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Fractures of the walls of the orbit can cause a number of problems which include diplopia, extraocular muscle entrapment, enophthalmos, etc. Medial wall fractures are the most common among all orbital wall fractures, and their anatomical reconstruction is relatively challenging. Various autogenous and synthetic materials have been tried over the years, and each has its own advantages and limitations. In this case report, a 17-year-old male presented with an outward deviation of his left eye with binocular double vision since 18 days following a blunt injury with a tennis ball. He was diagnosed with a trapdoor fracture of the medial wall of the left orbit with entrapment of medial rectus muscle which was successfully managed by releasing the entrapped muscle and reconstructing the defect using an intraoral periapical X-ray film. [ABSTRACT FROM AUTHOR]

Cysticercosis, a zoonotic disease caused by Taenia species parasites, can manifest in various clinical presentations, including orbital involvement. Extraocular orbital cysticercosis commonly affects the superior muscle complex and recti, often resembling subacute orbital myositis. Our case of a six-year-old boy underscores the importance of recognizing this condition. He presented with pain, redness, swelling and ptosis, leading to a diagnostic journey involving ocular examination, imaging and investigations. Treatment with oral steroids and anthelminthic medication was initiated, with clinical improvement upon regular follow-up. This case highlights the challenge of differentiating cysticercosis from other orbital pathologies and underscores the significance of prompt diagnosis and management to prevent ocular morbidity.

Background: This study aims to determine the normal values of orbital structures according to sex in healthy adults. Methods: Diameters of extraocular muscles, the width of the optic nerve sheath diameter, the length of the inter-zygomatic line, ocular bulb length, and globe position were measured in the T1-weighed MR (magnetic resonance) images in 204 orbits of 102 individuals. Results: The mean values of the diameters of the extraocular muscles in males and females were as follows: medial rectus, 3.96 ± 0.52 and 3.58 ± 0.53 mm; lateral rectus, 3.47 ± 0.61 and 3.15 ± 0.48 mm; inferior rectus, 4.47 ± 0.53 and 4.07 ± 0.48 mm; superior rectus, 4.44 ± 0.64 and 4.01 ± 0.56 mm; and superior oblique, 3.68 ± 0.49 and 3.45 ± 0.44 mm. The length of the interzygomatic line in males and females were 102.68 ± 3.89 and 96.95 ± 3.4 mm, the ocular bulb length was 23.33 ± 1.32 and 22.83 ± 1.1 mm, the globe position was 7.66 ± 1.33 and 7.3 ± 1.39 mm, and the width of the optic nerve sheath diameter was 4.65 ± 0.62 and 4.28 ± 0.51 mm, respectively. All measurements were significantly greater for males than for females (p < 0.05). Conclusions: We believe that a practical and quantitative method will be provided by this study for the diagnosis and determination of the normative values of orbital structures.

With the development of strabismology, the issues of using Botox in various eye movement pathologies are gaining relevance. The literature analysis shows that the data concerning the effectiveness of Botox are ambivalent and as a rule, are based on short-term results. The review presents the data on the efficiency of the botulinum toxin in the treatment of various oculomotor system diseases in comparison with traditional surgical interventions. Indications for such therapy, application techniques, doses and complications are discussed. The generalized modern data on the functional features of the onset of various pathologies in strabismology help assess the potentials of optimizing strabismus treatment with type A botulinum toxin. To search for the data published between 1973 and 2022, select and summarize them we used Google Scholar, PubMed and eLibrary databases.

Yuji Yamana,1 Tomoyuki Kashima,1 Masashi Mimura1– 3 1Department of Ophthalmology, Oculofacial Clinic Group, Tokyo, Japan; 2Department of Ophthalmology, Hyogo Medical University, Nishinomiya, Japan; 3Department of Ophthalmology, Toho University Sakura Medical Center, Sakura, JapanCorrespondence: Yuji Yamana, Oculofacial Clinic, Tokyo, Japan, Email yuzi.yamana@gmail.comPurpose: Orbital steroid injections offer a potential therapeutic avenue for managing Thyroid Eye Disease (TED). This study aimed to assess the effectiveness and potential systemic impacts of a single deep orbital triamcinolone injection in TED patients.Methods: In a prospective investigation conducted from January 2021 to March 2023, patients diagnosed with TED were enrolled. Inclusion criteria encompassed a Clinical Activity Score (CAS) of ≥ 3, extraocular muscle inflammation, and upper eyelid retraction. A total of 1 mL of triamcinolone acetonide (40 mg/mL) was administered posterior to the orbital septum at both the medial and lateral aspects of both the upper and lower eyelids. Parameters, including CAS, margin-reflex distances (MRD1 and MRD2), intraocular pressure (IOP), ocular motility (Hess area ratio [HAR%]), exophthalmometry, extraocular muscle size, and blood and urinary indices, were evaluated before and at 2 and 4 weeks after a single injection.Results: Analysis included 28 patients (23 women, 5 men; mean age (SD): 38.7 (11.1) years), representing 56 eyes. Following the injection at 4 weeks, the mean CAS and MRD1 significantly decreased by 2 points and 0.8 mm, respectively. There was a 4.5% increase in HAR%, and extraocular muscle size decreased by 4 to 15.3 mm². Neutrophil count, C-reactive protein, and thyroid antibodies significantly decreased. No severe adverse ophthalmic or systemic effects, including IOP increases or liver damage, were observed.Conclusion: Bilateral single orbital triamcinolone injections provided relief from TED symptoms through both direct effects on orbital soft tissue and systemic effects by decreasing antibody reactions.Keywords: thyroid eye disease, orbital steroid injections, triamcinolone, extraocular muscles

