Superior Oblique Research Articles

Z-split myectomy versus 7/8 posterior tenectomy for Brown syndrome

Brown syndrome is an extraocular muscle disorder that can cause motility restrictions, diplopia, and alternate head positioning. Multiple surgical techniques have been developed to resolve this problem. One technique, the superior oblique Z-split, lengthens the superior oblique tendon by partial-thickness cuts. Another technique, posterior 7/8 tenectomy, weakens the superior oblique while preserving its torsional action. This study aims to compare the outcomes of both surgeries.

Twenty-first century century superior oblique palsy meets artificial intelligence

Superior oblique (SO) palsy is a diagnostic consideration in most cases of cyclovertical strabismus. Participants will learn if they can beat artificial intelligence to distinguish actual SO palsy from another common diagnosis using only patient alignment measurements, in all cases objectively verified by imaging.

The preequatorial nasal superior oblique tendon syndrome

Abnormal superior oblique (SO) tendons have been characterized in both congenital and acquired palsies. The nasal insertion variant (class II) is rare but usually associated with a loose tendon in congenital cases. Iatrogenic anteriorization and nasal displacement of the SO can also occur following ocular surgery.

Unilateral four-muscle surgery for large monocular constant sensory exotropia

Recurrent exotropia is common following horizontal rectus muscle surgery for monocular constant sensory exotropia. Surgery is limited to avoid operating on the better-seeing eye. Simultaneous oblique weakening surgery may enhance the effect of the horizontal rectus muscles surgery by decreasing the abducting oblique force. We report the results of simultaneous inferior and superior oblique muscle weakening procedures combined with horizontal muscle recession/resection for large angle constant monocular sensory exotropia greater than 35Δ.

Automated Measurement of Ocular Movements Using Deep Learning-Based Image Analysis

Purpose Clinical assessment of ocular movements is essential for the diagnosis and management of ocular motility disorders. This study aimed to propose a deep learning-based image analysis to automatically measure ocular movements based on photographs and to investigate the relationship between ocular movements and age. Methods 207 healthy volunteers (414 eyes) aged 5–60 years were enrolled in this study. Photographs were taken in the cardinal gaze positions. Ocular movements were manually measured based on a modified limbus test using ImageJ and automatically measured by our deep learning-based image analysis. Correlation analyses and Bland-Altman analyses were conducted to assess the agreement between manual and automated measurements. The relationship between ocular movements and age were analyzed using generalized estimating equations. Results The intraclass correlation coefficients between manual and automated measurements of six extraocular muscles ranged from 0.802 to 0.848 (P < 0.001), and the bias ranged from −0.63 mm to 0.71 mm. The average measurements were 8.62 ± 1.07 mm for superior rectus, 7.77 ± 1.24 mm for inferior oblique, 6.99 ± 1.23 mm for lateral rectus, 6.71 ± 1.22 mm for medial rectus, 6.81 ± 1.20 mm for inferior rectus, and 6.63 ± 1.37 mm for superior oblique, respectively. Ocular movements in each cardinal gaze position were negatively related to age (P < 0.05). Conclusions The automated measurements of ocular movements using a deep learning-based approach were in excellent agreement with the manual measurements. This new approach allows objective assessment of ocular movements and shows great potential in the diagnosis and management of ocular motility disorders.

Course of the V3 segment of the vertebral artery relative to the suboccipital triangle as an anatomical marker for a safe far lateral approach: A retrospective clinical study

