganglion cell complex thickness as an auxiliary tool for the early diagnosis of dysthyroid optic neuropathy and help assess the effectiveness of the treatment.

METHODS

In this retrospective case-control study, a total of 58 thyroid-associated opthalmopathy patients and 58 healthy participants were enrolled in the study. Thyroid-associated opthalmopathy patients were divided according to the European Group Graves' Orbitopathy severity classification. The thicknesses of peripapillary nerve fiber layer and macular ganglion cell complex were measured using optical coherence tomography and their correlation with the severity of the disease as well as the effect of the treatment was investigated.

RESULTS

No statistically significant differences were found between the mild thyroid-associated opthalmopathy group and the control group in both peripapillary nerve fiber layer and macular ganglion cell complex thickness. In the moderate-to-severe thyroid-associated opthalmopathy group, however, Temporal and Nasal peripapillary nerve fiber layer thicknesses were lower compared to the control group (p = 0.041, p = 0.012), whereas in the sight-threatening thyroid-associated opthalmopathy group Temporal Inferior, Nasal Superior, and mean (G) peripapillary nerve fiber layer thicknesses were larger (p = 0.000, p = 0.004, p = 0.000). No significant differences were observed in the macular ganglion cell complex thickness among the different severity groups and the control groups (p > 0.05). After treatment, the mean peripapillary nerve fiber layer thickness decreased whereas mean macular ganglion cell complex thickness showed no significant change in the sight-threatening group. A correlation was established between exophthalmos, best corrected visual acuity, clinical activity score, disease course, and the mean peripapillary nerve fiber layer thickness. The area under curve analysis indicated that mean peripapillary nerve fiber layer thickness can be used as a powerful diagnostic tool in early stage dysthyroid optic neuropathy in thyroid-associated opthalmopathy patients.

CONCLUSION

Our study indicates that peripapillary nerve fiber layer act as an auxiliary tool for the early diagnosis of dysthyroid optic neuropathy and helps assess the effectiveness of the treatment.

Multiparametric quantitative MRI for the evaluation of dysthyroid optic neuropathy

OBJECTIVE

To evaluate the ability of quantitative MRI parameters for predicting dysthyroid optic neuropathy (DON).

METHODS

We retrospectively collected and analyzed the clinical features and 3.0 T MRI data of 59 patients with Graves orbitopathy (GO), with (n = 26) and without DON (n = 33). We compared MRI quantitative parameters, including the modified muscle index (mMI), proptosis, volume of intra-orbital fat, mean apparent diffusion coefficient value, and T2 value of the optic nerve among patients with and without DON. A logistic regression analysis was performed to identify the risk factors associated with DON. Moreover, we performed a receiver operating characteristic curve analysis and decision curve analysis to evaluate the diagnostic performance of the identified parameters for DON.

RESULTS

We studied 118 orbits (43 and 75 with and without DON, respectively). The mMI and mean T2 value of the optic nerve were significantly greater in orbits with DON (p < 0.001). A greater mMI at 21 mm (odds ratio (OR), 1.039; 95% confidence interval (CI): 1.019, 1.058) and higher mean T2 value of the optic nerve (OR, 1.035; 95% CI: 1.017, 1.054) were associated with a higher risk of DON. A model combining the mMI at 21 mm and mean T2 values for the optic nerve effectively predicted DON in patients with GO, with a sensitivity and specificity of 95.3% and 76%, respectively.

CONCLUSION

A quantitative MRI parameter combining the mMI at 21 mm and mean T2 value of the optic nerve can be an effective imaging marker for identifying DON.

KEY POINTS

• Patients with GO and DON had greater mMI than those without DON. • Optic nerves in patients with DON demonstrated an increased T2 value. • The quantitative MRI parameter combining the mMI at 21 mm and mean T2 value of the optic nerve is the most effective method for diagnosing DON.

