Neuronavigation in endoscopic skull base surgery and the accuracy of different MRI sequences.

OBJECTIVE: Neuronavigation is common technology used by skull base teams when performing endoscopic endonasal surgery. A common practice of MRI imagining is to obtain 3D isotopic gadolinium enhanced T1W magnetisation prepared rapid gradient echo (MPRAGE) sequences. These are prone to distortion when undertaken on 3 T magnets. The aim of this project is to compare the in vivo accuracy of MRI sequences between current and new high resolution 3D sequences. The goal is to determine if geometric distortion significantly affects neuronavigation accuracy. METHODS: Patients were scanned with a 3D T1 MPRAGE sequence, 3D T1 SPACE sequence and a CT stereotactic localisation. Following general anaesthesia, patients were registered on the Stealth Station (Medtronic, USA) using a side mount emitter for Electromagnetic navigation. A variety of surgically relevant anatomical landmarks in the sagittal and coronal plane were selected with real and virtual data points measured. RESULTS: A total of 10 patients agreed be enrolled in the study with datapoints collected during surgery. The distance between real and virtual datapoints trended to be lower in SPACE sequences compared to MPRAGE. Paired t test did not demonstrate a significant difference. CONCLUSION: We have demonstrated that navigational accuracy is not significantly affected by the type of MRI sequence selected and that current corrective algorithms are sufficient. Navigational accuracy is affected by many factors, with registration error likely playing the most significant role. Further research involving real time imaging such as endoscopic ultrasound may hopefully address this potential error.

A case of disseminated nocardiosis with orbital apex involvement and endophthalmitis.

Nocardia is a rare cause of ocular infections and most commonly occurs secondary to trauma. Systemic Nocardiosis may have ocular involvement in rare cases. We report a case of disseminated nocardiosis with orbital apex involvement and endophthalmitis in an immunocompromised patient. The patient presented with respiratory sepsis, and later developed complete ptosis and ophthalmoplegia in the left eye. This was on the background of treatment with high-dose prednisolone. Magnetic resonance imaging showed enhancement of the entire clivus, extending into the left orbital apex and cavernous sinus. The patient was initially treated empirically for CNS tuberculosis. Bronchoscopic cultures returned positive for Nocardia farcinica, and the patient was treated with trimethoprim/sulfamethoxazole and weaned off previous corticosteroids.

Qualitative and Quantitative Magnetic Resonance Imaging in Bacterial Orbital Cellulitis.

PURPOSE: To summarise the qualitative and quantitative parameters of bacterial orbital cellulitis (OC) on magnetic resonance imaging (MRI) and explore their clinical correlations. METHODS: Multi-centre retrospective study with inclusion of patients of all ages with OC who underwent MRI. Patients with isolated pre-septal cellulitis, bilateral disease and poor-quality scans were excluded. An enlargement ratio for extraocular muscles (EOMs) was calculated by dividing maximal EOM measurements from the affected side by the contralateral side. RESULTS: Twenty MRI scans from twenty patients (Mean age: 40.8 ± 24.3 years old, M: F = 15:5) between 2011 and 2022 were analysed. Three (15.0%) cases were paediatric patients (<18 years old). All cases had both pre-septal and orbital fat involvement. The EOM were affected in nineteen cases, with the superior muscle complex (18/19, 94.7%) most commonly affected. Mean enlargement ratio (1.30, Range: 1.04-1.82) was greatest for the medial rectus on axial views on T1 and fat-suppressed contrast-enhanced T1 (FS CE T1). Optic peri-neuritis was present in eleven (55.0%) patients, whilst two (9.5%) cases had optic neuritis. A greater degree of proptosis was observed in patients with optic neuropathy and those who underwent surgical intervention compared to those without (p = .002 and p = .002, respectively). CONCLUSION: MRI remains an important imaging modality for evaluating complicated OC. However, qualitative features may lack accuracy and is not a reproducible means of analysis. Simple quantitative parameters, such as proptosis and EOM measurements, correlate with high-risk clinical features and may have utility in predicting clinical course.

Asymmetric proptosis in thyroid eye disease.

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

Magnetic Resonance Imaging of Idiopathic Orbital Myositis.