Background: The third segment of the vertebral artery (V3) is vulnerable during far lateral and retrosigmoid approaches. Although the suboccipital triangle (SOT) is a useful anatomical landmark, the relationship between V3 and the muscles forming the triangle is not well-described. We aimed to demonstrate the relationship between the V3, surrounding muscles, and SOT in clinical cases.Methods: Operative videos of patients with the vertebral artery (VA) and posterior inferior cerebellar artery (PICA) aneurysms treated with occipital artery-PICA bypass through the far lateral approach were examined. Videos from January 2015 to October 2021 were retrospectively reviewed to determine anatomy of the V3 and the SOT.Results: Fourteen patients were included in this study. The ipsilateral V3 was identified without injury in all patients using the bipolar cutting technique. The lateral 68.2% of the horizontal V3 segment, including the V3 bulge, was covered by the inferomedial part of the superior oblique muscle (SO). The medial 23.9% was covered by the inferolateral part of the rectus capitis posterior major muscle. The inferomedial part of the horizontal V3 segment is located within the SOT.Conclusion: Most of the V3, including the V3 bulge, were located beneath the SO and the inferomedial part of V3 located within the SOT. Elevation of the SO should be performed carefully using the bipolar cutting technique to avoid injury to the V3. To the best of our knowledge, this is the first description of the V3 relative to the SOT in the clinical setting.

Treatment of Dissociated Vertical Deviation by Combined Recession–Resection of the Superior Rectus Muscle versus Recession with Posterior Fixation Suture

Background: Management of dissociated vertical deviation (DVD) is still a matter of controversy in strabismus practice. Different surgical techniques are available, ranging from the weakening of the superior rectus or inferior oblique muscles to strengthening of the inferior rectus muscle, with variable success rates. Objective: To report the outcomes of correcting DVD by combined recession-resection of the superior rectus muscle and to compare the results with those of superior rectus muscle (SR) recession with posterior fixation sutures. Methods: The medical records of patients who had a surgical correction for DVD were retrospectively reviewed. Two groups of patients were identified; Group I (29 patients) was treated with the combined recession –resection of the SR and group II (37 patients) was treated by SR recession with posterior fixation sutures (Faden). Collected preoperative data included age, best-corrected visual acuity, presence of amblyopia, history of previous surgeries and angle of DVD. Operative data such as amount of SR recession and operative time were also extracted. The outcome measures taken at the final postoperative follow up visit included the surgical success rate which is identified as the percentage of patients with absent manifest DVD and the amount of residual latent deviation measured by prism cover test. Results: The mean follow-up period for all patients was 22.6 ±4.6 months. In the last follow-up visit, the surgical success rate was 76% in the combined recession-resection group and 73% in the faden group with no significant difference between both groups (p=0.8). No significant difference was found in the residual latent deviation in both groups as well. The recorded surgical time was significantly shorter in the combined recession- resection group (p&lt;0.001). The reported complications included mild, temporary limitation of elevation without hypotropia in 5 patients (2 in group I (7%) and 3 patients in group II (8%)) with no significant difference between both groups (p=0.8). Conclusion: Combined recession-resection of SR is as effective as SR recession with posterior fixation suture in the management of DVD with the advantages of easier technique and less surgical time.

Primary Diffuse Large B-Cell Lymphoma of the Frontal Sinus.

A 73-year-old male presented with 6 months of right upper eyelid swelling and 3 weeks of progressive binocular diplopia. Examination was notable for right eye vision of 20/70, near-complete motility restriction, proptosis of 4 mm, complete ptosis, periorbital edema, and conjunctival injection (Fig. 1A); slip lamp and dilated examination were otherwise normal. CT demonstrated a large, homogenous, expansile mass extending from the right frontal sinus into the superior extraconal orbit. He was scheduled for surgery and placed on a preoperative prednisone taper. In the intervening month, he experienced rapid progression of disease, with severe periorbital edema and hemorrhagic chemosis (Fig. 1B). He underwent right anterior orbitotomy and frontal sinus exploration, total ethmoidectomy, and maxillary antrostomy. Orbital exploration revealed a firm, grey-tan-colored tumor invading the superior orbit (Fig. 1C). Histopathology revealed CD5 positive diffuse large B-cell lymphoma with MYC gene rearrangement. Staging work-up, including MRI (Fig. 2, top), revealed an interval increase in lesion size, with encasement of the right superior, medial, and lateral rectus muscles, superior oblique muscle, and optic nerve. He was diagnosed with stage IE diffuse large B-cell lymphoma of the frontal sinus and right orbit. He completed 3 cycles of rituximab, cyclophosphamide, hydroxydaunorubicin, oncovin, prednisone and consolidative radiotherapy. Follow-up nasal endoscopy, positron emission tomography, and MRI (Fig. 2, bottom) showed complete metabolic response. Primary frontal sinus lymphoma is a rare entity, typically manifesting with mass effect or cranial nerve palsy. It may mimic benign lesions, such as mucoceles, on imaging. Timely recognition and multidisciplinary management are crucial to reduce associated morbidity.FIG. 1.: From initial presentation (A) to day of surgery (B), the patient experienced rapid progression of disease, with severe periorbital edema and hemorrhagic chemosis. Orbital exploration (C) revealed a firm, grey-tan-colored tumor invading the superior orbit.FIG. 2.: Pre-chemoradiation, magnetic resonance imaging (top) showed a large, expansile mass extending from the right frontal sinus into the superior extraconal space, with encasement of multiple extraocular muscles and the optic nerve. Post-treatment imaging (bottom) demonstrated complete metabolic response.

