Dysthyroid optic neuropathy: evaluation and management

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.

Functional and Morphological Changes in the Visual Pathway in Patients with Graves’ Orbitopathy

Background: The aim of the study was to perform a functional and structural evaluation of the anterior visual pathway in patients with Graves’ Orbitopathy (GO) using electrophysiological tests and OCT, as well as to identify potential parameters that could be useful in detecting early optic nerve damage. Methods: 47 GO patients were enrolled in the study and divided into three groups, depending on their disease severity: Group 1 with mild GO, Group 2 with moderate-to-severe GO, and Group 3 with dysthyroid optic neuropathy (DON). Pattern visual evoked potential (PVEP), flash visual evoked potential (fVEP), pattern electroretinogram (pERG), and optical coherence tomography (OCT) findings were compared between the groups. Results: In the DON Group (Group 3), N75, P100, and P2 latencies were significantly extended, whereas P100, P50, and N95 amplitudes were significantly reduced as compared to the non-DON group (Groups 1 and 2). Group 3 also had significantly thinner peripapillary retinal nerve fiber layer (RNFL) and macular ganglion cell complex (GCC). In Group 2, as compared to Group 1, P100 amplitudes were significantly reduced for all check sizes, while P100 latency was elongated for the check size of 0.9°. Group 2 also had a significantly thinner average GCC and GCC in the superior quadrant. Conclusions: Electrophysiological examinations may be of use in diagnosis of DON. OCT findings and electrophysiological responses vary in patients with different GO severity. Including regular electrophysiological evaluation and OCT in the examination of patients with GO could be of benefit. However, more research is needed to establish the true significance of pVEP, fVEP, pERG, and OCT in monitoring patients with GO.

Morphological brain changes between active and inactive phases of thyroid associated ophthalmopathy: a voxel-based morphometry study

AIM

To explore the morphological brain changes among active thyroid-associated ophthalmopathy (TAO) patients, inactive TAO patients and healthy controls and to investigate the neuropathological relationship of TAO using magnetic resonance imaging (MRI) data.

METHODS

In this observational case-control study, we included 35 inactive TAO patients, 37 active TAO patients and 23 healthy controls. Voxel-based morphometry (VBM) analysis was conducted to evaluate the gray matter volume (GMV) changes among groups, and the correlations between GMV alterations and clinical parameters in active and inactive TAO groups were investigated.

RESULTS

Active TAO patients showed significantly increased GMV in the right inferior frontal gyrus, left superior frontal gyrus (SFG), orbital superior frontal gyrus, orbital middle frontal gyrus, precuneus and postcentral gyrus compared with controls and significantly increased GMV in the right middle temporal gyrus, left SFG and precuneus compared with the inactive TAO group. No significant differences were observed between the inactive TAO group and healthy controls. Notably, the receiver operating characteristic (ROC) curve analysis demonstrated altered GMV among groups and significantly (p<0.001) differentiated active TAO from inactive TAO and healthy controls. In addition, the mean GMV in precuneus and postcentral gyrus were significantly associated with clinical parameters in active TAO.

CONCLUSION

Our findings suggested the localized GMV alterations among groups were associated with the pathophysiology of TAO and served as a potential discriminative pattern to detect clinical phases of TAO at the individual level. The altered brain morphometry may suggest a corresponding process of self-repair and remodeling of the brain structure as the disease progresses in TAO.