PURPOSE: To characterize the qualitative and quantitative features of idiopathic orbital myositis (IOM) on MRI. METHODS: This was a multicenter retrospective study of patients with active IOM with MRI. Patients with incomplete clinical records, poor-quality or interval scans without active myositis, and specific orbital myositis (i.e., orbital myositis secondary to an identified condition) were excluded. An enlargement ratio was calculated by dividing the diameters of the affected extraocular muscle (EOM) by the contralateral unaffected EOM. RESULTS: Twenty-four patients (mean age: 44.4 ± 17.8 years-old, male: 11) between 2011 and 2022 were included. One case (4.2%) was pediatric (17 years old), and 6 cases presented with recurrence. Active IOM was characterized by fusiform EOM enlargement, high T2 signal, and contrast enhancement. Average maximal EOM diameters ranged from 4.6 to 7.7 mm (enlargement ratio: 1.4-2.2). Eighteen (75%) patients had single EOM involvement, most commonly the medial rectus. Other ipsilateral structures affected included focal orbital fat (16/24, 66.7%) and lacrimal gland (8/24, 33.3%). Contralateral changes in the EOM and/or lacrimal gland were observed in 7 patients (29.2%). Patients presenting with recurrence were likely to develop ongoing recurrent episodes (p = 0.003). CONCLUSIONS: Various radiological patterns of involvement described including EOM enlargement, contrast enhancement, abnormal signal, and involvement of other orbital structures are indicative of active IOM. IOM remains a heterogeneous spectrum of acute and chronic clinico-radiological presentations. Inflammation may involve other ipsilateral or contralateral orbital structures or may be bilateral despite presenting clinically as unilateral disease. Quantitative measurements may have utility in differentiating IOM from other causes of orbital myositis.

Optic nerve sheath infiltration in dysthyroid optic neuropathy.

PURPOSE: To assess the association of optic nerve sheath (ONS) infiltration, fat infiltration, and scleral enhancement with active thyroid eye disease (TED) and dysthyroid optic neuropathy (DON). METHODS: Thyroid eye disease patients who had axial and coronal fat-suppressed contrast enhanced T1-weighted magnetic resonance imaging (MRI) imaging performed were included. Optic nerve sheath infiltration was defined by the presence of thickening and circumferential enhancement of the optic nerve sheath. Clinical assessments were performed by orbital surgeons or neuro-ophthalmologists and the disease activity (active/inactive) and presence or absence of dysthyroid optic neuropathy were recorded. RESULTS: The study population consisted of 76 orbits from 38 patients with a mean age of 53 ± 15 years, with 25 (66%) being female. Optic nerve sheath infiltration was present in 28 (37%) orbits, fat infiltration in 37 (49%) and scleral enhancement in 14 (18%) orbits. ONS infiltration (OR 19.8, p < 0.01), fat infiltration (OR 5.2, p < 0.01) and scleral enhancement (OR 12.2, p = 0.01) were all significantly associated with active clinical disease. Patients with ONS infiltration had a significantly higher odds of dysthyroid optic neuropathy (OR 3.4, p < 0.05). Fat infiltration (OR 2.8, p = 0.1) and scleral enhancement (OR 2.3, p = 0.23) were not significantly associated with DON. CONCLUSIONS: Optic nerve sheath infiltration may be a predictor of dysthyroid optic neuropathy. Intraorbital fat infiltration and scleral enhancement may be used to detect active TED. These radiological findings may serve as useful diagnostic and stratification tools in evaluating TED patients.

Extraocular muscle enlargement and proptosis in carotid cavernous fistulas.

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

A Pilot Study of Dynamic Magnetic Resonance Dacryocystography Imaging to Assess Functional Epiphora.

OBJECTIVE: To evaluate dynamic magnetic resonance dacryocystography (MRDCG) in eyes with functional epiphora. METHODS: We included prospective eyes with epiphora if no alternative cause was found on clinical examination, were patent on syringing, had no obstruction or stenosis on DCG, and had an abnormal DSG. MRDCG was performed to qualitatively assess for block or patency and quantitatively measure tear transit time. We compared measurements to asymptomatic fellow eyes and to historical reference values from asymptomatic eyes. RESULTS: We included 26 symptomatic eyes of 19 patients (median age 63 years). There was a block on MRDCG in 18 (69%) eyes and patency in 8 (31%) eyes. The block occurred at the sac-nasolacrimal duct (NLD) junction in 9 (50%), proximal NLD in 5 (28%), mid-NLD in 1 (5.6%), and distal NLD in 1 (5.6%) eye(s). No contrast was observed in the lacrimal system in two eyes. For eyes patent on MRDCG, median times to the sac, NLD, inferior meatus, first 25%, and first 50% of the fundus-to-nose distance (FND) were 22, 54, 118, 34, and 84 s, respectively. Times to the sac, NLD, and to fill the first 25% and 50% of the FND were significantly longer than historical values from asymptomatic lacrimal systems (p = 0.017, 0.050, 0.035, 0.017, respectively). CONCLUSION: MRDCG shows a high rate of block in functional epiphora. However, DSG and MRDCG results may not always correlate. The improved temporal resolution of this emerging modality may be advantageous in the critical first 2 min of tear transit.

