Superficial ocular vascular changes after orbital decompression in patients with thyroid ophthalmopathy measured by anterior segment OCT angiography; an observational study.

Thyroid eye disease (TED) is a common ophthalmologic manifestation of thyroid dysfunction. Despite various imaging techniques available, there hasn't been a widely adopted method for assessing the anterior segment vasculature in TED patients. Our study aimed to evaluate alterations in ocular surface circulation following orbital decompression surgery in TED patients and investigate factors influencing these changes. Using anterior segment optical coherence tomography-angiography (AS-OCTA), we measured ocular surface vascularity features, including vessel density (VD), vessel diameter index (VDI), and vessel length density (VLD), both before and after decompression surgery, alongside standard ophthalmic examinations. Our AS-OCTA analysis revealed a significant decrease in most of the temporal vasculature measurements six weeks post-surgery (p < 0.05). However, differences in the nasal region were not statistically significant. These findings indicate notable changes in ocular surface circulation following orbital decompression in TED patients, which may have implications for intraocular pressure (IOP) control and ocular surface symptoms management. AS-OCTA holds promise as a tool for evaluating the effectiveness of decompression surgery and assessing the need for further interventions.

Endoscopically managed giant frontoethmoidal osteoma with orbital extension.

A patient in his 20s presented with a change in the appearance of his left eye with evidence of relative afferent pupillary defect. Imaging revealed a giant frontoethmoidal osteoma, a benign sinonasal tumour, invading three-quarters of the orbit. Multidisciplinary discussion involving opthalmology, maxillofacial surgery, neurosurgery and otolaryngology resulted in the decision to attempt entirely endoscopic excision of this lesion, which was performed with successful outcomes. This case demonstrates how a sinonasal osteoma should be considered in the differential diagnosis for a patient presenting with proptosis or other eye signs suggestive of compression of the orbital compartment. This case report and literature review highlights the possibility of managing giant sinonasal osteomas with orbital extension through a completely endoscopic approach.

Superior ophthalmic vein thrombosis in unique double origin: a case report.

Superior ophthalmic vein thrombosis (SOVT) is a rare orbital pathology. It can cause serious complications if it isn´t diagnosed appropriately. It can be secondary to many etiologies, septic or aseptic ones. Diabetic ketoacidosis (DKA) may disturb the vascular endothelium and promote a prothrombotic state. The presence of which is related to a significantly increased risk of morbidity and mortality. We report the case of a 45-year-old woman who presented a SOVT revealing DKA. Orbit magnetic resonance imaging (MRI) showed thrombosis of the right superior ophthalmic vein. A treatment based on thrombolytic treatment, associated with antibiotic coverage and a glycemic balance was initiated. This case highlights the importance of considering both infection and diabetes as an important part of the diagnosis and management of SOVT.

Morphometric evaluation of the anatomical relationships between the superior orbital fissure and the orbital structures based on computed tomography images with clinical implications.

PURPOSE: To assist in surgical planning in endoscopic approaches, we analyzed the morphometric measurements of the superior orbital fissure (SOF) and optic canal (OC) by three-dimensional multislice computed tomography (3D MDCT) and evaluated them according to age, gender, and lateralization. METHODS: The study analyzed 219 MDCT images (114 women, 105 men) from individuals aged 18-90. Measurements of SOF and OC were performed on 3D MDCT images in the axial plane and with 3D-Slicer software. RESULTS: The distance between the infraorbital foramen and the anterior entrance of the maxillary sinus (CBW) (p < 0.001), the distance between the CBW and the lateral point of the SOF (p = 0.001), and the Angle 1 (p = 0.028) were higher in women than in men. While the SOF length and on 3D the SOF width were higher in women than men (p < 0.001 and (p = 0.001, respectively), the lateral wall length OC was higher in men than women (p = 0.045). According to SOF classification, SOF length was highest in type II and lowest in type VIII (p = 0.025), SOF width was highest in type I and lowest in type VI (p < 0.001). No significant difference was found based on age groups and lateralization in all parameters. CONCLUSION: We found that as the SOF width increased, the SOF length also increased, and there was a statistically strong positive correlation. These findings can contribute to a more effective and safe operation by improving and updating surgeons' knowledge about safe distances to SOF in endoscopic procedures from a 3D MDCT perspective.