Effects of myostatin gene knockout on porcine extraocular muscles

Myostatin (MSTN), a negative regulator of skeletal muscle mass, is not well known in extraocular muscles (EOMs). EOMs are specialized skeletal muscles. Hence, in this study, the effect of MSTN on the superior rectus (SR) and superior oblique (SO) of 2-month-old MSTN knockout (MSTN−/−) and wild-type (WT) pigs of the same genotype was investigated. SR (P < 0.01) and SO (P < 0.001) fiber cross-sectional areas of MSTN−/− pigs were significantly larger than those of WT pigs. Compared with WT pigs, MSTN−/− SO displayed a decrease in type I fibers (WT: 27.24%, MSTN−/−: 10.32%, P < 0.001). Type IIb fibers were higher in MSTN−/− pigs than in WT pigs (WT: 30.38%, MSTN−/−: 62.24%, P < 0.001). The trend in SR was the same as that in SO, although the trend in SO was greater than that in SR. The expression of myogenic differentiation factor (MyoD) and myogenic (MyoG) showed a significant increase in MSTN−/− SO (about 2.5-fold and 2-fold, respectively at the gene expression level, about 1.5-fold at the protein level) compared with WT pigs. MSTN plays an important role in the development of EOMs and regulates the muscle fiber type by modulating the gene expression of MyoD and MyoG in pigs.

Masquerading Superior Oblique Palsy

We evaluated patients with hypertropia compatible with a diagnosis of superior oblique (SO) palsy to ascertain whether the 3-step test (3ST) can distinguish SO atrophy characteristic of trochlear nerve pathology from masquerading conditions. Prospective cross-sectional study. In an academic practice, we performed quasi-coronal plane, surface coil magnetic resonance imaging in 83 patients clinically diagnosed with SO palsy. We evaluated alignment, SO cross-sectional area, SO contractility, and rectus muscle pulley positions. A total of 57 patients with mean age 39 years (SD = 21 years) had unilateral SO palsy manifested by SO atrophy (22 congenital and 35 acquired). There was normal SO size in 26 patients with an average age of 39 years (SD =16 years) considered masquerades (8 congenital and 18 acquired). Maximum palsied SO cross-section averaged 9.5 ± 3.8 mm2, less than 18.4 ± 3.9 mm2 contralaterally (P < 10-24). In masquerades, maximum hypertropic SO cross-section was 20.7 ± 3.1 mm2, which was not different from the hypotropic SO or the contralesional muscle in SO palsy. Head tilt testing in masquerades was indistinguishable from SO palsy. In SO palsy, central hypertropia averaged 13.2 ± 9.4Δ, increasing to 21.1 ± 14.0Δ in ipsilateral tilt, and decreasing to 4.3 ± 5.3Δ in contralateral tilt. In masquerades, central hypertropia averaged 13.1 ± 8.7Δ, and was 17.7 ± 11.1Δ in ipsilateral and decreasing to 4.9 ± 5.1Δ in contralateral tilt. Upright hypertropia was larger at 17.7 ± 9.9Δ in congenital than 12.0 ± 8.4Δ in acquired SO palsy (P = 0025) but was indistinguishable from congenital masquerades. Contractile change in SO cross-section was bilaterally similar in masquerades. Relevant coordinates of rectus pulleys were similar bilaterally in masquerades. The 3ST pattern characteristic of unilateral SO palsy may be mimicked in all respects by masquerades.

