Artificial intelligence to automate assessment of ocular and periocular measurements.

PURPOSE: To develop and validate a deep learning facial landmark detection network to automate the assessment of periocular anthropometric measurements. METHODS: Patients presenting to the ophthalmology clinic were prospectively enrolled and had their images taken using a standardised protocol. Facial landmarks were segmented on the images to enable calculation of marginal reflex distance (MRD) 1 and 2, palpebral fissure height (PFH), inner intercanthal distance (IICD), outer intercanthal distance (OICD), interpupillary distance (IPD) and horizontal palpebral aperture (HPA). These manual segmentations were used to train a machine learning algorithm to automatically detect facial landmarks and calculate these measurements. The main outcomes were the mean absolute error and intraclass correlation coefficient. RESULTS: A total of 958 eyes from 479 participants were included. The testing set consisted of 290 eyes from 145 patients. The AI algorithm demonstrated close agreement with human measurements, with mean absolute errors ranging from 0.22 mm for IPD to 0.88 mm for IICD. The intraclass correlation coefficients indicated excellent reliability (ICC > 0.90) for MRD1, MRD2, PFH, OICD, IICD, and IPD, while HPA showed good reliability (ICC 0.84). The landmark detection model was highly accurate and achieved a mean error rate of 0.51% and failure rate at 0.1 of 0%. CONCLUSION: The automated facial landmark detection network provided accurate and reliable periocular measurements. This may help increase the objectivity of periocular measurements in the clinic and may facilitate remote assessment of patients with tele-health.

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.

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.

Radiological measurements of lacrimal gland in thyroid eye disease.

PURPOSE: Lacrimal gland enlargement is a common feature of thyroid eye disease (TED) and has been positively correlated with the clinical activity score. Although lacrimal gland volume is the preferred measure of lacrimal gland size, its calculation is not clinically translatable due to the expertise, time and advanced software required. The aim of our study is to determine whether the lacrimal gland volume in patients with TED undergoing magnetic resonance imaging (MRI) can be estimated using simpler lacrimal gland linear and area measurements. METHODS: A retrospective review of 102 orbits (51 patients) with TED who underwent orbital MRI was conducted. The maximum length, width, and area of the lacrimal gland were measured in axial and coronal sections. Lacrimal gland volume was calculated by using a manual segmentation technique on all consecutive axial slices on commercially available software, OsiriX. All quantitative measurements were correlated with the lacrimal gland volume. RESULTS: Mean age of participants was 59 ± 16 years, and 67% (n = 34) were females. With multivariate analyses, combined lacrimal gland axial and coronal areas strongly correlated with volume (r = 0.843, p < 0.01). Strong univariate predictors of volume included axial area (r = 0.704, p < 0.01) and coronal area (r = 0.722, p < 0.01), while moderate predictors included axial length (r = 0.523, p < 0.01), axial width (r = 0.521, p < 0.01), coronal length (r = 0.450, p < 0.01), and coronal width (r = 0.649, p < 0.01). CONCLUSION: In patients with thyroid eye disease, lacrimal gland volume can be estimated using axial and coronal areas, which is simpler and more time efficient than calculating volumes.

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.

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.

A novel case of recurrent cylindroma of the orbit.

Cylindroma is a rare benign tumour of eccrine origin that has not been previously reported within the orbit. We report a case of a recurrent orbital cylindroma following incomplete excision. A 75-year-old female presented with a recurrent left inferomedial orbital mass. Seven years prior a mass of the same location was excised and on histology at the time resembled a cylindroma. The patient had a history of lung adenocarcinoma. Magnetic resonance imaging (MRI) found the recurrent mass to be a well-circumscribed lesion anterior to the inferior oblique. The mass was subsequently excised. Histological analysis found a well-circumscribed neoplasm with a characteristic jigsaw pattern of nested cells, consistent with cylindroma. This case demonstrates the possibility for cylindromas to occur within the orbit and their ability to reoccur if incompletely excised.

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.

Normal periocular anthropometric measurements in an Australian population.