Validating the Supraorbital Notch-Nasion-Supraorbital Notch Angle as a Marker for Metopic Craniosynostosis Severity.

OBJECTIVE: Metopic craniosynostosis (MCS) can be difficult to differentiate from metopic ridge (MR) or normal frontal morphology. This study assess whether the supraorbital notch-nasion-supraorbital notch (SNS) angle can help identify MCS. METHODS: Records of 212 patients with preoperative three-dimensional computed tomography scans were examined. The SNS angles, surgeon craniofacial dysmorphology rankings, and CranioRate metopic severity scores (MSSs) were compared with the Spearman rank correlation coefficient. Receiver operating characteristic (ROC) curves with Youden J-statistic and cross-validation of regression models assessed the ability of these measures to predict surgery. RESULTS: A total of 212 patients were included, consisting of 78 MCS, 37 MR, and 97 controls. Both the mean SNS angle (MCS: 111.7 ± 10.7 degrees, MR: 126.0 ± 8.2 degrees, controls: 130.7 ± 8.8 degrees P < 0.001) and MSS (MCS: 5.9 ± 2.0, MR: 1.4 ± 1.9, controls: 0.2 ± 1.9, P < 0.001) were different among the cohorts. The mean SNS angle (111.5 ± 10.7 versus 129.1 ± 8.8, P < 0.001) was lower in those who had surgery and CranioRate score (5.9 ± 2.1 versus 0.8 ± 2.2, P < 0.001) was higher in those who underwent surgery. SNS angles were positively correlated with surgeon craniofacial dysmorphology rankings ( r = 0.41, P < 0.05) and CranioRate MSS ( r = 0.54, P < 0.05). The ROC curve requiring high sensitivity revealed an SNS angle of 124.8 degrees predicted surgery with a sensitivity of 88.7% and a specificity of 71.3%. A ROC curve using the CranioRate MCC values ≥3.19 predicted surgery with 88.7% sensitivity and 94.7% specificity. CONCLUSION: Orbital dysmorphology in patients with MCS is well captured by the supraorbital-nasion angle. Both the SNS angle and CranioRate MSS scores accurately predict surgical intervention.

Orbital doppler ultrasound as an ancillary test for diagnosing brain death: A prospective, single blind comparative study.

OBJECTIVE: Transcranial Doppler ultrasound (TDUS), computed tomography angiography (CTA), and transcranial Doppler ultrasound to detect cerebral blood flow are among the adjunctive tests in diagnosing brain death. This study aimed to investigate the effectiveness of orbital doppler ultrasound (ODUS). METHODS: This prospective, single-blind study included 66 patients for whom brain death was to be diagnosed. Primary outcome measures were ODUS measurements, Ophthalmic artery peak systolic velocity (PSV), end-diastolic velocity (EDV), and resistive indices (RI) measurements recorded during the brain death determination process. Secondary outcome measures were computed tomography angio (CTA), transcranial Doppler ultrasound (TDUS), and demographic data. RESULTS: This study investigating the effectiveness of ODUS in diagnosing brain death provided diagnostic success with 100% sensitivity and 93% specificity compared to CT angiography. It was noted that anatomical variations may limit its use. CONCLUSION: ODUS was found to have high sensitivity and specificity in the diagnosis of clinical brain death. It may assist in early prognostic assessment and shorten patient follow-up and diagnostic processes.

Orbital Cerebrospinal Fluid Leak After Dog Bite: A Case Report

A 4-year-old boy was referred to our tertiary hospital after a penetrating adnexal injury by a large-breed dog to the left orbital area. There was an increase in lacrimation, which was thought to be due to an inflammatory reaction. However, it was discovered that the lacrimation increased in the reverse-Trendelenburg position and with the Valsalva maneuver. Halo sign and beta transferrin test were positive, which led to the diagnosis of cerebrospinal fluid (CSF) fistula, and the patient was operated using a supraorbital craniotomy. A dural tear was visualized and sutured appropriately, then fibrin glue and an autologous galeal graft were applied to the tear. The CSF oculorrhea stopped postoperatively, and the patient was discharged after 10 days of follow-up. The patient had no recurrent CSF leakage at 4-year follow-up. Although CSF oculorrhea is rare and may be difficult to discern from lacrimation, the presence of pneumocephalus and halo sign should suggest fistula repair.