Plexiform Schwannoma of the Eyelid.

Plexiform schwannoma of the lacrimal gland of the palpebral lobe has not been previously described. This 41-year-old male presented with a 2-year history of a left upper eyelid mass and associated regional irritation. MRI of the head and orbits confirmed a left superolateral multinodular mass centered on the palpebral lobe of the left lacrimal gland. Excision revealed a schwannoma of the plexiform subtype.

Extraocular muscle enlargement in dysthyroid optic neuropathy.

OBJECTIVE: To investigate extraocular muscle volumes in thyroid eye disease (TED) patients with and without dysthyroid optic neuropathy (DON). DESIGN: Retrospective cohort study. PARTICIPANTS: TED patients who had computed tomography of the orbits. METHODS: The extraocular muscles were manually segmented in consecutive axial and coronal slices, and the volume was calculated by summing the areas in each slice and multiplying by the slice thickness. Data were collected on patient demographics, disease presentation, thyroid function tests, and antibody levels. RESULTS: Imaging from 200 orbits was evaluated. The medial rectus, lateral rectus, superior muscle group, inferior rectus, and superior oblique volumes were significantly greater in orbits with DON compared with TED orbits without DON (p < 0.01 for all). There was no significant difference in the inferior oblique muscle volume (p = 0.19). Increase in volume of the superior oblique muscle showed the highest odds for DON. Each 100 m3 increase in superior oblique, lateral rectus, inferior rectus, medial rectus, and superior muscle group volume was associated with 1.58, 1.25, 1.20, 1.16, and 1.14 times increased odds of DON. CONCLUSION: All extraocular muscle volumes except for the inferior oblique were significantly greater in DON patients. Superior oblique enlargement was associated with the highest odds of DON, suggesting superior oblique enlargement to be a novel marker of DON.

Cutaneous squamous cell carcinoma radiographically mimicking infiltration into the lacrimal gland.

Cutaneous squamous cell carcinoma (SCC) is a common malignancy of the skin, with the potential for local invasion and metastasis. Here, we present a case series of two patients with SCCs, suggesting radiological infiltration of the lacrimal gland on magnetic resonance imaging. However, histopathological examination revealed lymphoplasmacytic infiltration of the lacrimal gland consistent with dacryoadenitis, with no evidence of SCC infiltration. Our cases highlight the potential for peritumoural inflammation to cause dacryoadenitis and radiologically mimic tumour infiltration into the lacrimal gland.

Imaging of dysthyroid optic neuropathy.

Dysthyroid optic neuropathy (DON) is a sight-threatening complication of thyroid eye disease and can lead to permanent vision loss if not treated early. Imaging with computed tomography (CT) or magnetic resonance imaging (MRI) can aid in the diagnosis and early recognition of DON. A number of quantitative and qualitative imaging features have been associated with DON. This article summarises the definition, prevalence, and utility of these radiological findings in the diagnosis of DON.

Dilated superior ophthalmic vein: systemic associations.

PURPOSE: To review systemic associations of patients with dilated superior ophthalmic veins (SOV) in the absence of orbital, cavernous sinus, or neurological disease. METHODS: Retrospective review of patients who had dilated SOVs with a diameter of ≥ 5.0 mm. Patients with a dilated SOV secondary to orbital, cavernous sinus or neurological disease were excluded. Patient demographics, past medical history, and SOV diameters on initial and follow up scans were collected. The maximum diameter of the SOV was taken perpendicular to the long axis of the SOV. RESULTS: Nine cases were identified. Patients ranged in age from 58 to 89 years and six out of nine were female. The dilated SOV involved both eyes in two cases, left eye in five cases and right eye in two cases. Three patients had dilated SOV likely secondary to raised venous pressures from decompensated right heart failure (n = 1), pericardial effusion (n = 1) and left ventricle dysfunction secondary to a myocardial infarction (n = 1). Five patients had a significant history of previous ischaemic heart or peripheral vascular disease. Two patients had risk factors for venous clotting disease whilst one patient had a history of giant cell arteritis and vertebral artery dissection. CONCLUSION: A dilated SOV may raise concern for life threatening conditions such as a carotid cavernous fistula and may prompt additional investigations. A dilated SOV may be reversible and secondary to raised venous pressures due to cardiac failure. Other cases may be seen in patients with significant cardiovascular risk factors, possibly due to changes in vasculature.

Orbital Artifacts on MRI.

