Insertion Of Inferior Rectus Muscle Research Articles

Anterior transposition of the inferior oblique and anti-elevation syndrome – how far to go?

ABSTRACT Purpose: To study the incidence of postoperative anti-elevation syndrome in relation to the magnitude of anterior transposition of the inferior oblique. Methods: A retrospective chart review was conducted for all patients submitted to anterior transposition of the inferior oblique from 2000 to 2020. Anti-elevation syndrome was defined as limitation of elevation of the abducting eye, resulting in a secondary upshoot of the contralateral adducting eye. Results: A total of 312 eyes of 170 patients were enrolled in the study. The incidence of anti-elevation syndrome was 20.4% when the inferior oblique was positioned 4 mm posterior to the temporal border of the inferior rectus insertion; 23.5% when sutured 2 mm posterior to the temporal border of the inferior rectus insertion and 32.8% when placed at the same level of the inferior rectus insertion with two sutures vertically aligned. When the posterior border of the inferior oblique was horizontally aligned with the anterior border and positioned adjacent to the inferior rectus insertion, in a “J shape” fashion, the incidence of anti-elevation was 41.8%. Conclusions: The anterior transposition of the inferior oblique with “J” deformity increases the risk of anti-elevation syndrome. Additionally, placing the sutures more anteriorly than 2 mm posterior to the inferior rectus insertion increases the incidence of this finding.

LARGE V PATTERN EXOTROPIA WITH BILATERAL INFERIOR OBLIQUE OVERACTION AND ITS CHALLENGING MANAGEMENT

Introduction : V pattern exotropia is a strabismus pattern with greater divergence in upgaze than downgaze. Various surgical treatment options were defined. This report demonstrates the management of largeV pattern exotropia with bilateral inferior oblique overaction (IOOA) by performing multiple surgeries.
 Case Illustration : A 20-year-old male came with a chief complaint of squinting eyes outward in both eyes since 9 years old. There was 90 PD exotropia in upgaze, 70 PD in primary gaze, 50 PD in downgaze. Bilateral IOOA grading was +3. Management in this patient was bilateral rectus lateral recession with partial hang back technique 11 mm and inferior oblique anteriorization of both eyes 1 mm posterior to inferior rectus muscle insertion. The IOOA on both eyes was eliminated post-operative, but there was 30 PD residual exotropia. The second step will be bilateral medial rectus resection.
 Discussion : A large V pattern with IOOA is challenging for management because it requires surgery of 2 muscles for each eye. The lateral rectus and inferior oblique muscles are close, so it was advantageous to operate simultaneously. Large exotropia requires surgery on many muscles, however operating on more than two muscles in one eye at a time can cause anterior segment ischemia. Therefore, bilateral medial rectus resection for residual exotropia will be done at different times.
 Conclusion : Large V pattern exotropia with inferior oblique overaction is a challenging case to manage. Due to its complex nature, it is advantageous to operate adjacent muscles.

Inferior oblique anterior transposition according to a different grading scale for hyperdeviation with inferior oblique overaction