Deep-Learning Based Automated Segmentation and Quantitative Volumetric Analysis of Orbital Muscle and Fat for Diagnosis of Thyroid Eye Disease.

Purpose: Thyroid eye disease (TED) is characterized by proliferation of orbital tissues and complicated by compressive optic neuropathy (CON). This study aims to utilize a deep-learning (DL)-based automated segmentation model to segment orbital muscle and fat volumes on computed tomography (CT) images and provide quantitative volumetric data and a machine learning (ML)-based classifier to distinguish between TED and TED with CON. Methods: Subjects with TED who underwent clinical evaluation and orbital CT imaging were included. Patients with clinical features of CON were classified as having severe TED, and those without were classified as having mild TED. Normal subjects were used for controls. A U-Net DL-model was used for automatic segmentation of orbital muscle and fat volumes from orbital CTs, and ensemble of Random Forest Classifiers were used for volumetric analysis of muscle and fat. Results: Two hundred eighty-one subjects were included in this study. Automatic segmentation of orbital tissues was performed. Dice coefficient was recorded to be 0.902 and 0.921 for muscle and fat volumes, respectively. Muscle volumes among normal, mild, and severe TED were found to be statistically different. A classification model utilizing volume data and limited patient data had an accuracy of 0.838 and an area under the curve (AUC) of 0.929 in predicting normal, mild TED, and severe TED. Conclusions: DL-based automated segmentation of orbital images for patients with TED was found to be accurate and efficient. An ML-based classification model using volumetrics and metadata led to high diagnostic accuracy in distinguishing TED and TED with CON. By enabling rapid and precise volumetric assessment, this may be a useful tool in future clinical studies.

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

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

Correlation of clinical and radiological scores for evaluation of activity in patients having thyroid-associated orbitopathy: A prospective observational study.

PURPOSE: To find a correlation between the clinical (vision-inflammation-strabismus-appearance [VISA] score) and radiological (apparent diffusion coefficient [ADC] values) scores for evaluating disease activity in patients with thyroid-associated orbitopathy. DESIGN: A prospective comparative study. METHODS: Our study was performed for consecutively diagnosed thyroid-associated orbitopathy (TAO) patients. Clinical evaluation included the VISA classification system with the basic thyroid workup. An inflammatory score of <4/8 was considered inactive and ≥4/8 as an active disease. Every included patient underwent a diffusion-weighted magnetic resonance imaging (DW-MRI) scan of the orbits. The orbital parameters evaluated on imaging included the proptosis, thickness, as well as the ADC values of extraocular muscles. RESULTS: We studied 33 consecutive patients (23 females, 69.7%) with a mean age of 41.8 years. The majority (n = 27, 81.8%) were hyperthyroid, four were hypothyroid, and two were euthyroid. In the VISA classification, nine patients had active TAO (≥4/8 inflammation score), while 24 had inactive disease. There was a positive correlation between the inflammation score and ADC values of medial rectus (MR), inferior rectus (IR) and lateral rectus (LR). We had nine patients with inflammation scores ≥4. With receiver operating characteristic (ROC) curve analysis, we found that the ADC value of IR can predict disease activity with 68% sensitivity and MR-ADC can predict active TAO with 87% sensitivity. CONCLUSION: The ADC parameters of DW-MRI are objective and less operator dependent than the clinical TAO activity scores like VISA classification. A randomized control trial may provide robust data on this correlation.

Emergency surgical decompression of the orbit may rescue impaired vision even in a patient presenting late with a retrobulbar haematoma: A case report from rural southwestern Uganda.

Retrobulbar haematoma is a rare emergency that can potentially lead to blindness. Common causes include facial trauma and surgery. Timely surgical evacuation of the haematoma improves visual outcomes. In rural communities, patients often present to hospital after many hours and this increases the risk of poor visual outcomes. Radiological evaluation which is often not available in rural communities, results in further delay in surgical treatment. This case report highlights the need for urgent surgical intervention over radiological evaluation in patients with retrobulbar haematoma and orbital compartment syndrome.

Primary intraorbital inflammatory lumpy lesion: A rare case report.