Discordant horizontal-torsional nystagmus: a sign of posterior semicircular canal dysfunction.

In central as well as peripheral vestibular lesions, right-beating horizontal nystagmus is almost always associated with clockwise (top poles of the eyes beating to the right ear) torsional nystagmus when observed and vice versa (concordant nystagmus). This study aimed to determine the etiologies and mechanisms of horizontal and torsional nystagmus beating in the opposite directions (discordant nystagmus). We reviewed the medical records of 16 consecutive patients with discordant horizontal-torsional nystagmus who had been evaluated at the dizziness clinics of Seoul National University Bundang Hospital (n = 11, from March 2003 to March 2021) and Korea University Medical Center (n = 5, from March 2019 to March 2021). The underlying etiologies included inferior vestibular neuritis (n = 7), Meniere's disease (n = 4), internuclear ophthalmoplegia (n = 3), medullary hemorrhage (n = 1), and normal pressure hydrocephalus (n = 1). The torsional nystagmus decreased during the gaze in the same direction (for instance, during rightward gaze in clockwise nystagmus) and increased during the gaze in the opposite direction. Head-impulse tests (HITs) were positive for the ipsilesional posterior canal (PC) in all 11 patients with unilateral peripheral vestibulopathy and two of the three patients with unilateral central vestibulopathy. Discordant horizontal-torsional nystagmus may be observed in peripheral as well as central lesions. Given the findings of HITs and modulation of spontaneous nystagmus during lateral gazes, discordant horizontal-torsional nystagmus may be ascribed to selective damage of the excitatory or inhibitory pathway from the PC that innervates the ipsilateral superior oblique and contralateral inferior rectus muscles.

Three-dimensional morphological analysis of quadrilateral plate fragments in associated both-column acetabular fractures.

To investigate whether the fracture morphology of quadrilateral plate (QP) fragments is associated with the anterior and posterior columns in associated both-column (ABC) fractures. Three-dimensional computed tomography data of 100 ABC fractures treated at our hospital from August 2016 to August 2019 were retrospectively analyzed using Mimics and 3-matic software. The distribution of fracture lines was described using the fracture mapping technique. One fragment presented on the QP was confirmed in 88% of the patients. The QP fragments' fracture lines were divided into the anterior oblique (AO), superior posterior oblique (SPO), and mid-posterior oblique (MPO) lines, occurring in 100, 86, and 8 cases, respectively. AO lines were distributed along the arcuate line. SPO lines were continuations of the AO lines, which were distributed to the posterior column from the greater sciatic notch to the lesser sciatic notch. MPO lines were involved in the QP's central area. A simple fracture was found at the proximal AO and SPO lines in 80% and 86% of all displaced fractures, respectively. AO lines distal to the superior rim of the acetabula were confirmed to be comminuted fractures in 32% of all cases. In ABC fractures, there was only one QP fragment in nearly 90% of all cases. The QP fractures were mainly present in the QP's peripheral area. More than 80% of the fracture patterns on the cephalic side of the QP were simple. The reduction and internal fixation of QP fractures in ABC fractures should be in the cephalic region.

