Study 3: Anterior segment optical coherence tomography-guided surgical approach in slipped medial rectus muscle

Purpose: To discuss the novel swept?source anterior segment optical coherence tomography (SS?ASOCT)?guided surgical approach in slipped medial rectus muscles. Methods: Prospectively (between February 2020 and July 2022), six patients with a clinical suspicion of slipped medial rectus muscle were recruited. After complete ophthalmic and orthoptic evaluation, the missing medial rectus muscle is screened using Anterior Segment Optical Coherence Tomography (ASOCT). In presence of a traceable muscle, its morphology, depth, and distance from a fixed anatomical landmarks were noted; in its absence, the status of other recti was noted. Intraoperatively, the features were confirmed and the intended intervention was performed. Results: The mean age of six patients was 25.66 ± 9.72 years, two with surgical trauma and four with penetrating trauma (66.66%). In five patients, the ASOCT traced the slipped medial rectus muscle successfully (83.33%); intraoperatively, the same was confirmed (within 1–2 millimeters) with favorable outcomes. ASOCT made a significant contribution in all subjects by reducing the number of interventions and muscle surgeries. Conclusions: In eyes with slipped medial rectus muscle, especially those which are within a finite distance from the angle can be traced using ASOCT. This approach impacts the outcomes in many ways

Eyeball Displacement into Ethmoid Sinus with Good Visual Restoration

PURPOSE: To report a case of eyeball displacement into the ethmoid sinus followed by early surgical intervention and good visual recovery. CASE SUMMARY: A 46-year-old female visited our hospital after she injured the right side of her face. Her visual acuity could not be measured and computed tomography revealed displacement of the right eyeball into the ethmoid sinus, as well as right medial orbital wall fracture and rupture of the right medial rectus muscle. She underwent surgical reduction of the herniated eyeball and surgical correction of the medial orbital wall fracture within 20 hours after the accident. Eighteen months after the surgery, visual acuity of the right eye improved from light perception to 20/28, and her color vision and visual field of the right eye improved to normal range. CONCLUSIONS: Displacement of the eyeball in the orbital wall fracture is very rare, and eyeball displacement into the ethmoid sinus is even rarer. We achieved good visual outcome through early surgical intervention. The early anatomical reduction of the displacement and wall fracture may promote improved final visual outcome in other similar cases.

The Clinical Observation of Hydroxyapatite Prosthesis Implantation through Lateral Rhinotomy Approach on the Orbit / 昆明医科大学学报

Objective To observe exposure rates of hydroxyapatite artificial eye by comparing hydroxyapatite prosthesis implantation through lateral rhinotomy approach on the orbit and traditional sclera shell hydroxyapatite prosthesis implantation.Methods After eye content was enucleated at postoperative stage I,75 patients received hydroxyapatite prosthesis implantation,among which 26 received direct sclera shell prosthesis implantation (group A) and 49 received implantation through lateral rhinotomy approach on the orbit (group B).During postoperative follow-up from 6 months to 5 years,exposure rates of hydroxyapatite artificial eye under two operation ways were observed and analyzed by x 2 test.Results According to observation,8 cases were exposed in the group A,and 2 cases were repaired by fascia and conjunctival repair.Six cases were healed by prosthesis and sclera replacement.In group B,only 1 case was exposed slightly and recovered after simple conjunctival repair.The incidence of the eye exposure rate using two kinds of operation methods in group A is significantly higher than that in group B (P ＜ 0.05) The difference was statistically significant.Conclusion The exposure of hydroxyapatite artificial eye can be effectively avoided and postoperative complications can be reduced by hydroxyapatite prosthesis implantation through lateral rhinotomy approach on the orbit among patients with severe eyeball ruptures,painful eyeballs of no light perception and atrophy eyes.