RATIONALE: Eosinophilic angiocentric fibrosis (EAF) is considered to be a kind of benign IgG4-related disease, and it is more often found in the nasal cavity. We present a pretty rare case of orbital EAF that is unlike any other reported case for this case is an IgG4 negative orbital EAF and successfully treated by the fronto orbitozygomatic approach surgery. PATIENT CONCERNS: This is a 68-year-old man from a rural area of Inner Mongolia Autonomous Region, went to our hospital for a 2-month history of vision loss with a local hospital orbital computer tomography which showed that there was a lesion in his left orbit. The inspection of the patient revealed that the patient left eye was protruding outward and the left eyelid unable to complete open or close. And his left eyeball movement had difficulty in all directions. Postoperative pathology diagnosed that this was a case of IgG4-negative EAF case. DIAGNOSES: Orbital EAF. INTERVENTIONS: Surgical radical resection and postoperative glucocorticoid therapy. OUTCOMES: After surgery, the left eye vision of this patient increased to 0.6 tested in the standard logarithmic visual acuity chart. And his left eyeball movement dysfunction and eyeball outward protruding get a partially relief. LESSONS: EAF occurring in the orbit is a very rare disease and immunohistochemical results of EAF can be IgG4 negative.

Normative measurements of orbital structures on magnetic resonance images; a cross-sectional study with mini review of the literature.

PURPOSE: Awareness of normative values of extra orbital structures would provide useful information to interpret the radiological images better and use them for diagnostic purposes. This study aimed to reveal the average values of major extraocular structures measured on magnetic resonance images. METHODS: In this retrospective cross-sectional study, magnetic resonance (MR) images of 256 orbits of 128 patients were re-interpreted regarding the measurements of major orbital structures. Extraocular muscles, superior ophthalmic vein, and optic nerve-sheath complex were measured on orbital MR images of these patients. The data distributions were presented by box-plot analyses for each parameter, and the measurement results were analyzed regarding gender and age groups. RESULTS: Lateral rectus muscle thickness (LR), inferior rectus muscle thickness (IR), globe position (GP), and interzygomatic line (IZL) values were higher in the male group than in the female group (p values were < 0.001, 0.003, 0.020, and < 0.001 respectively). LR, the thickness of the superior group muscles (SUP GR), IR, superior oblique muscle thickness (SOBL), and the thickness of optic nerve-sheath complex (ON) values indicated a significant relationship between age groups. There was a significant, positive, and low-level correlation between age and LR, SUP GR, and IR values (p values were < 0.001, 0.001, and < 0.001, respectively). CONCLUSION: This study provides quantitative data on normative values of orbital structures with gender and age group comparisons. Clinicians or surgeons can easily use the measured values to gather diagnostic information from the orbital region.

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.

Biological identity of orbital cavernous venous malformations.

Vascular anomalies comprise a wide spectrum of clinical manifestations related to disturbances in the blood or lymph vessels. They correspond to mainly tumors (especially hemangiomas), characterized by high mitotic activity and proliferation of the vascular endothelium, and malformations, endowed with normal mitotic activity and no hypercellularity or changes in the rate of cell turnover. However, the classifications of these lesions go beyond this dichotomy and consist various systems adapted for and by different clinical subgroups. Thus, the classifications have not reached a consensus and have historically caused confusion regarding the nomenclatures and definitions. Cavernous venous malformations of the orbit, previously called cavernous hemangiomas, are the most common benign vascular orbital lesions in adults. Herein, we have compiled and discussed the various evidences, including clinical, radiological, morphological, and molecular evidence that indicate the non-neoplastic nature of these lesions.

Ultrasound-Based Predictive Model to Assess the Risk of Orbital Malignancies.