3D Printed Schematic Model for Extraocular Muscles teaching

There are many difficulties a student or educator can present in the anatomy course. Technological advances and availability of new tools have provided alternatives to improve the learning method.A 3D model of an orbit and ocular globe (OG) was designed and 3D printed. It consisted of a roof, floor, medial and lateral walls, and a posterior wall. The superior and inferior orbital fissures were represented, as well as the common tendinous ring (Zinn's) and the optic canal from which a cylindrical axis extends in a 45° angle, representing the optic nerve (ON). At the end of this axis, a sphere an enarthrosis sphere simulates the OG. The medial wall is parallel to the OG’s axis, while the lateral wall is almost parallel to the ON’s axis. The OG was formed with polygons to allow better perception of the movements. The center of the sphere attached to the ON matches the center of the OG, resulting in the OG rotating without moving within the orbit.Six holes were made in the OG, in which elastic threads were placed. In the anterior half of the OG, a hole for the superior, inferior, medial and lateral surfaces was made, corresponding to the insertions of the superior rectus (SR), inferior rectus (IR), medial rectus (MR), and lateral recti muscles (LR) respectively. On the lateral surface of the posterior half of the OG, a hole in the superior region was made for the insertion of the superior oblique (SO) and another in the inferior region for the insertion of the inferior oblique (IO). The four rectus muscles originate from the annulus of Zinn, and represented with holes that cross the posterior wall of the orbit in the common tendinous ring at the four points of insertion.In the medial wall of the orbit, at the superior anterior corner, a trochlea was made, through which the thread representing the SO passes and is anchored to the posterior wall through a hole that is superior to the hole for the SR. On the same wall, but in the interior anterior corner of the orbit, we designed a hole to anchor the thread that represents the IO. The angles between the axes of the oblique muscles, recti muscles, and the axis of the OG were kept as close to reality as possible. In the model, the axis between the recti muscles and the OG’s is 20° (human orbit is 23°) and between the oblique muscles and the OG’s is 70° (human orbit is 51°).The design allows an internal rotation when tightening the threads that are inserted in the superior half of the OG (SR, SO); if the inferior half are tightened (IR, IO), it causes an external rotation; if the recti are tightened, adduction occurs (except for the LR); if those representing the obliques and the LR are tightened, an abduction occurs; if those inserted in the anterior half of the OG (SR, IR, MR, LR) are tightened, the movement corresponding to its name is produced, and if those inserted in the posterior half are tightened, the movement occurs opposite to what their names indicate (SO, IO).The model is effective and makes learning easier. Student perception has not been surveyed yet. Future version may improve the angle between the oblique’s and the OG’s axis. Pathological finding can also be exemplified.

The Trochlear Nerve: Anatomy and Pathology

The trochlear is a thin nerve that provides motor innervation to the superior oblique muscle and, usually, is not identified in conventional magnetic resonance imaging (MRI). It can be affected by congenital disorders, trauma, inflammatory and neoplastic conditions. This article aims to review the trochlear nerve's normal anatomy, functions, and imaging technique.

Long-term ophthalmological outcomes in patients with anterior plagiocephaly managed with a fronto-orbital advancement procedure

Anterior plagiocephaly results from early fusion of a unilateral coronal cranial suture, which affects 1/10,000 infants at birth and can be associated with ophthalmological complications. The study aimed to evaluate the frequency of oculomotor disorders and refractive errors in children with non-syndromic anterior plagiocephaly. Patients with anterior plagiocephaly undergoing surgery using a fronto-orbital advancement technique were included in this retrospective study between 2011 and 2017. The following data were collected: cycloplegic refraction in diopters (D), best-corrected visual acuity, manifest strabismus in primary position, ocular motility, head tilt in primary position, slit-lamp and fundus examination. The refractive errors were determined by autorefraction after cycloplegia with cyclopentolate. Among the sixteen patients included, hyperopia >2.5D was found in 10 patients, astigmatism >1D in 10 patients and anisometropia >1D in 7 patients. Astigmatism was contralateral to the synostosis in 7 cases. In total, significant refractive errors were found in 92.9%. Amblyopia was found in 33.3% patients. Strabismus was found in 11 patients, most frequently combined horizontal and vertical, of which 4 required strabismus surgery. The most frequent vertical deviation was ipsilateral hypertropia in 54.5%. We found superior oblique muscle limitation in 3 patients. Optic disc pallor was found in 2 patients. In the years following fronto-orbital advancement for non-syndromic anterior plagiocephaly, refractive errors and oculomotor disorders are frequently encountered, mainly contralateral astigmatism and strabismus with both horizontal deviation and ispilateral hypertropia.