A Case of Pediatric Medial-Orbital Wall Fracture with Extraocular Muscle Entrapment

PURPOSE: To report a case of pediatric medial wall blowout fracture with entrapment of medial rectus muscle which can be easily misdiagnosed as a cerebral lesion. CASE SUMMARY: A 16-year-old male visited our clinic with headache, severe restriction of his right eye movement, and diplopia after a head injury due to falling occurring 1 day before evaluation. The patient was inebriated at the time of the accident and could not recall the event but occipital hematoma was palpable. Periorbital ecchymosis or edema was not observed with minimal soft tissue injury except mild conjunctival injection on slit-lamp examination. The patient had an 18 prism diopter exodeviation at primary position and severe medial and mild lateral gaze limitation in his right eye. Brain magnetic resonance imaging (MRI) showed no specific cerebral findings although trapdoor orbital medial wall fracture with incarceration of soft tissue and medial rectus muscle at the medial wall fracture site of his right eye was observed. Within 48 hours from the first evaluation, the blowout fracture was repaired and 50 days postoperatively, right eye gaze limitation and diplopia were nearly recovered. CONCLUSIONS: A case of pediatric blowout fracture with uncertain injury location, periocular ecchymosis, or edema absent could be misdiagnosed as a cerebral lesion. If a pediatric patient is experiencing gaze limitation, diplopia, nausea, or vomiting after trauma, neurological examination as well as evaluation for blowout fracture should be performed.

Pulley tissues maintain the mechanical advantage of extraocular muscles under eye adduction: A simulation study / 医用生物力学

Objective To study the biomechanical effect from pulley tissues of extraocular muscles on super adduction of the eye. Methods By the coordinate parameters of extraocular muscles reported in the literature and based on the mechanical equilibrium of eye movement, two mechanical models, active pulley model and non pulley model (as control), were established to simulate eye adduction in the range of 30°-45°. Results For the contribution of medial rectus muscle, the non pulley model produced more force than the active pulley model to control eye adduction, and its corresponding force value increasingly exceeded the physiologically safe threshold (0.5 N). At the maximum simulative adduction of 45°, the force of medial rectus obtained by active pulley model and non pulley model was 0.508 N and 0.782 N, respectively, and the latter was 56% greater than the safe threshold. For controlling eye adduction, the active pulley model consumed much less energy than the non pulley model. Conclusions Due to the existence of pulley tissues, extraocular muscles could control eye adduction by consuming less biological energy and reinforce the ocular derivation. In addition, with the active pulley, the medial rectus muscle could maintain its mechanical advantage under super adduction of the eye.

The Effect of Unilateral Medial Rectus Muscle Resection in Patients with Recurrent Exotropia

PURPOSE: To investigate the effect of unilateral medial rectus muscle resection for recurrent exotropia after bilateral lateral rectus muscle recession for intermittent exotropia METHODS: A retrospective analysis was made of thirtypatients who underwent unilateral medial rectus resection for recurrent exotropia. All had prior bilateral lateral rectus recession for intermittent exotropia. Data were collected for age, the preoperative deviation, the postoperative deviation at 2 weeks, 3 months, 6 months and the last visit, and the amount of medial rectus resection performed. RESULTS: The average preoperative deviation was 27.0+/-3.6 PD. After unilateral medial rectus resection, average deviation at distance was 2.8 PD at postoperative 2 weeks, 4.5 PD at 3 months, 5.1 PD at 6 months and 5.8 PD at last visit. The average deviation corrected per millimeter of medial rectus resection was 3.53+/-0.17 PD/mm. CONCLUSIONS: Considering that deviation angles of recurrent exotropia is smaller than those of primary surgery and the possibility of saving the other medial rectus muscle, unilateral rectus muscle resection could be effective surgical method for recurrent exotropia.