OBJECTIVE: Ultrasound (US) is widely used for evaluating various orbital conditions. However, accurately diagnosing malignant orbital masses using US remains challenging. We aimed to develop an ultrasonic feature-based model to predict the presence of malignant tumors in the orbit. METHODS: A total of 510 patients with orbital masses were enrolled between January 2017 and April 2023. They were divided into a development cohort and a validation cohort. In the development cohort (n = 408), the ultrasonic and clinical features with differential values were identified. Based on these features, a predictive model and nomogram were constructed. The diagnostic performance of the model was compared with that of MRI or observers, and further validated in the validation cohort (n = 102). RESULTS: The involvement of more than two quadrants, irregular shape, extremely low echo of the solid part, presence of echogenic foci, cast-like appearance, and two demographic characteristics (age and sex) were identified as independent features related to malignant tumors of the orbit. The predictive model constructed based on these features exhibited better performance in identifying malignant tumors compared to MRI (AUC = 0.78 [95% CI: 0.73, 0.82] vs. 0.69 [95% CI: 0.64, 0.74], p = 0.03) and observers (AUC = 0.93 [95% CI: 0.90, 0.95] vs. Observer 1, AUC = 0.80 [95% CI: 0.76, 0.84], p < 0.01; vs. Observer 2, AUC = 0.71 [95% CI: 0.66, 0.76], p < 0.01). In the validation cohort, the predictive model achieved an AUC of 0.88 (95% CI: 0.81, 0.94). CONCLUSION: The ultrasonic-clinical feature-based predictive model can accurately identify malignant orbital tumors, offering a convenient approach in clinical practice.

Image-guided orbital surgery: a preclinical validation study using a high-resolution physical model.

OBJECTIVE: Preclinical validation study to assess the feasibility and accuracy of electromagnetic image-guided systems (EM-IGS) in orbital surgery using high-fidelity physical orbital anatomy simulators. METHODS: EM-IGS platform, clinical software, navigation instruments and reference system (StealthStation S8, Medtronic) were evaluated in a mock operating theatre at the Royal Victoria Eye and Ear Hospital, a tertiary academic hospital in Dublin, Ireland. Five high-resolution 3D-printed model skulls were created using CT scans of five anonymised patients with an orbital tumour that previously had a successful orbital biopsy or excision. The ability of ophthalmic surgeons to achieve satisfactory system registration in each model was assessed. Subsequently, navigational accuracy was recorded using defined anatomical landmarks as ground truth. Qualitative feedback on the system was also attained. RESULTS: Three independent surgeons participated in the study, one junior trainee, one fellow and one consultant. Across models, more senior participants were able to achieve a smaller system-generated registration error in a fewer number of attempts. When assessing navigational accuracy, submillimetre accuracy was achieved for the majority of points (16 landmarks per model, per participant). Qualitative surgeon feedback suggested acceptability of the technology, although interference from mobile phones near the operative field was noted. CONCLUSION: This study suggests the feasibility and accuracy of EM-IGS in a preclinical validation study for orbital surgery using patient specific 3D-printed skulls. This preclinical study provides the foundation for clinical studies to explore the safety and effectiveness of this technology.

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.

Clinical Relevance of the Variability of the Infraorbital Arterial Anatomy Evaluated by Three-Dimensional Computed Tomography.

BACKGROUND: Knowledge of the anatomy of the infraorbital artery (IOA) is crucial for the rejuvenation of the anterior medial aspect of the midface; however, studies adequately describing the anatomy of the IOA branches are lacking, and their connection with the ophthalmic artery branches remains unclear. OBJECTIVES: This study aims to elucidate the anatomical characteristics of the IOA in its deployment within the lower eyelid using three-dimensional (3D) technology, thereby offering an anatomical foundation for clinical surgical procedures. METHODS: An analysis was conducted on computed tomography scans of 132 cadaveric head sides post-contrast injection, utilizing the Mimics software for reconstruction. The study focused on examining the anastomosis of the IOA, its principal branches, and the branches emanating from the ophthalmic artery. RESULTS: The prevalence of type I IOA was observed at 38.6% (51/132), while Type II IOA was found in 61.4% (81/132) of cases. A 7.6% incidence (10/132) of IOA directly anastomosing with the angular artery was noted. The presence of palpebral branches (PIOA) was identified in 57.6% (76/132) of instances. In the lower eyelid, four distinct distribution patterns of IOA were discerned: The likelihood of Type I PIOA was 5.3%, whereas for Types IIA, IIB, and IIC PIOA, the probabilities were 8.3%, 32.6%, and 11.4%, respectively. The occurrence of the orbital branch of IOA was recorded at 41.7% (55/132). CONCLUSIONS: 3D technology can map IOA variants and identify the deployment patterns of IOA branches in the lower eyelid vascular vesicles at high resolution as a guide in clinical practice. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .