Medial Rectus Research Articles

Medial Rectus Advancement Compared to Lateral Rectus Recession for Small To Moderate Angle Consecutive Exotropia

Medial Rectus Advancement Compared to Lateral Rectus Recession for Small To Moderate Angle Consecutive Exotropia

Relative contribution of lateral vestibular neuron and abducens internuclear neuron inputs to the discharge activity of medial rectus motoneurons

Medial rectus motoneurons mediate nasally directed horizontal eye movements. These motoneurons receive two major excitatory inputs, from the abducens internuclear neurons (ABD Ints) and neurons of the lateral vestibular nucleus whose axons course through the ascending tract of Deiters (ATD). In the present work, we have recorded in the alert chronic cat preparation the discharge activity of these two premotor neurons simultaneously with eye movements, to discern their relative contribution to the firing pattern of medial rectus motoneurons. ABD Int discharge was accurately correlated with eye movements, displaying high sensitivities to eye position and eye velocity. ATD neurons also discharged in relation to spontaneous and vestibular eye movements but showed significantly lower eye position and eye velocity sensitivities. Outstandingly, ATD neurons presented a significantly lower eye position threshold for recruitment compared to both ABD Ints and medial rectus motoneurons. Therefore, ATD neurons exhibited eye position and velocity signals during spontaneous and vestibular eye movements, which were of lower magnitude than those of ABD Ints, but due to their low recruitment threshold, they could play a significant role in facilitating ABD Int signal transmission onto medial rectus motoneurons.

The Immunoarchitecture of Human Extraocular Muscles.

The purpose of this study was to describe the immunoarchitecture of normal extraocular muscles (EOMs) in terms of presence, distribution, and organization of various immune cells. We performed unilateral orbital exenterations in six fresh human cadavers from elderly patients, followed by dissection of the medial, lateral, superior and inferior rectus, superior and inferior oblique, and superior palpebral levator muscle in their entirety. We further cross sectioned each EOM in an anterior, central, and posterior third. After immunohistochemical staining for CD3, CD8, CD20, CD138, CD68, and podoplanin, quantitative analysis was performed. We found all EOMs (rectus, oblique, and levator muscles) to harbor both T- and B-lymphocytes, with a B-lymphocyte dominance and an absence of plasma cells. The highest prevalence of immune cells was seen in the muscle bellies, with, on average, 488 ± 63 CD3+ T-lymphocytes and 44 ± 110 CD20+ B-lymphocytes per mm2, and significant differences from the anterior (T-lymphocytes) and posterior (T- and B-lymphocytes) thirds. T- and B-lymphocytes were primarily organized in hotspots in the vicinity of blood vessels. In addition, a small resident population of macrophages scattered throughout the specimens was detected. No lymphatic vessels were found in any of the EOMs. These findings can serve as a reference dataset in the assessment of EOM biopsies in the diagnostic process of inflammatory orbital and systemic disorders. Moreover, from a regenerative perspective, our results highlight the importance of taking into account the presence of a resident immune cell population when studying the host immune response on transplanted tissues or engineered constructs.

Clinical Characteristics and Outcomes after Augmented Medial Rectus Muscle Recession in Patients with Acute Acquired Comitant Esotropia

Purpose: To analyze the clinical characteristics of patients with acute acquired comitant esotropia, evaluate the outcomes of augmented medial rectus muscle recession, and propose indicators for determining the appropriate surgical dosage.Methods: Data of patients with acute acquired esotropia who underwent medial rectus recession between 2016 and 2022 were retrospectively analyzed. The amount of medial rectus muscle recession was 1-2 mm greater than for other types of esotropia. Surgical success was assessed by reference to the angle of deviation and diplopia status 6 months after surgery. We investigated the amount of additional recession required for favorable surgical outcomes, the characteristics of groups that required augmentation, and changes in surgical amount according to the deviation angle.Results: A total of 38 patients were included; the average refractive error was -3.79 ± 3.11 diopters (D). Patient age at the time of surgery was 25.6 ± 18.2 years and the preoperative deviation angle was 38.1 ± 11.5 prism diopters (PD). The amount of medial rectus muscle recession was 6.25 ± 1.4 mm, i.e., 1.2 ± 1.0 mm greater than during other surgeries. The average augmentation was 24.1 ± 18.8%. The motor surgical success rate was 92.1% and the sensory success rate was 97.4%. The required augmentation was 26.9% for those with angles of deviation < 30 PD, 25.5% for patients with angles between 30 and 40 PD, and 20.0% for those with angles > 40 PD. Patients who required augmentation > 25% were older, and the surgical effect was greater as the angle of deviation increased.Conclusions: To ensure successful surgical outcomes of patients with acute acquired comitant esotropia, it is essential to increase the amount of medial rectus recession compared to that during other surgeries; the average augmentation was 24% in this study.