PURPOSE: To report the normative ocular and periocular anthropometric measurements in an Australian cohort and investigate how these may be affected age, gender, and ethnicity. METHODS: Prospective study of patients presenting to the Royal Adelaide Hospital. Patient with orbital or eyelid disease, previous surgery, craniofacial abnormalities, pupil abnormalities, strabismus, and poor image quality was excluded. Standardised photographs were taken in a well-illuminated room. A green dot with a diameter of 24 mm was placed on the participant's foreheads for calibration between pixels and millimetres. Ocular and periocular landmarks were segmented to calculate the periorbital measurements. Independent sample t test was used to compare male and female subjects, Pearson's correlation was used to correlate periocular dimensions with age, and ANOVA with Bonferroni was used to compare periocular dimension between ethnic groups. RESULTS: Seven hundred and sixty eyes from 380 participants (215 female, mean age 58 ± 18 years) were included. The mean marginal reflex distance (MRD) 1 was 3.5 mm and decreased with increasing age (r = - 0.09, p = 0.01) and MRD 2 was 5.2 mm. Compared to Caucasians, African subjects had a significantly larger interpupillary distance and outer intercanthal distance, whereas East Asians had a significantly larger inner intercanthal distance (p < 0.05). The values of marginal reflex distance 2, palpebral fissure height, horizontal palpebral aperture, inner intercanthal distance, interpupillary distance and outer intercanthal distance were significantly higher in male subjects than female subjects (p < 0.05). CONCLUSIONS: Normative periocular dimensions may vary according to age, gender, and ethnicity. An understanding of normal periocular dimensions is important in the evaluation of orbital disease across different ethnic groups and may serve as reference points for oculoplastic surgery and industry.

Normative orbital measurements in an Australian cohort on computed tomography.

PURPOSE: To determine the normal diameters of the extraocular muscles (EOMs) and optic nerve sheath complex (ONSD) and correlate with patient demographics in an Australian cohort. METHODS: Consecutive patients who underwent contrast enhanced computed tomography (CT) orbits between December 2017 and March 2021 were included. Patients with bilateral disease, previous orbital surgery, or poor scan quality were excluded. Normal orbit was used in patients with unilateral orbital disease. RESULTS: Two hundred one orbits from 201 patients were included. Normal measurements (mean ± SD) were as follows: medial rectus (MR) 4.22 ± 0.56 mm; inferior rectus (IR) 4.20 ± 0.70 mm; lateral rectus (LR) 3.40 ± 0.56 mm; superior muscle group (SMG) 4.13 ± 0.72 mm; superior oblique (SO) 2.60 ± 0.43 mm; inferior oblique (IO) on quasi-sagittal plane 2.19 ± 0.42 mm, and the ONSD 5.62 ± 0.82 mm. The mean diameters of the LR, SMG, IR, SO, and ONSD were significantly larger in male than female patients (p < .05). Statistically significant correlation was found between age and the diameters of the LR (r = 0.29, p < .01), SMG (r = 0.22, p < .01), IO on a coronal plane (r = -0.18, p < .01), and ONSD (r = 0.16, p = .02). CONCLUSION: This normative data may be used to diagnose pathological enlargement of the optic nerve and extraocular muscles, including involvement of the oblique muscles.

Normative lacrimal gland dimensions by magnetic resonance imaging in an Australian cohort.

PURPOSE: To report the normative dimensions of the lacrimal gland on fat-suppressed contrast-enhanced magnetic resonance imaging (MRI) in an Australian cohort. METHODS: Retrospective review of patients who underwent 3 T orbital MRI is presented. Two hundred eleven orbits were used to conduct lacrimal gland measurements. Orbits were excluded if there was ipsilateral orbital or lacrimal gland disease, prior surgery, or poor image quality. The length and width of the lacrimal gland were measured in axial and coronal sections using the largest image. RESULTS: The mean lacrimal gland axial length was 14.6 mm in the right orbit and 14.3 mm in the left orbit. The mean axial width was 4.9 mm in both orbits. Coronal lengths averaged 16.2 mm in the right orbit and 16.4 mm in the left orbit. The coronal width averaged 4.8 mm in both orbits. A significant negative correlation was found between age and the right axial length (r = -0.26, p < .01) and the left axial length (r = -0.26, p < .01) of the lacrimal gland. No statistically significant difference was found between genders or laterality. CONCLUSION: This study presents the normal lacrimal gland dimensions on fat-suppressed contrast-enhanced MRI in an Australian cohort. An inverse relationship exists between age and the axial length of the lacrimal gland. These data may be used to help diagnose enlargement of the lacrimal gland.

Normative globe position values on orbital computed tomography in Australians.