Assessment of Orbital Compartment Pressure: A Comprehensive Review

The orbit is a closed compartment defined by the orbital bones and the orbital septum. Some diseases of the orbit and the optic nerve are associated with an increased orbital compartment pressure (OCP), e.g., retrobulbar hemorrhage or thyroid eye disease. Our aim was to review the literature on the different approaches to assess OCP. Historically, an assessment of the tissue resistance provoked by the retropulsion of the eye bulb was the method of choice for estimating OCP, either by digital palpation or with specifically designed devices. We found a total of 20 articles reporting direct OCP measurement in animals, cadavers and humans. In nine studies, OCP was directly measured in humans, of which five used a minimally invasive approach. Two groups used experimental/custom devices, whilst the others applied commercially available devices commonly used for monitoring the compartment syndromes of the limbs. None of the nine articles on direct OCP measurements in humans reported complications. Today, OCP is mainly estimated using clinical findings considered surrogates, e.g., elevated intraocular pressure or proptosis. These diagnostic markers appear to reliably indicate elevated OCP. However, particularly minimally invasive approaches show promises for direct OCP measurements. In the future, more sophisticated, specifically designed equipment might allow for even better and safer measurements and hence facilitate the diagnosis and monitoring of orbital diseases.

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.

Functional outcomes and complications in refractory dysthyroid optic neuropathy management: Experience with 3 different surgical protocols

INTRODUCTION

Dysthyroid optic neuropathy (DON) is the most severe complication of Graves' orbitopathy (GO) and its management may require decompression surgery. Clear recommendations do not exist about which surgery should be performed and how extended the decompression should be. In this paper we present our experience regarding the management of DON via 3 different surgical protocols: a modified extended orbital apex decompression, a 2 walls decompression (inferior and lateral) and a 3 walls decompression (inferior, lateral and medial) and evaluate the functional outcomes.

METHODS

Retrospective evaluation of subjects affected by DON not responding to medical therapy has been performed. All patients were submitted to pre- and post-operative ophthalmologic evaluations and orbital and sinuses CT scan in order to evaluate functional and surgical outcomes.

RESULTS

27 patients were enrolled in the study. Surgical procedures were performed on 42 orbits. A statistically significant post-operative improvement was recorded in visual acuity, proptosis, color vision and fundus oculi evaluation for all groups. No patient developed major or minor complications after surgery.

CONCLUSIONS

Extended endonasal approach and 3 walls decompression have been proved effective in the management of DON. The choice between them is done according to degree of proptosis, general status and eye-surface damages.

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.

Comparison of the decompressive effect of different surgical procedures for dysthyroid optic neuropathy using 3D printed models

PURPOSE

To compare the decompressive effect around the optic nerve canal among 3 different decompression procedures (medial, balanced, and inferomedial) using 3D printed models.

METHODS

In this experimental study, based on data obtained from 9 patients (18 sides) with dysthyroid optic neuropathy, a preoperative control model and 3 plaster decompression models were created using a 3D printer (total, 72 sides of 36 models). A pressure sensor was placed at the optic foramen, and the orbital space was filled with silicone. The surface of the silicone was pushed down directly, and changes in pressure were recorded at 2-mm increments of pushing.

RESULTS

At 10 mm of pushing, there was significantly lower pressure in the medial (19,782.2 ± 4319.9 Pa, P = 0.001), balanced (19,448.3 ± 3767.4 Pa, P = 0.003), and inferomedial (15,855.8 ± 4000.7 Pa, P < 0.001) decompression models than in the control model (25,217.8 ± 6087.5 Pa). Overall, the statistical results for each 2-mm push were similar among the models up to 10 mm of pushing (P < 0.050). At each push, inferomedial decompression caused the greatest reduction in pressure (P < 0.050), whereas there was no significant difference in pressure between the medial and balanced decompression models (P > 0.050).

CONCLUSION

All 3 commonly performed decompression procedures significantly reduced retrobulbar pressure. Because inferomedial decompression models obtained the greatest reduction in pressure on the optic nerve canal, inferomedial decompression should be considered the most reliable procedure for rescuing vision in dysthyroid optic neuropathy.

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.

Ocular manifestations of endocrine disorders

Endocrinopathies are prevalent diseases that typically affect multiple organs, and the eye and orbital tissues are often involved in endocrine disorders. Some conditions, such as diabetes and thyroid gland dysfunction, may cause serious eye pathology and even blindness. A clear insight into the pathogenesis of endocrinopathies and their ocular manifestations would enhance preventive and therapeutic measures and reduce the incidence of sight-threatening complications. This review discusses the ocular manifestations of several endocrine disorders that eye care providers are likely to encounter in clinical practice.