Structural and functional multilayer network analysis in restless legs syndrome patients.

The combination of brain structural and functional connectivity offers complementary insights into its organisation. Multilayer network analysis explores various relationships across different layers within a single system. We aimed to investigate changes in the structural and functional multilayer network in 69 patients with primary restless legs syndrome (RLS) compared with 50 healthy controls. Participants underwent diffusion tensor imaging (DTI) and resting state-functional magnetic resonance imaging (rs-fMRI) using a three-tesla MRI scanner. We constructed a structural connectivity matrix derived from DTI using a DSI program and made a functional connectivity matrix based on rs-fMRI using an SPM program and CONN toolbox. A multilayer network analysis, using BRAPH program, was then conducted to assess the connectivity patterns in both groups. At the global level, significant differences there were between the patients with RLS and healthy controls. The average multiplex participation was lower in patients with RLS than in healthy controls (0.804 vs. 0.821, p = 0.042). Additionally, several regions showed significant differences in the nodal level in multiplex participation between patients with RLS and healthy controls, particularly the frontal and temporal lobes. The regions affected included the inferior frontal gyrus, medial orbital gyrus, precentral gyrus, rectus gyrus, insula, superior and inferior temporal gyrus, medial and lateral occipitotemporal gyrus, and temporal pole. These results represent evidence of diversity in interactions between structural and functional connectivity in patients with RLS, providing a more comprehensive understanding of the brain network in RLS. This may contribute to a precise diagnosis of RLS, and aid the development of a biomarker to track treatment effectiveness.

Decrease of over-elevation in adduction after surgery of medial rectus muscles in partially refractive accommodative esotropia.

The course of over-elevation in adduction after strabismus surgery has been evaluated in a small number of research in the literature, we believe our study is the first to report the results in a specific group of esotropia (ET) patients. To report the course of postoperative over-elevation in adduction in patients who underwent surgery for horizontal deviation on the medial recti in partially accommodative ET. The medical charts of patients who had partially accommodative ET with over-elevation in adduction were reviewed retrospectively. A scale from -4 to +4 was used to grade the oblique muscle function. Among these, 17 patients who were operated solely on the horizontal rectus muscles were identified. The primary outcome measure was the degree of improvement in over-elevation in adduction after medial rectus surgery. Nine (52.9%) of the 17 patients (mean age: 5.18 ± 2.24 months) were males and 8 (47.1%) were females. The mean follow-up period was 17.06 ± 15.32 months. Overall, 15 patients (88.2%) achieved surgical success. The mean inferior oblique overaction was found 1.44 ± 0.56 preoperatively and the final postoperative mean inferior oblique overaction was 0.53 ± 0.51 (P = 0.001). Postoperative over-elevation in adduction after 3 months was significantly decreased compared to the preoperative value (P = 0.003, P = 0.001, P = 0.001 at 3rd and 6th months and final visits respectively). Over-elevation in adduction accompanying partially refractive accommodative ET seems to regress after medial rectus weakening surgery. This finding should be considered in the presurgical evaluation of these patients.