Extrathyroidal Manifestations of Thyroid Disease: Graves Eye Disease

Graves disease is an autoimmune disorder caused by the breakdown of immune tolerance to thyroid antigens against the TSH receptor. In approximately 25% of patients, an inflammatory condition, Graves eye disease (GED), affects the orbital soft tissues. About 60% of patients develop mild symptoms including fat expansion and inflammation of the levator muscle complex with resultant proptosis, eyelid retraction, and exposure of the globe. The remaining patients experience enlargement of one or more of the extraocular muscles, leading to conjunctival and eyelid edema and congestion, restricted ocular movement with resultant diplopia, and optic nerve compression leading to compressive optic neuropathy.

Correlation of Automated Computed Tomography Volumetric Analysis Metrics With Motility Disturbances in Thyroid Eye Disease

PURPOSE

The authors sought to examine relationships between CT metrics derived via an automated method and clinical parameters of extraocular muscle changes in thyroid eye disease (TED).

METHODS

CT images of 204 orbits in the setting of TED were analyzed with an automated segmentation tool developed at the institution. Labels were applied to orbital structures of interest on the study images, which were then registered against a previously established atlas of manually indexed orbits derived from 35 healthy individuals. Point-wise correspondences between study and atlas images were then compared via a fusion algorithm to highlight metrics of interest where TED orbits differed from healthy orbits.

RESULTS

Univariate analysis demonstrated several correlations between CT metrics and clinical data. Metrics pertaining to the extraocular muscles-including average diameter, maximum diameter, and muscle volume-were strongly correlated (p < 0.05) with the presence of ocular motility deficits with regards to the superior, inferior, and lateral recti (with exception of superior rectus motility deficits being mildly correlated with muscle volume [p = 0.09]). Motility defects of the medial rectus were strongly correlated with muscle volume, and only weakly correlated with average and maximum muscle diameter.

CONCLUSIONS

The novel method of automated imaging metrics may provide objective, rapid clinical information which may have utility in prevention and recognition of visual impairments in TED before they reach an advanced or irreversible stage and while they are able to be improved with immunomodulatory treatments.

Assessment of Orbital Computed Tomography (CT) Imaging Biomarkers in Patients with Thyroid Eye Disease

To understand potential orbital biomarkers generated from computed tomography (CT) imaging in patients with thyroid eye disease. This is a retrospective cohort study. From a database of an ongoing thyroid eye disease research study at our institution, we identified 85 subjects who had both clinical examination and laboratory records supporting the diagnosis of thyroid eye disease and concurrent imaging prior to any medical or surgical intervention. Patients were excluded if imaging quality or type was not amenable to segmentation. The images of 170 orbits were analyzed with the developed automated segmentation tool. The main outcome measure was to cross 25 CT structural metrics for each eye with nine clinical markers using a Kendall rank correlation test to identify significant relationships. The Kendall rank correlation test between automatically calculated CT metrics and clinical data demonstrated numerous correlations. Extraocular rectus muscle metrics, such as the average diameter of the superior, medial, and lateral rectus muscles, showed a strong correlation (p < 0.05) with loss of visual acuity and presence of ocular motility defects. Hertel measurements demonstrated a strong correlation (p < 0.05) with volumetric measurements of the optic nerve and other orbital metrics such as the crowding index and proptosis. Optic neuropathy was strongly correlated (p < 0.05) with an increase in the maximum diameter of the superior muscle. This novel method of automated imaging metrics may provide objective, rapid clinical information. This data may be useful for appreciation of severity of thyroid eye disease and recognition of risk factors of visual impairment from dysthyroid optic neuropathy from CT imaging.

Predictive parameters on CT scan for dysthyroid optic neuropathy

AIM

To evaluate the value of parameters on CT scan in predicting dysthyroid optic neuropathy (DON) and to provide guidance for early diagnosis of DON accordingly.

METHODS

A total of 67 eyes of 35 patients with thyroid-associated ophthalmopathy (TAO) were included in this study. Patients were divided into 2 groups (DON group and non-DON group). Parameters were measured on high resolution CT, including muscle index (MI), superior ophthalmic vein (SOV) dilatation, extraocular muscle volume/orbit volume (MV/OV), and intracranial fat prolapsed, and be compared between these 2 groups. The relation between those parameters and visual function [visual acuity (VA) and visual field defect (VF defect)] were also evaluated.

RESULTS

MI and MV/OV were significantly higher in DON group (P=0.00035 and P=0.00026). No significant difference was detected regarding intracranial fat prolapse existence and SOV dilatation (P=0.37 and P=0.15). MV/OV was found to have significant negative correlation with both VF defect (R=-0.332, P=0.0273) and VA (R=-0.635, P=0.00) while MI was found to have negative linear correlation with VA only (R=-0.456, P=0.00017). The area under receiver operating characteristic curves was 0.82 for MV/OV and 0.75 for MI. The best performance in detecting DON was achieved when MV/OV is set at 0.20 with 72% sensitivity and 87% specificity and MI is set at 0.52 with 64% sensitivity and 80% specificity.

CONCLUSION

MI and MV/OV are predictive parameters for DON. Together with clinical manifestations, MV/OV≥0.2 can be used as a good indicator for DON in TAO patients.

Relationship between the 24-h variability of blood pressure, ocular perfusion pressure, intraocular pressure, and visual field defect in thyroid associated orbitopathy

PURPOSE

To evaluate the relationship between the 24-h variability of blood pressure (BP), ocular perfusion pressure (OPP), intraocular pressure (IOP), and visual field (VF) defect in thyroid-associated orbitopathy (TAO).

METHODS

Thirty patients (60 eyes) with TAO were clinically examined in the Eye Hospital of Wenzhou Medical University. Patients were divided into two groups: one with VF defect (A) and the other without (B). Clinical parameters measured include 24-h IOP, 24-h blood pressure, orbital computed tomography (CT) scan, optical coherence tomography (OCT), and VFs. The pulse pressure (PP), mean arterial pressure (MAP), mean ocular perfusion pressure (MOPP), and 24-h fluctuations were calculated by formula.

RESULTS

The MOPP and MAP fluctuation were greater in group A than B (p < 0.05) and had significant negative correlation to mean deviation (MD) of VF (R = - 0.434 P = 0.001*). There was no statistical difference in the muscle index, medial rectus muscle thickness, and blood pressure between two groups. Although there were no significant differences in the mean IOP and IOP fluctuation between two groups, the incidence of IOP abnormalities has higher trend in group A. Patients with 24-h IOP fluctuation ≥8 mmHg and the mean IOP > 21 mmHg in the group A were more than group B.

CONCLUSIONS

Dysthyroid optic neuropathy (DON) might have multiple pathogenic mechanisms. In this study, 24-h MOPP fluctuation and medial rectus maximal diameter were all the risk factors for DON. Higher mean IOP and 24-h IOP fluctuation might be risk factors for DON.

Optic neuropathy and exophthalmos edematous: symptom or complication?

The article is concentrated on the mechanism of the development of optic neuropathy in patients with edematous proptosis one of the clinical forms of endocrine ophthalmopathy. All probable options for the pathogenesis of optic neuropathy are reviewed in detail: increased intraorbital pressure, compression of the optic nerve by enlarged extraocular muscles, the formation of the apical syndrome with compression of the optic nerve in the zone of the Zinns ring, an increase in the volume of orbital fat, tension of the optic nerve by an anteriorly shifted eye (exophthalmos), and arterial blood flow impairment in the ophthalmic artery, impaired venous blood flow in the orbit. Based on 103 follow-ups of patients with edematous proptosis and optic neuropathy (68 of them had initial optical neuropathy), the author offers her concept of the pathogenesis of optic neuropathy in patients with sub- and decompensated edematous proptosis, considering optic neuropathy as a complication of endocrine ophthalmopathy. The signs of optical neuropathy in the initial stage of its development are conceived.