OBJECTIVE: To determine normal globe position values, interzygomatic distance (IZD), and globe axial length and width on computed tomography in an Australian cohort. DESIGN: Retrospective cohort study. PARTICIPANTS: Patients who underwent computed tomography of the orbits. Patients with bilateral disease, previous orbital surgery, or poor scan quality were excluded. METHODS: An axial slice through the midglobe was used to conduct the globe position measurements. Anterior globe position was defined as the perpendicular distance from the anterior globe margin to the interzygomatic line and posterior globe position as the perpendicular distance from the posterior globe margin to the interzygomatic line. RESULTS: The normal measurements (mean ± SD) were IZD, 97.4 ± 4.1 mm; anterior globe position, 18.8 ± 2.8 mm; posterior globe position, 6.2 ± 2.9 mm; axial globe length, 24.9 ± 1.1 mm; and axial globe width, 25.9 ± 1.2 mm. A significant positive correlation was seen between the IZD and the anterior globe position (r = 0.15, p = 0.03), axial globe length (r = 0.33, p < 0.01), and axial globe width (r = 0.30, p < 0.01). CONCLUSION: This normative globe position data may be used to diagnose radiologic exophthalmos or enophthalmos.

Normative measurements of orbital structures by magnetic resonance imaging.

PURPOSE: We describe and compare the normative values of orbital structures in an Australian cohort on T1-weighted MRI and fat-suppressed contrast-enhanced T1-weighted MRI. METHODS: Retrospective review of patients who underwent 3T orbital MRI. The maximum extraocular muscle (EOM) and superior ophthalmic vein (SOV) diameters on normal orbits were recorded. The extraocular muscle diameters were summed to produce the sum of all muscles. RESULTS: The normal measurements (mean ± SD) from 141 orbits that had fat-suppressed contrast-enhanced MRI: medial rectus, 4.1 ± 0.5 mm; lateral rectus (LR), 3.9 ± 0.7 mm; superior muscle group (SMG), 4.5 ± 0.7 mm; inferior rectus (IR), 4.6 ± 0.7 mm; and SOV, 1.8 ± 0.7 mm. The normal measurement from 84 orbits that had T1-weighted MRI: MR, 4.1 ± 0.5 mm; LR, 3.4 ± 0.6 mm; SMG, 4.3 ± 0.7 mm; IR, 4.6 ± 0.7 mm; SOV, 2.0 ± 0.7 mm. Eighty-four orbits had both MRI sequences performed. The LR, SMG and the sum of all muscles were significantly larger on fat-suppressed contrast-enhanced T1-weighted MRI sequence than the T1-weighted sequence (P < 0.01), whereas the SOV was significantly larger on the T1-weighted sequence (P < 0.01). CONCLUSION: These data may aid in diagnosing pathological enlargement of the EOMs and SOV on different scan sequences.

Extraocular muscle enlargement.

Extraocular muscle enlargement can occur secondary to a range of orbital and systemic diseases. Although the most common cause of extraocular muscle enlargement is thyroid eye disease, a range of other inflammatory, infective, neoplastic, and vascular conditions can alter the size and shape of the extraocular muscles. Imaging with computed tomography and magnetic resonance imaging plays an essential role in the workup of these conditions. This article provides an image-rich review of the wide range of pathology that can cause enlargement of the extraocular muscles.

Normative measurements of the superior oblique and inferior oblique muscles by magnetic resonance imaging.

PURPOSE: Normative oblique muscle data may help to diagnose pathological enlargement of the oblique muscles. We aim to describe the normative values of the superior and inferior oblique muscles in an Australian cohort on T1-weighted MRI and fat suppressed contrast enhanced T1-weighted MRI. METHODS: A retrospective review of patients who underwent 3 T orbital MRI. The healthy orbits were used to conduct measurements in patients with a unilateral orbital lesion. The maximum diameters of the superior and inferior oblique muscles were measured on coronal planes. The diameter was measured perpendicular to the long axis of the muscles. RESULTS: The normal measurements (mean ± SD) on fat suppressed contrast enhanced T1-weighted MRI: superior oblique, 3.0 ± 0.5 mm and inferior oblique, 2.7 ± 0.5 mm. On T1-weighted MRI: superior oblique, 2.8 ± 0.5 mm and inferior oblique, 2.5 ± 0.4 mm. In patients who had both sequences performed, the superior and inferior oblique diameters were significantly higher on the fat suppressed contrast-enhanced T1-weighted MRI than the T1-weighted MRI sequence (p < 0.01). CONCLUSION: Oblique muscle enlargement may be seen in a range of orbital diseases. These data may help in diagnosing oblique muscle enlargement. In addition, variations in the measured muscle diameters can be seen according to the scan sequence that is used.