Vertical Rectus Muscles Transposition in Large Exotropia with Medial Rectus Muscle Transection Following Endoscopic Sinus Surgery

PURPOSE: To evaluate the effect of transposition procedures on the vertical rectus muscle (VRM) in the patients who underwent a medial rectus muscle (MR) transection after endoscopic sinus surgery (ESS). METHODS: In 4 patients with exotropia (XT) and a lack of adduction after ESS, orbital CT or MRI revealed a complete transection of the midportion of the MR. Full-tendon VRM transposition was performed within 3 months after injury (early surgery) in 2 patients with 40delta XT. Two patients with 70delta and 85delta XT underwent an X-type augmented Hummelsheim procedure, which involved pulling each half-tendon and crossing it through the undersurface of the severed MR to the other end of the MR insertion, concurrently with an ipsilateral lateral rectus (LR) recession 11 months and 36 months after ESS, respectively. The adduction deficits were divided into -1 through to -8. The patients were followed up for more than than 1.5 years. RESULTS: Postoperatively, 3 patients showed orthophoria and no diplopia in the primary position. The adduction deficits improved to -3.5 or -4. One patient who underwent an X-type augmented Hummelsheim procedure showed a residual XT of 25delta. CONCLUSIONS: VRM transposition is effective in correcting a large XT secondary to a MR transection after ESS. When a longstanding large-angle XT with severe contracture of the ipsilateral LR and massive scarring of the adjacent tissues is present, the X-type augmented Hummelsheim procedure coupled with an ipsilateral LR recession had an augmenting effect.

Injury of the Medial Rectus Muscle by Using a Microdebrider During Endoscopic Sinus Surgery : A Case Report / 영남의대학술지

A microdebrider is increasingly used in endoscopic sinus surgery. Although it has many advantages over conventional instruments, it has been associated with severe complications. We treated a case of rupture of the left medial rectus muscle after use of a microdebrider during endoscopic sinus surgery in a 50 year-old female patient who complained of binocular diplopia and exotropia. The patient showed marked limitation on adduction and about 40 prism diopters of left exodeviation. The orbital computed tomography showed a bony defect at the left medial orbital wall, and injury of the medial rectus muscle. The exodeviation was corrected after ophthalmologic surgery. We report a case of the rupture of the medial rectus muscle after use of a microdebrider during endoscopic sinus surgery and review the medical literature.

A Case of Convergent Strabismus Fixus with Invisible Cornea

PURPOSE: We report an example of successful operation of rare convergent strabismus fixus, which had previously been mistaken for orbital tumor in private clinics because of severe adduction with unseen cornea. METHODS: A 57-year-old woman had convergent strabismus fixus with inward deviation of the left eye that had gradually progressed since she was around 40. Her cornea was buried in the intraorbital rim. An eye movement examination revealed that the eyeball was fixed to the internal part and that eyeball movement was impossible in all directions. When the forced duction test was performed, strong resistance was shown in all directions when abducted. During surgery, the medial rectus muscle was disinserted after resection of 3.0 mm for the left eye, and lateral rectus muscle tucking of 11.0 mm for the left eye was conducted. Since there was resistance in the inferior oblique muscle by the forced duction test during the operation, inferior oblique muscle myectomy of 4.0 mm was simultaneously performed. RESULTS: In the forced duction test implemented immediately after the operation, resistance subsided considerably and eye movement was shown in all directions, with cosmetically satisfactory results. Optic atrophy was found in the fundus examination after the operation. CONCLUSIONS: Convergent strabismus fixus, which recurs frequently and causes severe limitation of eye movement, was changed from the primary position to orthophoria by medial rectus muscle resection with disinsertion and lateral rectus muscle tucking. The eye movement disorder was improved and a satisfactory result was obtained.