Background: This study aims to determine the normal values of orbital structures according to sex in healthy adults. Methods: Diameters of extraocular muscles, the width of the optic nerve sheath diameter, the length of the inter-zygomatic line, ocular bulb length, and globe position were measured in the T1-weighed MR (magnetic resonance) images in 204 orbits of 102 individuals. Results: The mean values of the diameters of the extraocular muscles in males and females were as follows: medial rectus, 3.96 ± 0.52 and 3.58 ± 0.53 mm; lateral rectus, 3.47 ± 0.61 and 3.15 ± 0.48 mm; inferior rectus, 4.47 ± 0.53 and 4.07 ± 0.48 mm; superior rectus, 4.44 ± 0.64 and 4.01 ± 0.56 mm; and superior oblique, 3.68 ± 0.49 and 3.45 ± 0.44 mm. The length of the interzygomatic line in males and females were 102.68 ± 3.89 and 96.95 ± 3.4 mm, the ocular bulb length was 23.33 ± 1.32 and 22.83 ± 1.1 mm, the globe position was 7.66 ± 1.33 and 7.3 ± 1.39 mm, and the width of the optic nerve sheath diameter was 4.65 ± 0.62 and 4.28 ± 0.51 mm, respectively. All measurements were significantly greater for males than for females (p < 0.05). Conclusions: We believe that a practical and quantitative method will be provided by this study for the diagnosis and determination of the normative values of orbital structures. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the alterations in extraocular muscles (EOMs) by magnetic resonance imaging (MRI) among patients diagnosed with Duane retraction yndrome (DRS) and congenital fibrosis of the extraocular muscles (CFEOM), who present with various cranial nerve anomalies in an attempt to enhance the clinical diagnostic process. Methods: A case–control study was conducted to evaluate 27 patients with DRS and 14 patients with CFEOM. All patients underwent MRI scans of the brainstem and orbital examination. Neurodevelopmental assessments were conducted through MRI, and maximum cross-sectional area and volumes of EOMs were obtained. Three types of models were constructed using machine learning decision tree algorithms based on EOMs to predict disease diagnosis, cranial nerve abnormalities, and clinical subtypes. Results: Patients with bilateral CN VI abnormalities had smaller volumes of LR, MR, and IR muscles compared to those with unilateral involvement (P < 0.05). Similarly, patients with CFEOM and unilateral third cranial nerve abnormalities had a smaller maximum cross-section of the affected eye's SR compared to the contralateral eye (P < 0.05). In patients with both CN III and CN VI abnormalities, the volume of SR was smaller than in patients with CN III abnormalities alone (P < 0.05). The prediction model using EOMs volume showed a diagnostic precision of 82.5% for clinical cases and 60.1% for predicting cranial nerve abnormalities. Nonetheless, the precision for identifying clinical subtypes was relatively modest, at only 41.7%. Conclusion: The distinctive volumetric alterations in EOMs among individuals exhibiting distinct cranial nerve anomalies associated with DRS or CFEOM provide valuable diagnostic insights into to Congenital Cranial Neurodevelopmental Disorders (CCDDs). MRI analysis of EOMs should thus be regarded as a crucial diagnostic modality. [ABSTRACT FROM AUTHOR]

Background: The dysregulation of extraocular muscles (EOMs) in the strabismus may be partly due to modification in the mitochondrial DNA (mtDNA). Currently, little is known about changes occurring in mtDNA of EOMs in patients with strabismus, therefore the aim of our study was to analyze if there are any changes occurring in the mitochondrial DNA of extraocular muscles in children that underwent strabismus surgery in our clinic. Methods: MtDNA was isolated from the tissue material using the Qiagen kit. Assessment of mtDNA mutations was performed by next-generation sequencing (NGS) using the Illumina MiSeq protocol. Results: The examination revealed the presence of atrophic changes in muscle fibers. NGS evaluation revealed a dominant genetic mutation in the ANT1 gene in 12 of the 15 patients examined. Conclusions: The presented results constitute the beginning of research on changes in mtDNA occurring in the muscles of children with strabismus surgery. Further studies are necessary in the context of resolving the transcriptomic differences between strabismic and non-strabismic EOMs. Better understanding of the molecular genetics of strabismus will lead to improved knowledge of the disease mechanisms and ultimately to a more effective treatment. [ABSTRACT FROM AUTHOR]

The extraocular muscles (EOMs) possess unique characteristics that set them apart from other skeletal muscles. These muscles, responsible for eye movements, exhibit remarkable resistance to various muscular dystrophies and aging, presenting a significant contrast to the vulnerability of skeletal muscles to these conditions. In this review, we delve into the cellular and molecular underpinnings of the distinct properties of EOMs. We explore their structural complexity, highlighting differences in fiber types, innervation patterns, and developmental origins. Notably, EOM fibers express a diverse array of myosin heavy-chain isoforms, retaining embryonic forms into adulthood. Moreover, their motor innervation is characterized by a high ratio of nerve fibers to muscle fibers and the presence of unique neuromuscular junctions. These features contribute to the specialized functions of EOMs, including rapid and precise eye movements. Understanding the mechanisms behind the resilience of EOMs to disease and aging may offer insights into potential therapeutic strategies for treating muscular dystrophies and myopathies affecting other skeletal muscles. [ABSTRACT FROM AUTHOR]

Introduction: Clinical manifestations of cranial nerve palsies are of great importance, and surgeons should consider them before planning surgical protocol. Materials and Methods: This retrospective study was conducted on preoperative hospital records of 598 Iranian patients with different types of extraocular muscle palsy, including third (90 patients), fourth (501 patients), and fifth (7 patients) nerve palsy at Farabi Hospital, Tehran Province, Iran. Results: In terms of fourth nerve palsy, the mean spherical equivalent (SE) in the right and left eye was 0.23±1.51 and 0.19±1.45 diopter, respectively. Also, the mean angle of vertical deviation was 15.54±8.85 Δ at near and 15.66±8.93 Δ at far. In patients with third nerve palsy, the mean SE in the right and left eye was -0.02±2.08 and 0.08±1.95 diopter, respectively. Also, the mean angle of vertical deviation was 17.8±17.4 Δ at near and 17.8±17.5 Δ at far. In terms of six nerve palsy, the mean SE in the right and left eye was -1.27±3.37 and -1.08±2.52 diopter, respectively. Also, the mean angle of esotropia was 32.4±7.7 Δ at near and 33±6.7 Δ at far. The frequency of amblyopia in patients with third, fourth, and sixth nerve palsies was 21 patients (23.3%), 70(14%), and 4(57.1%), respectively. Conclusion: The clinical characteristics of patients with different types of EOM palsy are remarkably different, which can be attributed to the different properties of these kinds of deviations. [ABSTRACT FROM AUTHOR]

To characterize the size of extraocular muscles (EOMs) in a pediatric population with thyroid dysfunction using orbital echography. Patients under age 18 with thyroid dysfunction who presented to an academic ophthalmology department from 2009 to 2020 and received orbital echography were included in this IRB-approved retrospective study. Data collected included age, clinical activity score (CAS), thyroid stimulating immunoglobulin (TSI), and extraocular recti muscle thickness on echography. Patients were organized into three age cohorts, after which statistical analysis compared recti measurements to previously reported normal ranges. Twenty patients with thyroid dysfunction were included. When comparing average recti muscle thicknesses of study patients to those of previously published normal children in similar age ranges, the levator-superior rectus complex was significantly increased in all age groups of children with thyroid dysfunction (p-values = <.004), and the levator-superior rectus complex was most frequently enlarged compared to published normal values (78% of eyes). CAS was not correlated with EOM size in the youngest group (5–10 years old, p-values >.315) but was significantly correlated in older groups (11–17 years old, p-values <.027). TSI was not correlated with EOM size in any group (p-values >.206). Echographic reference ranges for EOMs in children with thyroid dysfunction were established. There are increased rates of levator-superior rectus complex enlargement in children with TED compared to adults with TED, and EOM size is correlated with CAS in children older than 10 years. Though limited, these findings may serve as an additional tool for ophthalmologists to ascertain disease activity in pediatric patients with thyroid dysfunction. [ABSTRACT FROM AUTHOR]

Background: To retrospectively review lateral wall orbital decompression for thyroid eye disease (TED) and to evaluate pre-operative CT scans to analyse the variation in proptosis reduction. Methods: Consecutive lateral wall orbital decompressions performed by a single surgeon were retrospectively reviewed. Pre-operative CT scan features and post-operative proptosis reduction were analysed. The sphenoid trigone cross-sectional areas were summed and multiplied by the slice thickness to yield bone volume. Cumulative extraocular muscle thickness was calculated by combining the maximum thickness of the four recti. "Trigone volume" and "cumulative muscle thickness" were correlated with proptosis reduction at 3 months post-surgery. Results: Out of 73 consecutive lateral wall orbital decompressions, 17 orbits had prior endonasal medial wall orbital decompression. In the remaining 56 orbits, the mean pre-operative and post-operative proptosis were 24.3 ± 1.6 mm and 20.9 ± 2.3 mm respectively. The proptosis reduction ranged from 1 to 7 mm (mean of 3.5 mm ± 1.3 (p < 0.001)). Mean sphenoid trigone volume was 895 ± 434.4 mm3. The mean cumulative muscle thickness was 20.4 ± 5 mm. The correlation coefficient between muscle thickness and proptosis reduction was − 0.3 and was statistically significant (p = 0.043). The correlation coefficient between sphenoidal trigone volume and proptosis reduction was 0.2 (p = 0.068). With a multivariate analysis, the coefficient of efficient of regression for muscle thickness was − 0.007 (p = 0.42) and the coefficient of regression for trigone volume was 0.0 (p = 0.046). Conclusion: Proptosis reduction following lateral wall orbital decompression can be variable. Extraocular muscle thickness had a significant correlation with the outcome, with greater proptosis reduction in orbits with thin muscles. The sphenoidal trigone size had a weak correlation with decompression outcome. [ABSTRACT FROM AUTHOR]

AIM: To investigate the difference of medial rectus (MR) and lateral rectus (LR) between acute acquired concomitant esotropia (AACE) and the healthy controls (HCs) detected by magnetic resonance imaging (MRI). METHODS: A case-control study. Eighteen subjects with AACE and eighteen HCs were enrolled. MRI scanning data were conducted in target-controlled central gaze with a 3-Tesla magnetic resonance scanner. Extraocular muscles (EOMs) were scanned in contiguous image planes 2-mm thick spanning the EOM origins to the globe equator. To form posterior partial volumes (PPVs), the LR and MR cross-sections in the image planes 8, 10, 12, and 14 mm posterior to the globe were summed and multiplied by the 2-mm slice thickness. The data were classified according to the right eye, left eye, dominant eye, and non-dominant eye, and the differences in mean cross-sectional area, maximum cross-sectional area, and PPVs of the MR and LR muscle in the AACE group and HCs group were compared under the above classifications respectively. RESULTS: There were no significant differences between the two groups of demographic characteristics. The mean cross-sectional area of the LR muscle was significantly greater in the AACE group than that in the HCs group in the non-dominant eyes (P=0.028). The maximum cross-sectional area of the LR muscle both in the dominant and non-dominant eye of the AACE group was signi?cantly greater than the HCs group (P=0.009, P=0.016). For the dominant eye, the PPVs of the LR muscle were significantly greater in the AACE than that in the HCs group (P=0.013), but not in the MR muscle (P=0.698). CONCLUSION: The size and volume of muscles dominant eyes of AACE subjects change significantly to overcome binocular diplopia. The LR muscle become larger to compensate for the enhanced convergence in the AACE.