Clinical Insights into Internuclear Ophthalmoplegia: A Case Report

Background: Internuclear ophthalmoplegia (INO) is a rare neuro-ophthalmological disorder characterized by impaired horizontal eye movement coordination due to lesion in the medial longitudinal fasciculus. INO commonly results from demyelinating diseases, vascular lesions, or structural brain abnormalities.
 Case presentation: A 60-year-old male patient presented with diplopia for the past 4 days. He had history of hypertension and diabetes mellitus and “mild” stroke for past years. Clinical examination revealed normal primary gaze, limited medial movement of the left eye, and diplopia in all gaze positions. Hess screen examination demonstrated underaction of the left medial rectus muscle and overaction of the right lateral rectus muscle. The laboratory results an elevated blood sugar level. Brain CT scan revealed multiple infarcts in the right parietal and cerebellar lobes and left parieto-occipital lobe, with evidence of brain atrophy. The patient was diagnosed with INO. Management involved addressing the underlying systemic diseases, namely diabetes and hypertension, in collaboration with internist and neurologist. The patient also received citicoline therapy and underwent regular follow-up. In the third-month follow-up, the patient demonstrated significant improvement, with reduction in diplopia and enhancement in left eye medial movement.
 Conclusion: This case report highlights the importance of considering INO in patients presenting with diplopia and a history of vascular risk factors. Timely diagnosis and comprehensive management with regular follow-up is crucial to monitor the progress and enhance the patient's quality of life.

Preoperative visual function characteristics having an effect on the success of exotropia surgery

Background: There are individual reports on the effect of some preoperative characteristics of visual functions (like convergence, angle of deviation, presence of fusion and type of binocular vision) on the success of exotropia surgery. To date, however, it has not been established what are the major diagnosis-related prognostic factors for the success of surgery for exotropia. Purpose: To identify the preoperative characteristics of visual functions which have an effect on the success of surgery for exotropia. Material and Methods: Of the 59 exotropes (age range, 10 to 21 years) included in this study, 33 had basic constant exotropia (group 1) and 26, intermittent exotropia (group 2). Patients underwent an ophthalmological and ortoptic examination of the motor and sensory systems of the eye. Patients with surgery success (postoperative orthotropes) were compared to those who had a residual exotropia of more than 10 prism diopters (PD) postoperatively in terms of the preoperative accommodative convergence–accommodation (AC/A) ratio, near point of convergence (NPC), distance stereopsis and near stereoacuity threshold. Results: Our analysis of the preoperative NPC, AC/A ratio and stereopsis for the group with postoperative orthotropic alignment and the group with postoperative exotropic alignment found preoperative close to normal values of AC/A ratio (4.0 ± 1.65 PD/D), NPC (8.03 ± 3.02 cm), the presence of distance stereopsis and near stereopsis (passing the 200 second of arc image on the Lang II stereo card) and the absence of medial rectus hypofunction of hyperfunction in 83.05% of patients of the former group. Conclusion: Preoperative close to normal values of AC/A ratio (4.0 ± 1.65 PD/D), NPC (8.03 ± 3.02 cm), the presence of distance stereopsis and near stereopsis (passing the 200 second of arc image on the Lang II stereo card) and the absence of medial rectus hypofunction of hyperfunction can be the factors favoring the success of exotropia surgery.

A rare case report: isolated midbrain lacunar infarct affecting the ipsilateral medial longitudinal fasciculus causing internuclear ophthalmoplegia effect

Isolated medial longitudinal fasciculus infarct is rare and can also be associated with cranial nerve nuclei or extra-nuclear regions leading to respective neurological deficit. We report a case of 73-year-old woman presenting with a 24 hour of confusion, abnormal eye movement and unsteady gait on a background history of uncontrolled diabetes mellitus (DM), hypertension and Alzheimer’s disease. Her examination found to have dysdiadokinesia in left upper limb and inability to adduct right eyeball on left lateral gaze, without affecting the pupil. She was not oriented to time and place while before this event she could. Her examination found to have normal power in limbs and sensation. Her computed tomography (CT) brain showed no evidence of acute infarction or intracranial bleed. Magnetic resonance imaging (MRI) brain demonstrated acute lacunar infarct involving the ipsilateral medial longitudinal fasciculus. This case demonstrates rare brainstem infarct affecting medial longitudinal fasciculus region below the IIIrd cranial nerve nucleus giving features of internuclear ophthalmoplegia affecting medial rectus muscle without affecting autonomic fibres of IIIrd cranial nerve due to which the pupil is not affected. We recommend strict control of predisposing conditions, mainly diabetes and hypertension to reduce the incidence of brainstem stroke.

Misplaced Intracystic Lacrimal Implant- An Unusual Cause of Failed External Dacryocystorhinostomy.