PURPOSE: To describe artifacts on orbital MRI, which led to an incorrect radiology report. METHODS: Retrospective chart review of patients identified from the orbital databases at the Royal Adelaide Hospital and University of Wisconsin Hospital. Patients who had artifacts on orbital MRI that led to an incorrect radiology report were included. Records were evaluated for age at imaging, gender, MRI sequence, laterality, and location of artifact, radiological characteristics and misdiagnosis, and cause of artifact. RESULTS: Data were collected from 7 patients (3 male) who had a median age of 61 years at the time of imaging. Five artifacts resulted from fat-suppression failure with 4 of these cases misdiagnosed as inflammatory changes and 1 misdiagnosed as neoplastic infiltration. The OD was involved in 4 cases. Six cases were in the inferior orbit region. CONCLUSIONS: Fat-suppression failure artifacts may arise in the inferior orbit region and can be mistaken for inflammatory or neoplastic orbital disease. This may prompt additional investigations such as orbital biopsy. Clinicians should be aware of artifacts which can affect orbital MRI and lead to potential misdiagnosis.

Orbital inflammation following COVID-19 vaccination: A case series and literature review.

PURPOSE: The purpose of the study was to report three cases of orbital inflammation following administration of the COVID-19 vaccination, manifesting as Tolosa-Hunt syndrome (THS) and orbital myositis. METHOD: A retrospective case series and literature review of patients who developed orbital inflammation following a COVID-19 vaccination. RESULTS: One patient presented with Tolosa-Hunt syndrome (THS) 14 days following her third (booster) COVID-19 vaccination, one patient developed orbital myositis 10 days following his first COVID-19 vaccination and one patient developed recurrent orbital myositis 1 and 7 days following her second and fourth COVID-19 vaccination. All patients received the Comirnaty vaccine (Pfizer-BioNTech). A thorough systemic autoimmune disease workup in both patients was unremarkable. Two patients had a prior history of orbital inflammation, with previous involvement of other different orbital structures. Characteristic MRI features for each pathology were observed, supporting the clinical presentation of THS and orbital myositis. There was complete resolution of THS following corticosteroids, with no recurrence at 2 months. Meanwhile, one case of orbital myositis self-resolved at 2 months without use of systemic corticosteroids, while the other patient with orbital myositis required treatment with intra-orbital steroid injections and oral corticosteroids. CONCLUSION: Orbital inflammation has been recognised as a rare adverse effect following COVID-19 vaccination. We present a case series of THS and orbital myositis as varied presentations of this entity.

Methicillin-resistant Staphylococcus aureus-associated orbital cellulitis: a case series.

PURPOSE: In recent years, methicillin-resistant Staphylococcus aureus (MRSA) orbital cellulitis (OC) has drawn increasing clinical and public health concern. We present a case series of MRSA OC encountered at four Australian tertiary institutions. METHODS: A multi-centre retrospective case series investigating MRSA OC in Australia from 2013 to 2022. Patients of all ages were included. RESULTS: Nine cases of culture-positive non-multi-resistant MRSA (nmMRSA) OC were identified at four tertiary institutions across Australia (7 male, 2 female). Mean age was 17.1 ± 16.7 years (range 13-days to 53-years), of which one was 13 days old, and all were immunocompetent. Eight (88.9%) patients had paranasal sinus disease, and seven (77.8%) had a subperiosteal abscess. Four (44.4%) had intracranial extension, including one (11.1%) case which was also complicated by superior sagittal sinus thrombosis. Empirical antibiotics, such as intravenous (IV) cefotaxime alone or IV ceftriaxone and flucloxacillin, were commenced. Following identification of nmMRSA, targeted therapy consisting of vancomycin and/or clindamycin was added. Nine (100%) patients underwent surgical intervention. Average hospital admission was 13.7 ± 6.9 days (range 3-25 days), with two patients requiring intensive care unit (ICU) admission due to complications related to their orbital infection. All patients had favourable prognosis, with preserved visual acuity and extraocular movements, following an average follow-up period of 4.6 months (range 2-9 months). CONCLUSION: NMMRSA OC can follow an aggressive clinical course causing severe orbital and intracranial complications across a wide demographic. However, early recognition, initiation of targeted antibiotics and surgical intervention when required can effectively manage these complications and achieve favourable visual outcomes.

Evaluating the Ability of Open-Source Artificial Intelligence to Predict Accepting-Journal Impact Factor and Eigenfactor Score Using Academic Article Abstracts: Cross-sectional Machine Learning Analysis.