Rijo Hayashi,1 Shimmin Hayashi,1,2 Tomoharu Nishimura,1 Shigeki Machida1 1Department of Ophthalmology, Saitama Medical Center, Dokkyo Medical University, Koshigaya, Saitama, Japan; 2Lively Eye Clinic, Soka, Saitama, JapanCorrespondence: Rijo Hayashi, Department of Ophthalmology, Saitama Medical Center, Dokkyo Medical University, 2-1-50, Minamikoshigaya, Koshigaya, Saitama, 3438555, Japan, Tel/Fax +81-48-965-8659, Email lhayashi@dokkyomed.ac.jpPurpose: Acute acquired concomitant esotropia induced by excessive digital device usage, especially smartphones (SAACE), has been increasing over the past few years. Convergence spasm induced by excessive near work has been suggested as a mechanism. Anatomical differences could also potentially contribute to SAACE onset. The present study investigated the conformation of horizontal recti between SAACE patients and normal subjects.Patients and Methods: In 15 SAACE patients (SAACE group), the distances between the limbus and insertion of the horizontal recti (LI distance) and the widths of horizontal recti on the insertion (insertion width) were measured. The control group consisted of 30 patients who underwent retinal detachment surgery. Differences in LI distances and insertion widths were compared between SAACE and control groups.Results: While there were no differences between the two groups for LI distances and insertion widths of lateral recti, there were significantly shorter LI distances for the medial recti in the SAACE group (P< 0.05). Moreover, the SAACE group tended to exhibit larger insertion widths of the medial recti. Medial/lateral ratio of LI distances were significantly lower and insertion widths were significantly higher in the SAACE compared to the control group (P< 0.05).Conclusion: Based on the observations of more anterior insertion and larger muscle widths, this suggests there are stronger forces of medial recti in SAACE. In addition to excessive accommodation followed by increases in medial recti tonus, the results also suggest that an anatomical imbalance between lateral and medial recti contributes to esotropia onset following excessive near work.Keywords: acute acquired concomitant esotropia, digital devices, extraocular muscles, insertion distance, insertion width

The extraocular muscles (EOMs) are implicated in a variety of local and systemic diseases. Often, the pattern of disease on imaging, along with the clinical presentation, can lead the ophthalmologist and radiologist toward a specific diagnosis. This article provides a comprehensive pictorial review of common pathologies affecting EOM, with an emphasis on the unique imaging characteristics that help in clinching the diagnosis.

Introduction: Paralytic strabismus, a type of strabismus caused by paralysis of one or more extraocular muscles, can lead to a variety of ocular and psychosocial sequelae. Etiology varies in different types of paralytic strabismus. Numerous studies have shown that ocular motor cranial nerve palsies have a variety of causes including vascular disease, head trauma, intracranial tumour or aneurysm and inflammatory disorders.Materials and Methods: A cross-sectional study was conducted at a tertiary eye hospital to evaluate Paralytic squint by Neuroimaging in patients presenting to the Squint department of Sarojini Devi Eye Hospital Hyderabad from June 2021 to May 2022. Paralytic strabismus cases with limitation of ocular motility were enrolled and a detailed examination was performed to know the etiology. Results: 190 patients (1.35%) were diagnosed with paralytic strabismus. Ischemia constituted to be the major cause of paralytic strabismus i.e. (42.1%) followed by trauma (20%). The 3rd cranial nerve was the most commonly involved (34.73%), followed by the 6th cranial nerve (32.63%). Multiple cranial nerves were involved in 20% of cases. The 3rd CN was involved, primarily due to ischemia in both males and females while the 6th CN was affected with trauma, neoplasm, and ischemia being prominent causes. Conclusion: The study showed that ischemia, trauma and idiopathy are some of the major etiologies of paralytic strabismus with male predominance. The cranial nerve involvement also varied with the etiology of paralytic strabismus.

Skeletal muscle stem cells (MuSCs) are recognised as functionally heterogeneous. Cranial MuSCs are reported to have greater proliferative and regenerative capacity when compared with those in the limb. A comprehensive understanding of the mechanisms underlying this functional heterogeneity is lacking. Here, we have used clonal analysis, live imaging and single cell transcriptomic analysis to identify crucial features that distinguish extraocular muscle (EOM) from limb muscle stem cell populations. A MyogeninntdTom reporter showed that the increased proliferation capacity of EOM MuSCs correlates with deferred differentiation and lower expression of the myogenic commitment gene Myod. Unexpectedly, EOM MuSCs activated in vitro expressed a large array of extracellular matrix components typical of mesenchymal non-muscle cells. Computational analysis underscored a distinct co-regulatory module, which is absent in limb MuSCs, as driver of these features. The EOM transcription factor network, with Foxc1 as key player, appears to be hardwired to EOM identity as it persists during growth, disease and in vitro after several passages. Our findings shed light on how high-performing MuSCs regulate myogenic commitment by remodelling their local environment and adopting properties not generally associated with myogenic cells. [ABSTRACT FROM AUTHOR]