Various techniques of dacryocystorhinostomy (DCR) by an external or endonasal endoscopic approaches are in practice of ophthalmologists and otorhinolaryngologists. The purpose of this paper is to report a case of misplaced intracystic implant in the orbit following external DCR leading to persistence of watering, diplopia and visual diminution. A thirty nine year old female patient presented with recurrent left eye pain, swelling over medial side of the left eye, watering, progressive blurring of vision and diplopia after revision external DCR. The ophthalmology examination revealed bilateral decreased vision, left side restricted extraocular eye movements, sub capsular cataract. The computed tomography dacryocystograph (CT-DCG) revealed tubular foreign body in the extra-conal space abutting the medial rectus with proximal block in the nasolacrimal duct. This is the first reported case of misplaced implant following external DCR in the literature. It may be suggested that patients undergoing intracystic larimal implant shall be on close follow up for such an occurrence later for timely intervention.

Novel Instrument for Clinical Evaluations of Active Extraocular Muscle Tension

Strabismus can be caused by abnormal tension of the extraocular muscles (EOMs) attached to the eyeball in superior, inferior, lateral, medial, superior oblique, and inferior oblique positions. Evaluating the tension in each EOM is crucial for surgical planning in strabismus, which is conducted by adjusting the tension on the EOM. The purpose of this study was to develop a compact measuring device to non-invasively evaluate the active EOM tension. The proposed device employed a cotton-tipped medical swab to transfer the EOM tension connected to the force sensor as a non-invasive medium. The tilting angle of the swab and the force of active EOM tension were wirelessly transferred to a laptop computer for recording and real-time displaying of the measured values. The active EOM tensions for the four recti muscles were 101.7 ± 15.0 g (mean ± SD) for the lateral rectus; 88.0 ± 15.4 g for the medial rectus; 61.3 ± 6.8 g for the inferior rectus; and 121.3 ± 38.5 g for the superior rectus. These values were higher than the reported values of 45–60 g measured in previous studies. In the previous studies, however, the EOM was detached from the globe and attached to a strain gauge, and, thus, there were no passive elastic forces from ocular connective tissue, resulting in lower values compared with the current study. The previous methods were also complex and not suitable for clinical measurement. Thus, the proposed method, which is non-invasive and mimics the conventional force generation test with a cotton-tipped swab, could facilitate the evaluation of active EOM tension, both clinically in strabismus management and in research into understanding its pathophysiology.

Identification and characterization of differentially expressed circular RNAs in extraocular muscle of oculomotor nerve palsy

BackgroundOculomotor nerve palsy (ONP) is a neuroparalytic disorder resulting in dysfunction of innervating extraocular muscles (EOMs), of which the pathological characteristics remain underexplored.MethodsIn this study, medial rectus muscle tissue samples from four ONP patients and four constant exotropia (CXT) patients were collected for RNA sequencing. Differentially expressed circular RNAs (circRNAs) were identified and included in functional enrichment analysis, followed by interaction analysis with microRNAs and mRNAs as well as RNA binding proteins. Furthermore, RT-qPCR was used to validate the expression level of the differentially expressed circRNAs.ResultsA total of 84 differentially expressed circRNAs were identified from 10,504 predicted circRNAs. Functional enrichment analysis indicated that the differentially expressed circRNAs significantly correlated with skeletal muscle contraction. In addition, interaction analyses showed that up-regulated circRNA_03628 was significantly interacted with RNA binding protein AGO2 and EIF4A3 as well as microRNA hsa-miR-188-5p and hsa-miR-4529-5p. The up-regulation of circRNA_03628 was validated by RT-qPCR, followed by further elaboration of the expression, location and clinical significance of circRNA_03628 in EOMs of ONP.ConclusionsOur study may shed light on the role of differentially expressed circRNAs, especially circRNA_03628, in the pathological changes of EOMs in ONP.

Effects of various extraocular muscle enlargement patterns on muscle diameter index in graves ophthalmopathy patients: a retrospective cohort study