Visual field and orbital computed tomography correlation in dysthyroid optic neuropathy due to thyroid eye disease

Purpose: The pathogenesis of dysthyroid optic neuropathy (DON) in thyroid eye disease (TED) is thought to be compression of the apical optic nerve by hypertrophied extraocular muscles. We correlated worsening DON to the area occupied by extraocular muscles.Methods: Records of adults with TED DON evaluated from 1/1/2013 to 1/1/2018 were retrospectively reviewed. Each patient's visual field with the worst mean deviation (MD) was selected. Orbit CT scans were reviewed. Reformatted oblique coronal images were created perpendicular to the optic nerve. The cross-sectional area (CSA) of the orbit and each muscle group was measured and expressed as ratios of the CSA of the orbital apex. Univariate and multivariate analysis was performed for predictors of HVF MD.Results: 34 orbits with TED DON were analyzed. On orbital CT, the superior muscle complex occupied 15% of the apex (range 6-26%), inferior 18% (range 6-33%), lateral 10% (range 4-18%), medial 17% (range 8-27%), and all combined 61% (range 28-80%). Increasing total muscle area and superior complex area correlated with worsening MD. In multivariate linear regression, the superior muscle complex remained a significant predictor of MD (p = 0.01) over total muscle area (p = 0.25).Conclusions: Enlargement of extraocular muscles is common in TED, but DON occurs in only 6%. Our findings demonstrate that as DON worsens, as quantified by visual field MD, the superior muscle complex crowds the apex. This is consistent with the typical inferior visual field findings seen in TED DON. Hypertrophy of the superior rectus and levator palpabrae superioris complex may be predictive of worsening DON.

Imaging biomarkers in thyroid eye disease and their clinical associations

The purpose of this study is to understand the phenotypes of thyroid eye disease (TED) through data derived from a multiatlas segmentation of computed tomography (CT) imaging. Images of 170 orbits of 85 retrospectively selected TED patients were analyzed with the developed automated segmentation tool. Twenty-five bilateral orbital structural metrics were used to perform principal component analysis (PCA). PCA of the 25 structural metrics identified the two most dominant structural phenotypes or characteristics, the "big volume phenotype" and the "stretched optic nerve phenotype," that accounted for 60% of the variance. Most of the subjects in the study have either of these characteristics or a combination of both. A Kendall rank correlation between the principal components (phenotypes) and clinical data showed that the big volume phenotype was very strongly correlated ( p - value < 0.05 ) with motility defects, and loss of visual acuity. Whereas, the stretched optic nerve phenotype was strongly correlated ( p - value < 0.05 ) with an increased Hertel measurement, relatively better visual acuity, and smoking. Two clinical subtypes of TED, type 1 with enlarged muscles and type 2 with proptosis, are recognizable in CT imaging. Our automated algorithm identifies the phenotypes and finds associations with clinical markers.

Management of graves myopathy: Orbital imaging in thyroid-related orbitopathy

A broad understanding of the different imaging modalities used to assess the physiologic changes seen in Graves' orbitopathy complement clinical examination. Subtle applications of radiographic imaging techniques allow for a better understanding of the overall physiology of the orbit, quantify progression of disease, and differentiate it from orbital diseases with overlapping features. A nuanced approach to interpreting imaging features may allow us to delineate inactive from active thyroid eye disease, and advances within this field may arm clinicians with the ability to better predict and prevent dysthyroid optic neuropathy.

Feasibility of a low-dose orbital CT protocol with a knowledge-based iterative model reconstruction algorithm for evaluating Graves' orbitopathy

PURPOSE

To evaluate the clinical feasibility of low-dose orbital CT with a knowledge-based iterative model reconstruction (IMR) algorithm for evaluating Graves' orbitopathy.

METHODS

Low-dose orbital CT was performed with a CTDI_vol of 4.4 mGy. In 12 patients for whom prior or subsequent non-low-dose orbital CT data obtained within 12 months were available, background noise, SNR, and CNR were compared for images generated using filtered back projection (FBP), hybrid iterative reconstruction (iDose⁴), and IMR and non-low-dose CT images. Comparison of clinically relevant measurements for Graves' orbitopathy, such as rectus muscle thickness and retrobulbar fat area, was performed in a subset of 6 patients who underwent CT for causes other than Graves' orbitopathy, by using the Wilcoxon signed-rank test.