MYH13 is a unique type of sarcomeric myosin heavy chain (MYH) first detected in mammalian extraocular (EO) muscles and later also in vocal muscles, including laryngeal muscles of some mammals and syringeal muscles of songbirds. All these muscles are specialized in generating very fast contractions while producing relatively low force, a design appropriate for muscles acting against a much lower load than most skeletal muscles inserting into the skeleton. The definition of the physiological properties of muscle fibres containing MYH13 has been complicated by the mixed fibre type composition of EO muscles and the coexistence of different MYH types within the same fibre. A major advance in this area came from studies on isolated recombinant myosin motors and the demonstration that the affinity of actin‐bound human MYH13 for ADP is much weaker than those of fast‐type MYH1 (type 2X) and MYH2 (type 2A). This property is consistent with a very fast detachment of myosin from actin, a major determinant of shortening velocity. The MYH13 gene arose early during vertebrate evolution but was characterized only in mammals and birds and appears to have been lost in some teleost fish. The MYH13 gene is located at the 3′ end of the mammalian fast/developmental gene cluster and in a similar position to the orthologous cluster in syntenic regions of the songbird genome. MYH13 gene regulation is controlled by a super‐enhancer in the mammalian locus and deletion of the neighbouring fast MYH1 and MYH4 genes leads to abnormal MYH13 expression in mouse leg muscles. [ABSTRACT FROM AUTHOR]

The article presents a three-dimensional linear model of the vestibulo-ocular reflex in darkness. The model is based on established relationships between the vestibular system and the extraocular muscles. The effectiveness of the model is evaluated through comparison with experimental observations. The model successfully reproduces realistic patterns of slow-phase vestibulo-ocular nystagmus during head rotations. [ABSTRACT FROM AUTHOR]

Background. According to the literature, an increase in the volume of soft tissues behind the eyeball due to an increase in the volume of the extraocular muscles (EOM) and/or orbital adipose tissue is the cause of exophthalmos, limited eye movement, diplopia, and in some cases can lead to optic neuropathy, which is a severe complication of endocrine orbitopathy. Thus, the optimization of the diagnosis of endocrine orbitopathy, in particular in the aspect of evaluating its various forms and choosing the method of orbital decompression as the main method of treatment, is an urgent interdisciplinary problem. The purpose of the work is to conduct a comparative analysis of the total volume of soft tissue contents of the orbit and individual volumes of extraocular muscles, orbital adipose tissue, and optic nerve by computer modeling in patients with endocrine orbitopathy and without orbital pathology. Materials and methods. Іn this retrospective cohort study, computed tomography data of 114 patients with and without endocrine orbitopathy, who were divided into 2 groups, were analyzed. Orbital soft tissue volumes were calculated in Mimics Medical 23.0 software (Materialise, Belgium). The obtained data were evaluated by methods of variable statistics using the Shapiro-Wilk test and the Mann-Whitney test for independent samples. Results. The average volume of the orbit in the main group was 26,196.39 ± 3,117.50 mm3, in the control group — 26,980.49 ± 3,765.82 mm3 and did not differ significantly (р = 0.405). The average volume of extraocular muscles in the main group is 7,650.77 ± 3,047.96 mm3, and in the control group — 2,871.73 ± 644.99 mm3 (р = 0.0001). The average volume of the orbital adipose tissue in the main group was equal to 17,956.38 ± 3,273.53 mm3, and in the control group — 23,695.76 ± 3,791.63 (р = 0.0001). Conclusions. The study showed the absence of correlation in the volume of the orbit, and its presence between the volume of extraocular muscles and orbital adipose tissue in patients with endocrine orbitopathy and in the control group. The ratio of the average volume of adipose tissue to the average volume of the EOM in the main group was 2.79 : 1, and in the control group, 8.73 : 1. This indicator is an important argument when deciding on the method of orbital decompression — with a predominant increase in the average volume of the EOM, bony orbital decompression is indicated, with a predominant increase in the average volume of adipose tissue — fat orbital decompression, and with a uniform increase in the average volume of the EOM and the average volume of adipose tissue, combined orbital decompression will be optimal. The use of this approach can become a promising method in the differential diagnosis of endocrine orbitopathy, in particular in the aspect of evaluating its various forms and when planning orbital decompression as the main method of its treatment. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to investigate the morphometric development of the extraocular muscles in the fetal period and to create a modified Tillaux spiral. Methods: We dissected 157 fetal eyes (82 right eyes, 75 left eyes) obtained from 79 fetuses (46 boys, 33 girls) between 13 and 40 weeks of gestation. The tendon widths of the extraocular muscles and the distances of the tendon attachment sites to the limbus were measured. Tillaux's modified spiral was created. Results: In addition to the rectus muscles, we added tendon widths and tendon–limbus distances of the upper (SO) and lower (IO) obliques to the modified Tillaux spiral. When tendon widths were compared between genders, no statistically significant difference was observed. When tendon widths were compared between the sides, it was determined that SO was more in the left eye, whereas other extraocular muscles were more in the right eye. There was no statistically significant difference between genders when the distances of tendon attachment sites to the limbus were compared. There was no statistically significant difference in SO and IO values between the sides. There was a statistically significant difference in the rectus muscles and this difference was found to be higher in the right eye. Conclusion: We think that the findings obtained will contribute to disciplines such as fetopathology, obstetrics, ophthalmology and plastic surgery and to future studies on this subject. [ABSTRACT FROM AUTHOR]

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Strabismus is a genetically heterogeneous disorder with complex molecular and neurophysiological causes. Evidence in the literature suggests a strong role for motor innervation in the etiology of strabismus, which connects central neural processes to the peripheral extraocular muscles. Current treatments of strabismus through surgery show that an inherent sensorimotor plasticity in the ocular motor system decreases the effectiveness of treatment, often driving eye alignment back toward its misaligned pre-surgical state by altering extraocular muscle tonus. There is recent interest in capitalizing on existing biological processes in extraocular muscles to overcome these compensatory mechanisms. Neurotrophins are trophic factors that regulate survival and development in neurons and muscle, including extraocular muscles. Local administration of neurotrophins to extraocular muscles partially reversed strabismus in an animal model of strabismus. The hypothesis is that sustained release of neurotrophins gives more time for the ocular motor system to adapt to a slow change in alignment in the desired direction. The effect of neurotrophins on extraocular muscles is complex, as different neurotrophic factors have diverse effects on extraocular muscle contraction profiles, patterns of innervation, and density of extraocular muscle precursor cells. Neurotrophic factors show promise as a therapeutic option for strabismus, which may help to improve treatment outcomes and offset devastating amblyopia and psychosocial effects of disease in strabismus patients.