Graves ophthalmopathy (GO) patients often undergo retrobulbar injection of glucocorticoids (GCs) as a common therapeutic approach. This study aimed to explore the impact of various patterns of extraocular muscle (EOM) enlargement on EOM changes following retrobulbar GCs injection in patients with GO. A retrospective analysis was conducted on GO patients who underwent retrobulbar GCs injections. Data pertaining to EOM diameter (EMD) and muscle diameter index (MDI) were collected from orbital computed tomography (CT) scans. The MDI change (ΔMDI) was calculated by comparing pre- and post-injection MDI values. The relationship between each pre EMD/MDI and ΔMDI was assessed using univariate and multivariate logistic regression analysis. A total of 68 patients with GO were included in this study, accounting for 118 eyes. After retrobulbar injections of GCs, 84 eyes showed a decrease in the MDI, while 34 eyes exhibited an increase in MDI. A threshold effect was observed in the relationship between medial pre EMD/MDI and ΔMDI. When the medial pre EMD/MDI was less than 0.28, a higher medial pre EMD/MDI was associated with a smaller ΔMDI (β = − 25.21, p = 0.0175). However, when the medial pre EMD/MDI was greater than 0.28, no significant association was found between pre EMD/MDI and ΔMDI. There was a negative correlation between medial + lateral pre EMD/MDI and ΔMDI (β = − 11.76, p < 0.0189). A higher medial + lateral pre EMD/MDI was associated with a greater decrease in MDI. Additionally, there was a positive correlation between superior rectus muscle-levator complex (SRLC) pre EMD/MDI and ΔMDI (β = 11.92, p = 0.040). The higher the value of SRLC pre EMD/MDI, the greater the ΔMDI. There was an association between pre EMD/MDI and changes in EOMs after retrobulbar injection of GCs in GO patients. In patients with predominantly enlarged medial rectus muscles and severe degrees of enlargement, retrobulbar injection of GCs should be assessed for its benefit; a combination of medial and lateral rectus muscle enlargement is beneficial for the shrinkage of EOMs following retrobulbar injections; the involvement of the SRLC rectus muscle may be a disadvantageous pattern of shrinkage of EOMs following retrobulbar injections.Trial registration This study is retrospectively registered. We have registered this study with the Chinese Clinical Trials Registry (www.chictr.org.cn, registration number: ChiCTR2200063429).

THU668 Euthyroid Graves’ Ophthalmopathy: Case Series

Abstract Disclosure: S.S. Alfadl: None. A.A. Asiri: None. A.A. Jammah: None. O. Alsagheir: None. Introduction: Graves’ ophthalmopathy is an autoimmune disorder that affects the eyes, characterized by swelling, proptosis, lid lag, inflammation and eyelid retraction. A significant proportion of cases are associated with thyrotoxicosis and positive serum TSH receptor antibody tests. Case Description: We present a case series of euthyroid Graves’ ophthalmopathy in patients with a negative TSH receptor antibody. The first case is of a 37-year-old lady who was recently diagnosed with idiopathic intracranial hypertension due to history of recurrent headaches and was found on CT brain to have an incidental empty sella syndrome and findings highly suggestive of thyroid associated orbitopathy. A dedicated MRI orbit showed bilateral mild proptosis with bilateral medial and inferior recti thickening, sparing the tendinous insertion. The involved extraocular muscles show mild peripheral high T2 signals and minimal enhancement on post gadolinium images. The enlarged extraocular muscle demonstrates diffusion restriction with low Apparent Diffusion Coefficient (ADC) value. Clinically, the patient did not exhibit any symptoms of hyperthyroidism or hypothyroidism. She did not notice any changes in her eyes’ appearance, nor any changes in vision or double vision. On examination, she had mild proptosis, no restriction of extraocular movement or provoked double vision. Consequently, she was referred to Ophthalmology for further management. Investigations included a pituitary panel which did not reveal any abnormalities and a thyroid panel which revealed that she was biochemically euthyroid with a negative TSH receptor antibody test. The second case is of a 24-year-old male who is medically free and initially visited the ophthalmology clinic complaining of double vision, without any additional ophthalmic complaints. He was subsequently referred to our care to rule out thyroid eye disease. Clinically, the patient had no indications of thyroid dysfunction. Upon examination, he exhibited severe right eye proptosis with dystopia and early left eye proptosis. CT orbit showed swelling of the right-sided superior rectus, medial rectus, lateral rectus and left-sided superior rectus muscles. The left-sided superior rectus muscle was abutting the optic nerve. Nevertheless, all tendons were spared. Biochemically, he was euthyroid with unremarkable laboratory results. Conclusion: These findings provide insight into the clinical presentation of euthyroid Graves’ ophthalmopathy in patients without thyrotoxicosis or detectable circulating levels of TSH receptor antibodies. Thus, suggesting that thyroid ophthalmopathy might present earlier than Graves’ disease and even earlier than the presence of TSH receptor antibodies. We conclude that a high index of suspicion and proper follow up is recommended in similar patients for the development of Graves’s disease. Presentation: Thursday, June 15, 2023