The Oculomotor Nerve: Anatomy and Pathology

The oculomotor nerve is the third cranial nerve, exiting the brainstem in the medial border of the cerebral peduncle, from where it crosses straight to the superior orbital fissure. It is a purely motor nerve responsible for the innervation of all the extraocular muscles, except the superior oblique and lateral rectus muscles. It also has parasympathetic pre-ganglionic fibers, responsible for the innervation of sphincter pupillae and ciliary muscles. Magnetic resonance imaging (MRI) is the best imaging exam to evaluate patients with clinical signs of third cranial nerve palsy. The oculomotor nerve can be affected by several diseases, such as congenital malformations, trauma, inflammatory or infectious diseases, vascular disorders, and neoplasms. This article aims to review the oculomotor nerve anatomy, discuss the best MRI techniques to evaluate each nerve segment, and demonstrate the imaging aspect of the diseases that most commonly affect it.

Clinical Characteristics and Surgical Outcomes of Patients with Congenital Fibrosis of the Superior Rectus Muscle.

IntroductionCongenital fibrosis of superior rectus muscle (CFSRM) is extremely rare and a difficult condition to manage surgically. The purpose of this report is to summarize the clinical characteristics of patients with CFSRM and analyze the effects of its surgical management.MethodsRecords of nine CFSRM patients were retrospectively reviewed and their clinical features including age, gender, visual acuity, refraction, ocular alignment, ocular motility, surgical method employed and final outcomes were analyzed.ResultsAll cases were monocular. There were four cases (44.4%) coexistent with fibrosis of the levator palpebrae muscle and three (33.3%) with fibrosis of the superior oblique muscle. Eight cases (88.9%) presented with hypertropia, and one case showed mild hypotropia. Horizontal deviation was presented in six cases (66.7%). Surgical approaches included either superior rectus recession/tenotomy with or without traction suture; superior rectus recession and inferior rectus resection; or adhesion separation of superior rectus and levator palpebrae muscles. Excellent surgical outcomes were obtained in five cases (55.6%), good in two (22.2%), and poor outcomes were reported for two cases (22.2%). One patient (11.1%) underwent a second surgery.ConclusionCFSRM was found to be mainly unilaterally infected, mostly manifesting as hypertropia, and was often associated with fibrosis of the levator palpebrae or superior oblique muscle. Weakening procedures of the superior rectus muscle were the preferred surgical technique. However, success rates were relatively low for CFSRM.

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

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

Normative orbital measurements in an Australian cohort on computed tomography

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

Modified Harada-Ito Procedure with Intraoperative Adjustable Sutures Using a Mendez Ring for Excyclotorsion

Purpose: We report a case of using a modified Harada-Ito procedure with intraoperative adjustment via a Mendez ring in a patient with bilateral superior oblique palsy, resulting in satisfactory postoperative outcomes.Case summary: A 47-year-old male patient presented with bilateral diplopia after cerebral hemorrhage. Bilateral superior oblique palsy was diagnosed, and double Maddox rod tests confirmed 20° of excyclotorsion in both eyes. After 6 months of observation, surgical correction was attempted. To check the amount of cyclodeviation, a modified Harada–Ito procedure was performed on the superior oblique muscle after marking at the 6 and 12 o'clock positions of the corneal limbus. Following the procedure, a Mendez ring was placed on the limbus to check for the amount of incyclotorsion. Thirty degrees of incyclotorsion was aimed at both eyes, and a 5-mm resection of the right superior oblique tendon was performed for additional correction. There was no complaint of diplopia at 6 months postoperatively, and no deviation was observed.Conclusions: A modified Harada-Ito procedure with intraoperative adjustment using a Mendez ring effectively corrected excyclotorsion with torsional diplopia.