Vision relies on precise eye movements controlled by six extraocular muscles (EOMs). Training kits and functional eye models are crucial for ophthalmological studies. The study investigates the potential of shape memory material (SMM) in ophthalmology, focusing on eye model mechanics and four thermally actuated smart EOMs. SMM was chosen over other actuators because of its high-power density (36 W/kg), high actuation forces (100 gf), and high displacements (200%). Finite element method (FEM) simulation on a 3D eye model was performed to analyze the thermo-mechanical properties of smart muscle, revealing the shape memory effect and super elasticity which result in the four eye movements of elevation, depression, adduction, and abduction. FEM simulation, compared to the eye model prototype, yielded a 16 mm deformation in smart muscle with a thermal actuation of 313 K (40 °C). FEM analysis, while combining smart muscle with the eye model, resulted in a 6.8517 mm deformation in the simulation. Prototype deformation was acquired as 7.262 mm. The successful actuation of the eye using thermally actuated smart muscles proves its potential for ophthalmology kits. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the relationship between clinical features and protein amounts of Cysteine-rich 61 (Cyr61/CCN1) and connective tissue growth factor (CTGF/CCN2), which are vital components and regulators of the extracellular matrix in resected muscles from strabismus surgery. Methods: Strabismus patients who were diagnosed with horizontal concomitant strabismus or inferior oblique overaction (IOOA) and required extraocular muscles (EOMs) resection to correct eye position were included in this study. The protein amounts were measured by enzyme-linked immunosorbent assay (ELISA) in resected EOMs. Multivariable linear regression was used to investigate the associations, adjusting for gender, age (continuous), amblyopia, and disease duration. Results: A total of 141 muscles (including 38 lateral, 81 medial rectus, and 22 inferior oblique muscles) from 128 patients were collected in this study. The amount of Cry61 and CTGF per millimeter was significantly negatively associated with deviation angle in intermittent exotropia patients (Cry61: β, − 1.44; 95%CI, − 2.79 to − 0.10, p = 0.035; CTGF: β, − 3.14; 95%CI, − 5.06 to − 1.22, p = 0.002). The same relationship was also detected in the partially accommodative and non-accommodative esotropia patients, although it was not statistically significant (Cry61: β, − 2.40; 95%CI, − 5.05 to 0.24; p = 0.073; CTGF: β, − 3.47; 95%CI, − 9.18 to 2.87; p = 0.269). The amount of Cry61 and CTGF per millimeter showed significant associations with the degree of IOOA (p < 0.05). Conclusions: Taken together, our results demonstrated a significant relationship between deviation angle and protein amount of Cry61 and CTGF and implied that Cry61 and CTGF may play important roles in modulation of EOM contractility, which provide new insights into strabismus pathogenesis. [ABSTRACT FROM AUTHOR]

One of the most common untoward occurrences during strabismus surgery at all ages is the oculocardiac reflex. Although typically easily treated, the sudden bradycardia or cardiac arrest may add a few gray hairs to ophthalmologists and anesthesiologists alike as it can be potentially fatal. This updated review of the literature and novel detailed treatment algorithm may prevent patient morbidity and mortality through proper recognition of at-risk patients and rapid treatment through proper communication between surgical and anesthesia physicians/providers. • Lessening muscular tension may be accomplished while leaving instruments on the field and moving the eye into primary position. • If suture adjustment is anticipated, special attention should be paid to those with a positive intraoperative OCR. • Volatile anesthetics are associated with a lower incidence of the OCR and may be preferred during ocular surgery. • Total intravenous anesthetic techniques with propofol or remifentanil should be avoided to reduce incidence and severity of OCR. • Peribulbar blockade appears most effective for reduction of OCR incidence compared with other ocular nerve blocks. [ABSTRACT FROM AUTHOR]

Strabismus is not a condition in itself but the consequence of an underlying problem. Eye misalignment can be caused by disease, injury, and/or abnormalities in any of the structures and processes involved in visual perception and oculomotor control, from the extraocular muscles and their innervations to the oculomotor and visual processing areas in the brain. A small percentage of all strabismus cases are the consequence of well-described genetic syndromes, acquired insult, or disease affecting the extraocular muscles (EOMs) or their innervations. We will refer to them as strabismus of peripheral origin since their etiology lies in the peripheral nervous system. However, in most strabismus cases, that is comitant, non-restrictive, non-paralytic strabismus, the EOMs and their innervations function properly. These cases are not related to specific syndromes and their precise causes remain poorly understood. They are generally believed to be caused by deficits in the central neural pathways involved in visual perception and oculomotor control. Therefore, we will refer to them as central strabismus. The goal of this narrative review is to discuss the possible causes behind this particular type of eye misalignment and to raise awareness among eyecare professionals about the important role the central nervous system plays in strabismus etiology, and the subsequent implications regarding its treatment. A non-systematic search was conducted using PubMed, Medline, Cochrane, and Google Scholar databases with the keywords "origins," "causes," and "etiology" combined with "strabismus." A snowball approach was also used to find relevant references. In the following article, we will first describe EOM integrity in central strabismus; next, we will address numerous reasons that support the idea of central nervous system (CNS) involvement in the origin of the deviation, followed by listing several possible central causes of the ocular misalignment. Finally, we will discuss the implications CNS etiology has on strabismus treatment. [ABSTRACT FROM AUTHOR]