FRI554 Pretibial Myxedema Associated With Hashimoto Thyroiditis Treated With Teprotumumab

Abstract Disclosure: E.M. Niedzialkowska: None. B. Ajaz: None. A. Pokharel: None. Introduction: Pretibial myxedema (PTM) is a localized thyroid-associated dermopathy characterized by local thickening of the skin of the lower extremities. It mostly develops after the onset of thyroid eye disease (TED). Majority of the cases are associated with Graves disease (GD) but infrequently it can occur in Hashimoto thyroiditis (HT) in the presence of thyroid stimulating immunoglobulins (TSIs). Orbital fibroblasts and the pretibial dermis share antigenic sites that underlie autoimmune thyroid disease. IGF-1 has been reported to potentiate the effects of TSH and TSI on TSHR signaling and fibroblast proliferation. Teprotumumab, a novel monoclonal antibody that blocks IGF-1R receptors, is registered for TED treatment. It is plausible it also improves outcomes in PTM through the same mechanism. Clinical case: 52 year old female reported to our Endocrinology clinic with proptosis and myxedema. The patient was diagnosed with hypothyroidism at the age of 21 and was on substitutional dose of levothyroxine, 125 mcg daily. She developed TED 7 years prior with bilateral exophthalmos with medial rectus muscle infiltration. She underwent 5 decompression surgeries and steroid courses due to concern for optic nerve compression. 4 years prior to the visit she developed bilateral, erythematous pitting edema of the lower extremities with involvement of the pretibial areas, ankles and toes and underwent excess left toe callus excision. Despite multiple courses of intralesional steroid injections and topical ammonium lactate use the patient reported persistent edema, pruritus, and restriction of motion. Laboratory results were significant for TSH of 1.73 uIU/mL (n 0.40 - 4.50 uIU/mL), TRAB &amp;gt;40 IU/L (0.00 - 1.75 IU/L), TSI 4.95 (n &amp;lt;0.10 IU/L), TPO antibody &amp;lt;=35 IU/mL, free ft3 2.5 pg/ml (1.7 - 3.7 pg/mL), free ft4 1.0 (0.7 - 1.5 ng/dL). The patient underwent thyroidectomy with pathology results consistent with Hashimoto thyroiditis (thyroiditis with thyroid follicles, Hurthle cell change, marked lymphoid and fibroadipose tissue). Following the procedure she experienced PTM and TED flare up. Subsequent orbital decompression and orbital steroid injections provided minimal improvement. The patient was started on Teprotumumab (8 infusions every 3 weeks) with marked improvement of orbitopathy (CAS reduction from 6/10 to 1/10) and significant reduction of lower extremity edema and rash. Conclusion: We present the case of Hashimoto thyroiditis associated with TED with PTM successfully treated with Teprotumumab. In TED, TSI binds to IGF-1R creating a complex that promotes orbital inflammation. Teprotumumab is believed to degrade antibody-receptor complex and downregulate fibroblast activation and glycosaminoglycans deposition. We postulate the same process may occur in dermal fibroblasts in the light of PTM improvement after teprotumumab treatment. Presentation: Friday, June 16, 2023

A Novel Technique Using Paretic Superior Rectus as a Globe Suspender for Monocular Elevation Deficiency.