The Long Term Surgical Outcome after Bilateral Medial Rectus Muscle Recession in Partially Accommodative Esotropia

PURPOSE: To study the correlation between the outcome of the early postoperative period and the long-term outcome after surgery for partially accommodative esotropia. METHODS: The medical records of total 85 patients with partially accommodative esotropia, who underwent bilateral medial rectus muscle recession, and were followed-up at least 6 months, were retrospectively reviewed. The results were analyzed at 1 month, and 1 and 4 years after surgery. RESULTS: Of the 85 patients, 67 (78.8%) revealed postoperative deviation of less than 10 PD, 11 (12.9%) and 7 (8.2%) esotropia and exotropia more than 11 PD, respecrively, 1 month after surgery. At 1year postoperatively, 59 (77.6%), 8 (10.5%) and 9 (11.8%) showed acceptable deviation, undercorrection, and overcorrection, respectively. 4 years after surgery, 26 (81.2%) and 3 (9.4%) each showed acceptable deviation, undercorrection, and overcorrection, respectively. The results showed a tendency to become exotropic during the 4 years after surgery. CONCLUSIONS: In partially accommodative esotropia, it is essential that orthotropia or minimal esotropia should be present in the early postoperative period in order to obtain a good binocular alignment as the long term result. It is recommended that overcorrection be avoided in early postoperative exotropia.

Treatment of Exotropia Caused by Lost Medial Rectus Muscle

PURPOSE: We report three patients with large angle exotropia had lost medial rectus muscle (MR) and who attained good alignment postoperatively. METHODS: Patient 1 was a 51-year-old female with a history of strabismus surgery done at 10 years of age. Exotropia of 80 prism diopter (PD) gradually developed with limitation of adduction in the right eye. Patient 2 was a 52-year-old male with fixed exotropia of 95 PD in his left eye, which became blind after a severe contusion injury. The third patient was a 46-year-old male who had MR of the right eye cut during endoscopic sinus surgery. Severe limitation of adduction followed with exotropia of 50 PD. We could not find MR in any of the three patients and noted severe adhesion between eyeball and Tenon's capsule. Ocular movement was severely limited horizontally and even vertically. RESULTS: Postoperatively Patient 1 showed orthophoria in follow-up of 2 years. Patient 2 had 16PD of exotropia in follow-up of 13 months, which was cosmetically acceptable. Patient 3 obtained orthophoria after surgery and developed 10 degrees of left head turning to avoid diplopia. CONCLUSIONS: When a patient shows longstanding large angle exotropia with limitation of adduction, we may consider the MR loss. A reasonable treatment may be to align the eyes cosmetically in primary position by weakening the abducting power and suturing the anterior part of nasal Tenon's capsule to the MR insertion site after adhesiolysis.

The Clinical Analysis of Surgical Methods in Intermittent Exotropia

PURPOSE: The outcome after operations for intermittent exotropia were frequently unsatisfactory because of high incidence of postoperative undercorrection, overcorrection or recurrence. The author studied surgical outcome of each operation method in intermittent exotropia. METHODS: The results of surgical treatment in 90 patients with intermittent exotropia were reviewed. The operative procedure were devided into 3 groups-bilateral rectus muscle recessions, unilateral lateral rectus muscle recession and medial rectus muscle resection and medial rectus muscle resection of dominant eye and lateral rectus muscle recession of non-dominant eye. The success of operation was defined as a final alignment of orthotropia, esotropia less than 5 prism diopter or exotropia less than 10 prism diopter in primary position at postoperative 6 months. RESULTS: The method of of operation in medial rectus muscle resection of dominant eye and lateral rectus muscle recession of non-dominant eye lead to higher success rate than other surgical method (96.7%) and the difference with statistically significant (p=0.03). The success rate of bilateral rectus muscle recessions group was 76.6%, and that of unilateral lateral rectus muscle recession and medial rectus muscle resection group was 80.0%. CONCLUSIONS: This result suggested that medial rectus muscle resection of dominant eye and lateral rectus muscle recession of non-dominant eye might be a most effective surgical method for intermittent exotropia.