BACKGROUND: Strategies to improve the selection of appropriate target journals may reduce delays in disseminating research results. Machine learning is increasingly used in content-based recommender algorithms to guide journal submissions for academic articles. OBJECTIVE: We sought to evaluate the performance of open-source artificial intelligence to predict the impact factor or Eigenfactor score tertile using academic article abstracts. METHODS: PubMed-indexed articles published between 2016 and 2021 were identified with the Medical Subject Headings (MeSH) terms "ophthalmology," "radiology," and "neurology." Journals, titles, abstracts, author lists, and MeSH terms were collected. Journal impact factor and Eigenfactor scores were sourced from the 2020 Clarivate Journal Citation Report. The journals included in the study were allocated percentile ranks based on impact factor and Eigenfactor scores, compared with other journals that released publications in the same year. All abstracts were preprocessed, which included the removal of the abstract structure, and combined with titles, authors, and MeSH terms as a single input. The input data underwent preprocessing with the inbuilt ktrain Bidirectional Encoder Representations from Transformers (BERT) preprocessing library before analysis with BERT. Before use for logistic regression and XGBoost models, the input data underwent punctuation removal, negation detection, stemming, and conversion into a term frequency-inverse document frequency array. Following this preprocessing, data were randomly split into training and testing data sets with a 3:1 train:test ratio. Models were developed to predict whether a given article would be published in a first, second, or third tertile journal (0-33rd centile, 34th-66th centile, or 67th-100th centile), as ranked either by impact factor or Eigenfactor score. BERT, XGBoost, and logistic regression models were developed on the training data set before evaluation on the hold-out test data set. The primary outcome was overall classification accuracy for the best-performing model in the prediction of accepting journal impact factor tertile. RESULTS: There were 10,813 articles from 382 unique journals. The median impact factor and Eigenfactor score were 2.117 (IQR 1.102-2.622) and 0.00247 (IQR 0.00105-0.03), respectively. The BERT model achieved the highest impact factor tertile classification accuracy of 75.0%, followed by an accuracy of 71.6% for XGBoost and 65.4% for logistic regression. Similarly, BERT achieved the highest Eigenfactor score tertile classification accuracy of 73.6%, followed by an accuracy of 71.8% for XGBoost and 65.3% for logistic regression. CONCLUSIONS: Open-source artificial intelligence can predict the impact factor and Eigenfactor score of accepting peer-reviewed journals. Further studies are required to examine the effect on publication success and the time-to-publication of such recommender systems.

Case Report: Late spontaneous orbital subperiosteal hematoma after endoscopic sinonasal tumor resection.

INTRODUCTION AND IMPORTANCE: We report a case of spontaneous subperiosteal orbital hematoma many years after endoscopic sinonasal resection of malignancy. CASE PRESENTATION: A 50-year-old female with a six-year history of endoscopic sinonasal resection of a poorly differentiated neuroendocrine tumor presented with two days of worsening frontal headache and left periocular swelling. A subperiosteal abscess was initially suspected on CT; however, MRI sequences revealed changes consistent with the diagnosis of hematoma. A conservative approach was justified based on the clinico-radiologic features. Progressive clinical resolution was noted over three weeks. Two monthly follow-up MRI revealed resolution of the orbital findings with no features to indicate recurrence of malignancy. CLINICAL DISCUSSION: Subperiosteal pathologies can be clinically challenging to differentiate. Differing radiodensities on CT may help differentiate between them but is not always reliable. MRI is more sensitive and is the preferred imaging modality. CONCLUSION: Spontaneous orbital hematomas are self-resolving, and surgical exploration may be avoided in the absence of complications. Therefore, it is beneficial to recognize it as a potential late complication of extensive endoscopic endonasal surgery. Characteristic features on MRI can aid diagnosis.

Disseminated thrombosis of the internal jugular vein, superior ophthalmic vein and cavernous sinus as the primary manifestation of occult malignancy: a case report.

Internal jugular vein (IJV) thrombosis is a life-threatening condition most often associated with local risk factors such as head or neck infection or central venous catheterisation. Underlying malignancy is a rare but important aetiology to consider in patients presenting with spontaneous IJV thrombosis. We describe a case of necrotic cervical lymphadenopathy with thrombosis of the IJVs, cavernous sinuses and superior ophthalmic veins in a patient with metastatic squamous cell carcinoma, which was further complicated by an orbital compartment syndrome. The differential diagnosis of IJV thrombosis includes a range of infective, metastatic and thrombophilic pathologies. This case illustrates that, in the absence of an underlying precipitating factor, spontaneous IJV thrombosis should prompt further systemic investigations. Furthermore, patients with thrombotic events affecting the orbital venous drainage system should be monitored closely for signs of an acute orbital compartment syndrome.