[Graves' orbitopathy]

BACKGROUND

 Graves' orbitopathy (GO) is an autoimmune orbital disease which is mostly associated with Graves' disease and requires good interdisciplinary cooperation. To minimize irreversible damages a stage-adapted anti-inflammatory therapy is of great importance.

MATERIAL AND METHODS

 Discussion of the latest results of new findings of the pathogenesis, randomized controlled trials on anti-inflammatory treatments for Graves' orbitopathy and novel therapeutic concepts.

RESULTS

 In all patients with GO achieving euthyroidism, as well as cessation of smoking is very important to avoid prolongated diseases. Mild cases of GO can be treated with selenium supplementation and artificial tears. The moderate-to-severe, active form of GO requires primarily i. v. steroids in combination with orbital irradiation in case of impaired motility. In patients with insufficient therapeutic response after 6 weeks, treatment should be switched to other immunosuppressive agents. In severe sight-threatening cases even high-dose i. v. steroid treatments are often ineffective and bony orbital decompression is necessary. As latest research data have improved our understanding of the pathophysiology of GO, targeted therapies have been developed for GO. Teprotumumab, an IGF-1 receptor antibody, was shown effective in treating GO patients in a phase III trial and should soon be awarded approval for Europe. Inactive patients, who suffer from disturbing exophthalmos should be also treated with bony decompression before eye muscle or lid surgery.

CONCLUSION

 The current concept for Graves' orbitopathy is as follows: first anti-inflammatory therapy then surgical correction of the permanent defects. This might be modified in the future, due to the promising effects of targeted therapies.

Graves' orbitopathy: a multidisciplinary approach

Orbitopathy is the main extra thyroidal manifestation of Graves' disease. It is a very challenging condition, which requires a cooperation between many specialists (endocrinologists, ophthalmologists, radiologists, radiotherapeutic, orbital surgeons) for an optimal clinical management. An accurate diagnostic assessment is required, in order to plan an adequate treatment of Graves' orbitopathy. Medical therapy, radiotherapy or surgery may be necessary to control the disease. In this review, the authors analyze the various therapeutic strategies, as well the more recent therapies based on pharmacologic immunomodulation.

Sight-Threatening Graves' Ophthalmopathy during the Third Trimester of Pregnancy: A Case Report

Dysthyroid optic neuropathy is a severe manifestation of Graves' ophthalmopathy that can result in permanent vision loss. We report a 37-year-old pregnant woman with Graves' ophthalmopathy which was deteriorated to dysthyroid optic neuropathy in the third trimester of pregnancy. Diplopia, bilateral eye lid retraction, lid edema and proptosis were observed in the 29th week of gestation. Thyroid-stimulating hormone (TSH) level was decreased with a normal level of free triiodothyronine (FT3) and an upper normal level of free thyroxine (FT4). Anti-TSH receptor antibodies (16.2 IU/L, reference range < 2.0 IU/L) and thyroid stimulating antibody (4,443%, reference range < 120%) were positive. Magnetic resonance imaging (MRI) demonstrated a significant enlargement of the extraocular muscles with a high signal intensity on T2-weighted image. She was diagnosed as Graves' ophthalmopathy and subclinical hyperthyroidism, and followed without treatment. In the 34th week of gestation, the symptom of color vision abnormality appeared, suggesting dysthyroid optic neuropathy. She delivered a female infant during the 36th week of gestation. Four days after delivery, she had a spontaneous orbital pain. MRI showed that the extraocular muscles were more enlarged than the findings in the 29th week of gestation. FT3 and FT4 levels were mildly elevated. Dysthyroid optic neuropathy was diagnosed. She was treated with methylprednisolone pulse therapy and retrobulbar injections of betamethasone valerate, and the ocular symptoms improved. The present case shows that the glucocorticoid therapy performed one week after delivery is effective against Graves' ophthalmopathy which was deteriorated to dysthyroid optic neuropathy during the third trimester of pregnancy.