(1) Background: Myopia is one of the most common refractive errors in the world. The aim of this study was to evaluate the transverse dimensions of selected masticatory muscles (temporalis muscle and masseter muscle) versus the transverse dimensions of selected extraocular muscles (superior rectus, inferior rectus, medial rectus and lateral rectus) in emmetropic and high myopic subjects. (2) Methods: Twenty-seven individuals were included in the analysis, resulting in 24 eyeballs of patients with high myopia and 30 eyeballs of emmetropic subjects. A 7 Tesla resonance was used to analyze the described muscles. (3) Results: Statistical analysis showed differences in all analyzed extraocular muscles and all analyzed masticatory muscles between emmetropic subjects and high myopic subjects. In the high myopic subject group, statistical analysis showed four correlations. The three negative correlations were between the lateral rectus muscle and an axial length eyeball, refractive error and an axial length eyeball, and the inferior rectus muscle and visual acuity. The positive correlation was between the lateral rectus muscle and the medial rectus muscle. (4) Conclusions: The high myopic subjects are characterized by a larger cross-sectional area of extraocular muscles and masticatory muscles compared to the emmetropic subjects. Correlations were observed between the thickness of the extraocular muscles and the masticatory muscles. The lateral rectus muscle was related to the length of the eyeball. The phenomenon requires further study. [ABSTRACT FROM AUTHOR]

Purpose: To study the role of muscle biopsy in patients with enlarged extraocular muscles. Methods: A retrospective review of 31 patients who underwent biopsy for extraocular muscle enlargement. Characteristics, including signs, symptoms, imaging findings, and histopathological assessment were examined. Results: Chronic inflammatory disorders represented the most common cause of the muscle enlargement followed by malignancy/metastasis. Multiple muscle involvement was more consistent with benign diseases, whereas single muscle involvement was more consistent with malignant causes. Positive predictive value of muscle biopsy was 0.52 for determining a specific cause of the muscle enlargement. Conclusions: Muscle biopsy is the standard for diagnosis in patients with extraocular muscle enlargement. This diagnostic test should be performed in every case of non-resolving muscle enlargement, with a specific diagnosis being made in over half of cases. [ABSTRACT FROM AUTHOR]

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. 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. 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). This normative data may be used to diagnose pathological enlargement of the optic nerve and extraocular muscles, including involvement of the oblique muscles. [ABSTRACT FROM AUTHOR]

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

OBJECTIVE: The study aims to determine the parameters affecting Apparent diffusion coefficient (ADC) values of extraocular muscles (EOM). METHODS: This retrospective descriptive study was conducted with clinically normal 300 patients (150 females, 150 males; mean age, 42,93 - 19,19 - range 18-96 years-old). MRI had performed by applying 0-1000 s/mm2 b value and EPI technique. ADC values were evaluated from medial and lateral rectus muscles and classified according to four main parameters [Age, side (right/Left), gender and muscle type]. RESULTS: Age: ADC values of EOM statistically increased with age (p:<0,05) at the rate of reaching a maximum of 0.413 10-3 mm2/s. The difference in ADC values was approximately 40% from 18 years old to the maximum age. Side, gender, muscle type: Graphically and numerically, ADC values of males were higher than females in the right eye. This situation was statistically more significant in the 18-30 age group (p: 0,047 for right medial rectus, p: 0,01 for right lateral rectus). There was no significant difference between the right and left eyes in the total population. Although the presence a divergence in the ADC values between females and males in the right eye, the dominant and recessive eye s values were similar (p> 0,05). CONCLUSION: It is not possible to make mention an absolute normal ADC value for EOM. The ADC values vary according to age and gender. Age is the main parameter which affects ADC values. Gender is effective on values in the early age group and right eye (mainly dominant eye in the total population). The side of EOM and muscle type are not parameters that significantly affect the ADC values. [ABSTRACT FROM AUTHOR]

Purpose: To investigate feasibility and diagnostic performance of turbo gradient and spin-echo BLADE (proprietary name for Periodically Rotated Overlapping ParallEL Lines with Enhanced Reconstruction [PROPELLER] in Siemens MR systems)-diffusion weighted imaging (TGSE-BLADE-DWI) for depicting extraocular muscle (EOM) involvement and activity in thyroid-associated ophthalmopathy (TAO), and to compare TGSE-BLADE-DWI with readout-segmented echo-planar imaging (RESOLVE). Materials and methods: Thirty-five patients with identified TAO underwent the two DWI scans. Two radiologists visually scored the image quality of the two DWIs with respect to the susceptibility artifacts and geometric distortions on a three-point scale. The maximum size (Sizemax) of EOMs and corresponding ADCs (cADCs) of each patient were compared between the active and inactive phases. The clinical activity score (CAS) was used as a reference to assess the diagnostic performance of EOM ADCs for grading TAO activity. ROC analysis, Pearson correlation, and Wilcoxon signed-rank test were used for statistical analyses. Results: For scores of EOMs, the image quality of TGSE-BLADE-DWI was significantly higher than that of RESOLVE. There were no statistically significant differences between the AUCs of the two DWIs, Sizemax, or cADCs between the active and inactive phases. TGSE-BLADE-DWI ADCs were significantly higher than the RESOLVE ADCs in the right superior rectus, right lateral rectus, left superior rectus, and left inferior rectus. There were no statistically significant correlations between the cADC or Sizemax, and CAS. The highest AUC was 0.697 for RESOLVE and 0.657 for TGSE-BLADE-DWI. The best performing ADC threshold was 1.85 × 10−3 mm2/s with 85.7% sensitivity, 58.8% specificity and 66.67% accuracy for RESOLVE and 1.99 × 10−3 mm2/s with 79.0% sensitivity, and 55.6% specificity and 65.27% accuracy for TGSE-BLADE-DWI. Conclusion: Compared to RESOLVE, TGSE-BLADE-DWI provided improved image quality with fewer susceptibility artifacts and geometric distortions for EOM visualization and showed an equivalent performance in detecting active TAO. [ABSTRACT FROM AUTHOR]