A Case of Medial Rectus Muscle Injury after Functional Endoscopic Sinus Polypectomy and Ethmoidectomy

PURPOSE: To report appropriate treatment of medial rectus muscle injury after functional endoscopic sinus polypectomy and ethmoidectomy METHODS: The author experienced the right medial rectus muscle injury after functional endoscopic polypectomy and ethmoidectomy in a 42-year-old man who complained of decreased visual acuity, ocular pain, binocular diplopia, and exophthalmos in the right eye at the first postoperative day. His best corrected visual acuity of right eye was 0.3, Intraocular pressure was 26 mmHg, and pupillary light reflex was decreased. On exophthalmometry, the right eye was more exophthalmic by 3 mm than the left eye. After steroid therapy and befunolol eyedrops instillation, the visual acuity was improved to 0.8 and intraocular pressure was decreased to 18 mmHg. There was severe limitation of medial gaze and about 65 prism diopters of right exodeviation in red filter test. In computerized tomography, bony defect in the right orbital medial wall and defect in the right medial rectus muscle were confirmed. On the third postoperative day, silastic sheet was applied in dehiscent medial wall under endoscopic examination in otorhinolaryngologic outpatient department. Because exodeviation and diplopia had not improved, on the 61th postoperative day, right lateral rectus muscle recession 12 mm was carried out, and then, on the 88th postoperative day, Hummelsheim operation on right eye was done. RESULTS: Right exodeviation was decreased by about 40 prism diopters after right lateral rectus muscle recession 12 mm. and then, after Hummelsheim operation, he had right exodeviation 20 prism diopters of and less binocular diplopia. We prescribed 10 prism diopters of prism lens in each eye, but he complained of decreased visual acuity and cosmetic problem. So, we prescribed 5 prism diopters of prism lens in each eye. At the last follow-up he is satisfied with his visual acuity and cosmetic aspect.

The Surgical Results of Medial Rectus Muscle Resection of Dominant Eye and Lateral Rectus Muscle Recession of Non-dominant Eye in Intermittent Exotropia

Intermittent Exotropia has been treated by various surgical methods such as bilateral medial rectus resection, lateral rectus recession and medial rectus resection of deviating eye, and bilateral lateral rectus recession. However, the outcomes of such operations are unsatisfactory because of high incidence of postoperative undercorrection and overcorrection. Authors have performed a surgical method which is the medial rectus muscle resection of dominant eye and lateral rectus muscle recession of non-dominant eye in 68 patients. Authors considered the outcome successful if patients achieve deviation between 10 PD of exophoria and 5 PD of esophoria, good stereopsis, no suppression and no manifest deviation. The success rate was 83.8% (57/68) and there was no overcorrection over 6 months follow-up. As postoperative complications, 5 cases of temporary turning of face and 3 cases of asymmetric palpebral fissure were seen. Therefore, these results suggest that medial rectus resection of dominant eye and lateral rectus recession of non-dominant eye in intermittent exotropia may be an alternative surgical method for intermittent exotropia. However, further studies are necessary to determine the exact surgical amounts and mechanism of this surgical method.

Tracing Study on Neuroaxis of Medial Rectus Muscle in the Brain Stem of the White Rat

To clarify neuronal connection of the medial rectus muscle at brain stem, Bartha strain of the psecudorabies virus(PRV-Ba) and cholera toxin-horeserdish peroxidase(CT-HRP) was injected into medial rectus muscle of the rat. About 84 hours after PRV or CT-HRP injection, the brain was removed and processed immunohistochemical stain for PRV-Ba and neurohistochemical stain for CT-HRP using tetramethyl benzidine. The CT-HRP positive reaction was only present in ipsilateral oculomotor nucleus, contralateral abducence nucleus and bilaterally in rostral interstitial nucleus of medial longitudinal fasciculus, olivary pretectal nucleus, medial and superior vestibular nucleus, nucleus prepositus hypoglossi, prerubral field, nucleus Darkschewitsch, lateral substantia nigra, terminal nucleus of accessory nucleus, dorsal raphenucleus, locus ceruleus and pontime reticular formation. This study confirmed that both oculomotor nucleus and abducence nucleus were connected with each other through the medial longitudinal fasciculus, and neuronal connection of the medial rectus muscle in the rat brain stem.