Surgical innovations in strabismus provide opportunities to improve visual function, eye alignment, and cosmesis in rare pediatric ophthalmological conditions. Monocular elevation deficiency is a rare and multifactorial disease in which the affected eye is equally limited in terms of elevation during adduction and abduction. We aimed to present a novel procedure for the treatment of acquired monocular elevation deficiency using the paretic superior rectus muscle as a globe suspender to resolve hypotropia. We report the case of an eight-year-old girl with left eyelid ptosis and hypotropia two months after draining a left orbital abscess. Left inferior rectus muscle recession was performed at five years, with residual left hypotropia. Ophthalmological examination revealed a best-corrected visual acuity of 20/20 OD and 20/100 OS. Severe left eyelid ptosis and poor levator function were also observed. Extraocular motility showed left hypotropia of 40 prism diopters with the left superior rectus muscle under action (-4) in the adduction and abduction positions. A force duction test negative for restrictions on the inferior rectus muscle was performed intraoperatively. To reduce the risks of the Knapp procedure, the left superior rectus muscle was split into medial and temporal halves. Double-armed sutures were secured in half, and the halves were detached from the sclera. The medial and temporal halves were reattached anteriorly to the medial and lateral rectus insertions, respectively. Eight weeks after surgery, the patient had nine prism diopters of hypotropia in the primary gaze. Ten weeks after surgery, there was no change in visual acuity. In the cover test, the patient exhibited residual left hypotropia of nine prism diopters with a restriction (-4) of elevation in adduction and abduction. The parents were pleased with the satisfactory cosmetic outcomes, and postoperative clinical photographs of the patient showed improved hypotropia and persistent minimal elevation of the left eye during adduction and abduction. Superior rectus muscle splitting and vertical transposition to the medial and lateral rectus could be safer and simpler alternatives to the Knapp procedure and may offer a lower risk of anterior segment ischemia. Further studies are required to confirm these findings.

Characterization and Classification of Postoperative Cysts After Strabismus Surgery: Clinical, Histological, and Anterior Segment OCT Analysis in a Large German Cohort.

In this work, we provide a detailed characterization of a rare complication-subconjunctival cyst formation after strabismus surgery-in a large German cohort. We conducted a retrospective analysis of 822 consecutive patients who underwent strabismus surgery between 2015 and 2022. The patients received comprehensive eye and orthoptic examinations preoperatively, at 1day, and at 3months postoperatively. Cysts were analyzed with slit-lamp examination, anterior segment optical coherence tomography (AS-OCT), and histopathological subsumption. Nineteen cases of postoperative cysts were observed (2.3%), 12 of which underwent surgical revision. Clinical evaluation including slit-lamp and AS-OCT as well as histological analysis resulted in a classification of three types of cysts: type 1, which is a single hyporeflective cyst, type 2, which is a multilobular hyporeflective cyst, and type 3, a dense hyperreflective granulomatous-like cyst. Eta (η) correlation ratio analysis could show a correlation between time of clinical appearance and type of cyst (Eta = 0.63). Most cysts developed within 20days after surgery. Not only did cysts more frequently affect the medial rectus muscle, which in most cases underwent a shortening procedure (11/19 tucks, 4/19 resections) for intermittent exotropia (X(T)), but the cyst also formed earlier than in the lateral rectus muscle (Eta = 0.45). No correlation could be shown between the type of surgical procedure and time of cyst occurrence (Eta = 0.1). Patient age and cyst type correlated strongly (Eta = 0.47). The underlying type of strabismus did not correlate with the type of cyst observed. Our cases showed a strong positive correlation to the type of strabismus (X(T)), age (young patients), and the procedure (tuck/resection). We introduce a grading system for postoperative cysts after strabismus surgery, complementing histopathology and slit-lamp aspects with AS-OCT information.

Comparison of anterior segment optical coherence tomography and ultrasound biomicroscopy in localizing horizontal rectus muscle insertions.

To evaluate the viability and precision of measuring the distance from the limbus to extraocular muscle insertion using anterior segment optical coherence tomography (AS-OCT) and panoramic ultrasound biomicroscopy (UBM) before and after strabismus surgery. We recruited primary strabismus patients and measured the limbus-insertion distance by AS-OCT and UBM preoperatively, 2 weeks, and 1, 3, and 6 months postoperatively. Values were also measured using callipers intraoperatively before and after the planned procedures. Preoperative AS-OCT and UBM values were compared to intraoperative calliper measurements as the gold standard. Postoperative AS-OCT and UBM values were compared to the new postoperative limbus-insertion distance. The limit of agreement deemed clinically acceptable was defined as 1 mm. A total of 85 horizontal muscles of 40 patients, including 48 lateral rectus muscles and 37 medial rectus muscles, were analysed. Primary muscles could be successfully detected by AS-OCT (95%) and UBM (100%). At 2 weeks and 1, 3, and 6 months postoperatively, the new rectus muscle attachment site detection rate by AS-OCT was 6%, 32%, 80%, and 89%, respectively, and that by UBM was 24%, 60%, 85%, and 93%, respectively. The Bland-Altman plots revealed better consistency in pairs of AS-OCT, UBM, and calliper measurements of primary muscles than postoperative muscles. For primary muscles, 89% of AS-OCT measurements fell within the permissible range of surgical measurements (1 mm), but this dropped to 67% at 6 months postoperatively (P < 0.001). The accuracy of UBM measurements of primary muscles was 81%, and this decreased to 59% at 6 months postoperatively (P = 0.001). AS-OCT and UBM performed well in terms of imaging primary horizontal rectus muscles, but showed decreased accuracy and reproducibility in postoperative muscle measures.