The purpose was to ascertain if any relation exists between the elevated intraocular pressure (IOP) in patients with thyroid-associated orbitopathy (TAO) in active stage and the severity of extraocular muscle involvement and the extent of exophthalmos. Methods: A total of 96 eyes and orbits of 48 adult patients with active TAO were investigated. All patients underwent magnetic resonance imaging of the orbit and measurement of all extraocular recti muscles (EOM). The obtained data was divided into two groups according to the IOP value: normal IOP ≤ 21 mmHg; n = 47 and elevated IOP with IOP > 21 mmHg; n = 49, and analyszed. Results: A significant difference was found in the short diameter of medial rectus and inferior rectus muscles and in the sum of short parameters of all EOM. All these parameters were significantly higher in the elevated IOP group. Motility restriction in at least one gaze direction was also significantly more frequent (p < 0.0001) in the elevated IOP group. A positive moderate correlation was found between IOP and the sum of short parameters of EOM (r = 0.496). No correlation was found between the IOP and exophthalmos values (r = 0.267). During the follow-up, the frequency of strabismus surgery and orbital decompression was significantly higher in the elevated IOP group (p = 0.003; p = 0.002). Conclusion: Elevated IOP in the active TAO stage particularly correlates with extraocular muscle involvement. These patients are also more likely to require orbital decompression and strabismus surgery. [ABSTRACT FROM AUTHOR]

Abstract Background Studies on the factors related to lacrimal gland prolapse (LGP) in patients with thyroid-associated ophthalmopathy (TAO) are limited. This study aimed to assess the factors associated with LGP on magnetic resonance imaging (MRI) and its relation to TAO activity . Methods Thirty-six patients (72 orbits) with inactive TAO (43 orbits, Clinical Activity Score [CAS]

Cluster headaches are a series of short, excruciating, and unilateral pain that happens for a short period at a time over days, weeks, or months and may awake people from sleep. It is situated behind, in, or around one eye only with possible radiation to the forehead at the same side. Cluster headache is characterized by many ocular features. However, extraocular muscle involvement is unusual in this type of headache. We present a case of chronic cluster headache associated with diplopia due to oculomotor nerve palsy in a 24-year-old man, which responded successfully to oral steroid. This presentation is rare. Therefore, ophthalmologists and neurologists should consider it in their list of a differential diagnosis. A short course of oral prednisolone has a role in the management of patients in such cases.

Vertebrate locomotion presents a major challenge for maintaining visual acuity due to head movements resulting from the intimate biomechanical coupling with the propulsive musculoskeletal system. Retinal image stabilization has been traditionally ascribed to the transformation of motion-related sensory feedback into counteracting ocular motor commands. However, extensive exploration of spontaneously active semi-intact and isolated brain/spinal cord preparations of the amphibian Xenopus laevis, have revealed that efference copies (ECs) of the spinal motor program that generates axial- or limb-based propulsion directly drive compensatory eye movements. During fictive locomotion in larvae, ascending ECs from rostral spinal central pattern generating (CPG) circuitry are relayed through a defined ascending pathway to the mid- and hindbrain ocular motor nuclei to produce conjugate eye rotations during tail-based undulatory swimming in the intact animal. In post-metamorphic adult frogs, this spinal rhythmic command switches to a bilaterally-synchronous burst pattern that is appropriate for generating convergent eye movements required for maintaining image stability during limb kick-based rectilinear forward propulsion. The transition between these two fundamentally different coupling patterns is underpinned by the emergence of altered trajectories in spino-ocular motor coupling pathways that occur gradually during metamorphosis, providing a goal-specific, morpho-functional plasticity that ensures retinal image stability irrespective of locomotor mode. Although the functional impact of predictive ECs produced by the locomotory CPG matches the spatio-temporal specificity of reactive sensory-motor responses, rather than contributing additively to image stabilization, horizontal vestibulo-ocular reflexes (VORs) are selectively suppressed during intense locomotor CPG activity. This is achieved at least in part by an EC-mediated attenuation of mechano-electrical encoding at the vestibular sensory periphery. Thus, locomotor ECs and their potential suppressive impact on vestibular sensory-motor processing, both of which have now been reported in other vertebrates including humans, appear to play an important role in the maintenance of stable vision during active body displacements.

Vision relies on precise eye movements controlled by six extraocular muscles (EOMs). Training kits and functional eye models are crucial for ophthalmological studies. The study investigates the potential of shape memory material (SMM) in ophthalmology, focusing on eye model mechanics and four thermally actuated smart EOMs. SMM was chosen over other actuators because of its high-power density (36 W/kg), high actuation forces (100 gf), and high displacements (200%). Finite element method (FEM) simulation on a 3D eye model was performed to analyze the thermo-mechanical properties of smart muscle, revealing the shape memory effect and super elasticity which result in the four eye movements of elevation, depression, adduction, and abduction. FEM simulation, compared to the eye model prototype, yielded a 16 mm deformation in smart muscle with a thermal actuation of 313 K (40 °C). FEM analysis, while combining smart muscle with the eye model, resulted in a 6.8517 mm deformation in the simulation. Prototype deformation was acquired as 7.262 mm. The successful actuation of the eye using thermally actuated smart muscles proves its potential for ophthalmology kits.