RESULTS

The lens dose estimated from skin dosimetry on a phantom was 4.13 mGy, which was on average 59.34% lower than that of the non-low-dose protocols. Image quality in terms of background noise, SNR, and CNR was the best for IMR, followed by non-low-dose CT, iDose⁴, and FBP, in descending order. A comparison of clinically relevant measurements revealed no significant difference in the retrobulbar fat area and the inferior and medial rectus muscle thicknesses between the low-dose and non-low-dose CT images.

CONCLUSIONS

Low-dose CT with IMR may be performed without significantly affecting the measurement of prognostic parameters for Graves' orbitopathy while lowering the lens dose and image noise.

Prevalence of Radiological Signs of Dysthyroid Optic Neuropathy in Magnetic Resonance Imaging in Patients with Active, Moderate-to-Severe, and Very Severe Graves Orbitopathy

BACKGROUND

Differentiating between dysthyroid optic neuropathy (DON), which requires urgent therapy to prevent blindness, and moderate-to-severe Graves orbitopathy (GO) remains challenging. There is no pathognomonic feature of DON in either ophthalmological or radiological examinations.

OBJECTIVES

Our aim was to investigate the prevalence of radiological signs of DON in magnetic resonance imaging (MRI) in patients with moderate-to-severe and very severe GO.

METHODS

Two researchers reassessed MRI scans of 23 consecutive patients (46 eyes) with active, moderate-to-severe GO and 14 patients (23 eyes) with very severe GO. Typical signs of DON in MRI include apical crowding and optic nerve stretching. These were evaluated in the eyes of both groups of patients. Lack of cerebrospinal fluid in the optic nerve sheath as well as muscle index values were also studied. These clinical evaluations and laboratory results were then compared between groups.

RESULTS

At least one of the typical radiological features of DON was found in 22 (96%) and 16 (35%) eyes with very severe and moderate-to-severe GO, respectively. Each occurred statistically more often in patients with very severe GO. There were no ophthalmological signs of very severe GO observed in the group of patients with moderate-to-severe GO during the study or its subsequent follow-up (234 weeks).

CONCLUSIONS

MRI is a useful tool in evaluating very severe GO. However, features typical for DON are also found in up to 35% of eyes in patients with active, moderate-to-severe GO. Therefore, ophthalmological evaluation seems to be most important in the recognition of very severe GO.

[Management of moderate and severe dysthyroid orbitopathy: about 22 cases]

Décrire la prise en charge thérapeutique des orbitopathies dysthyroidiennes modérées et sévères et évaluer par une étude statistique les facteurs associés à la neuropathie optique ainsi que les facteurs de mauvais pronostic visuel. Nous avons mené une étude rétrospective sur 22 patients présentant une ophtalmopathie dysthyroidienne modérée à sévère sur au moins un oeil, hospitalisés au service d'ophtalmologie du CHU Farhat Hached Sousse, sur une période s'étalant de 1998 à 2015. Les indications thérapeutiques sont basées sur les critères d'activité et de sévérité de l'Eugogo ainsi que l'évaluation des facteurs de mauvais pronostic visuel. L'âge moyen de nos patients était de 40 ans avec une légère prédominance masculine (54.5%). 68.2% des patients étaient en euthyroidie, 18.2% étaient tabagique. Le facteur le plus associé significativement à la neuropathie est la compression au niveau de l'apex orbitaire (P = 0.03). Le traitement était basé sur la corticothérapie intraveineuse et/ou la décompression orbitaire en fonction de l'activité et la sévérité de la maladie. L'évolution globale après traitement a été marquée par une amélioration des signes inflammatoires, réduction de l'exophtalmie. Le pronostic visuel était plus mauvais chez les patients plus âgés (P = 0.0001), de sexe masculin (P = 0.03) et traités par irathérapie (P = 0.04). Dans les limites d'une étude rétrospective, nos résultats étaient globalement concordants avec la littérature. L'orbitopathie dysthyroidienne reste une maladie dont l'évaluation et la prise en charge thérapeutique sont non encore bien élucidées. Des études de cohortes, probablement multicentriques, sont à envisager pour améliorer la prise en charge.