Long-term Clinical Outcomes of Patients with Infantile and Refractive Accommodative Esotropia

Purpose: To compare the long-term clinical outcomes of patients with refractive accommodative esotropia (RAET) and infantile esotropia (IET).Methods: The medical records of patients with RAET and IET who were followed-up for more than 36 months were retrospectively analyzed. The RAET patients were prescribed spectacles to correct cycloplegic refraction and those with IET underwent bilateral, medial rectus recession. Visual acuity, refraction, the angle of esodeviation at far and near distances, and near-stereopsis were measured at each visit. The IET patients were divided into two groups by the time of surgery (before and after 24 months of age). Patients in both groups who underwent reoperations after diagnosis of partially accommodative esotropia (PAET) and recurrent IET during follow-up were analyzed.Results: Sixty-nine patients (40 with RAET and 29 with IET) were included. The follow-up period was 69.48 ± 28.41 months. At the final visit, the angles of esodeviation were 2.82 ± 5.46 prism diopters (PD) in the RAET group and 9.28 ± 8.37 PD in the IET group (&lt;i&gt;p&lt;/i&gt; &lt; 0.01). In IET patients who underwent surgery before and after 24 months of age, the angles of esodeviation were 4.62 ± 5.25 and 13.06 ± 8.63 PD and the median near-stereopsis values 60 and 140 arcsec at the final visit (&lt;i&gt;p&lt;/i&gt; &lt; 0.01, 0.03). Seven patients (17.5%) in the RAET group, and 2 (15.4%) and 10 (62.5%) IET patients who underwent surgery before and after 24 months of age, required reoperations (&lt;i&gt;p&lt;/i&gt; &lt; 0.01).Conclusions: RAET and IET patients who underwent surgery before 24 months of age exhibited better alignment and stereopsis at the final visit than those who underwent later surgery and the reoperation rate was lower.

Eye Muscle MRI in Myasthenia Gravis and Other Neuromuscular Disorders.

MRI of extra-ocular muscles (EOM) in patients with myasthenia gravis (MG) could aid in diagnosis and provide insights in therapy-resistant ophthalmoplegia. We used quantitative MRI to study the EOM in MG, healthy and disease controls, including Graves' ophthalmopathy (GO), oculopharyngeal muscular dystrophy (OPMD) and chronic progressive external ophthalmoplegia (CPEO). Twenty recently diagnosed MG (59±19yrs), nineteen chronic MG (51±16yrs), fourteen seronegative MG (57±9yrs) and sixteen healthy controls (54±13yrs) were included. Six CPEO (49±14yrs), OPMD (62±10yrs) and GO patients (44±12yrs) served as disease controls. We quantified muscle fat fraction (FF), T2water and volume. Eye ductions and gaze deviations were assessed by synoptophore and Hess-charting. Chronic, but not recent onset, MG patients showed volume increases (e.g. superior rectus and levator palpebrae [SR+LPS] 985±155 mm3 compared to 884±269 mm3 for healthy controls, p < 0.05). As expected, in CPEO volume was decreased (e.g. SR+LPS 602±193 mm3, p < 0.0001), and in GO volume was increased (e.g. SR+LPS 1419±457 mm3, p < 0.0001). FF was increased in chronic MG (e.g. medial rectus increased 0.017, p < 0.05). In CPEO and OPMD the FF was more severely increased. The severity of ophthalmoplegia did not correlate with EOM volume in MG, but did in CPEO and OPMD. No differences in T2water were found. We observed small increases in EOM volume and FF in chronic MG compared to healthy controls. Surprisingly, we found no atrophy in MG, even in patients with long-term ophthalmoplegia. This implies that even long-term ophthalmoplegia in MG does not lead to secondary structural myopathic changes precluding functional recovery.