ObjectifDéfinir une échelle de classement de la transposition antérieure de l'oblique inférieur (IOAT, pour inferior oblique anterior transposition) chez des patients présentant une hyperdéviation et une hyperaction de l'oblique inférieur (IOOA, pour inferior oblique overaction), selon des données issues de notre étude rétrospective antérieure. NatureÉtude de cohorte prospective. ParticipantsTrente-huit patients qui ont fait l'objet d'un classement de l'IOAT. MéthodesLes patients ont été répartis en 5 groupes en fonction de l'importance de l'hyperdéviation en position primaire (PPHD, pour primary position hyperdeviation). L'oblique inférieur a été transposé soit à 2 mm postérieur, à 1 mm postérieur, en parallèle, à 1 mm antérieur ou à 2 mm antérieur à l'insertion du droit inférieur, respectivement. La réussite de l'intervention chirurgicale se définissait comme suit : réussite complète (PPHD ≤ 3 dioptries prismatiques [DP]), réussite partielle (PPHD > 3 et ≤ 6 DP) et échec (PPHD > 6 DP). RésultatsLa correction moyenne de l'hyperdéviation par groupe après l'IOAT se chiffrait à 9,50 ± 0,9 DP (fourchette : 8–10 DP), à 12,43 ± 1,5 DP (fourchette : 11–14 DP), à 16,67 ± 1,4 DP (fourchette : 15–18 DP), à 19,57 ± 1,7 DP (fourchette : 16–21 DP) et à 22,57 ± 5,8 DP (fourchette : 14–30 DP), respectivement. L'intervention a été une réussite chez 34 patients (89,5 %), une réussite partielle chez 3 patients (7,9 %) et un échec chez 1 patient (2,6 %). Tous les patients de notre étude présentaient une IOOA unilatérale avant l'intervention; une IOOA est apparue dans l’œil controlatéral de 9 patients (23,7 %) pendant le suivi postopératoire. Une limitation de –2 du regard vers le haut est apparue chez 4 patients (57,1 %) du groupe 5, sans qu'il soit besoin de recourir à la chirurgie. ConclusionsIl est possible d'obtenir un taux élevé de réussite grâce à notre échelle de classement de l'IOAT en présence d'IOOA primaire et secondaire s'accompagnant d'une hyperdéviation en position primaire.

Vertical Strabismus - Indication of Surgical Techniques on the Inferior Rectus Muscle.

Surgery technique “cul-de-sac” is aprocedure with fixed adjustable sutures (non-absorbable suture), which are guided in parallel on both peaks original insertion of inferior rectus muscle. The node itself of suture is done in cutting the muscle and through the original insertion only leads arc suture. During „counterclockwise transposition“ procedure sec. Knapp, the horizontal rectus muscles are fixed at the straight inferior rectus muscle level. The author included their graphical diagrams. At the Department of Ophthalmology in the Faculty Hospital Královské Vinohrady in Prague (Czech Republic, EU) in the years 1996 - 2014 arelease relaxing operation of the inferior rectus musle by the technique “cul-de-sac” on 49 eyes. Indication was double elevator palsy in 31 patients, congenital fibrosis of the extraocular muscles in 15 patients and in 3 cases, it was thyroid eye disease. “Counterclockwise transposition” procedure sec. Knapp was indicated twice for paresis of the inferior rectus muscle in 2015 and 2016. For the first time, it was acongenital form. It was detected histologically atrophy of stripped muscle with hypertrophy collagen. The second traumatic form was formed after an orbital injury. We provided adequate relaxation of the inferior rectus muscle and practical restoration of eye elevation by the technique “cul-de-sac“ in 18 preschool children with the double elevator palsy and three adult patients with thyreiod eye disease. We had to restore motility to complete the procedure by classical transposition procedure sec. Knapp of both horizontal rectus muscles to the direct superior rectus muscle in elderly children and adults with the double elevator palsy, as well as in all patients with the congenital fibrosis of the extraocular muscles. Indicate the inclusion of this transposition influenced the degree of fibrotic rectus inferior muscle given by age. “Counterclockwise transposition“ procedure sec. Knapp ensured the practical disappearance hypertropie in both cases of paresis of the inferior rectus muscle. The alignment of the position of the eyes without diplopia in the direct view was ensured by prismatic correction. To release the fibrotically altered inferior rectus muscle in the double elevator palsy, the congenital fibrosis of the extraocular muscles and the thyroid eye disease, the operation of adjustable sutures was necessary in accordance with our experience with the technigue “cul-de-sac“ in its own modification. The transposition procedure sec. Knapp, either classical or “”counterclockwise” “ in its own modification, was of paramount importance for the solution of the vertical deviation of aparetic ethiology. Key words: adjustable sutures, congenital fibrosis of the extraocular muscles, double elevator palsy, thyroid eye disease, transposition procedure sec. Knapp, vertical strabismus.

Effect of inferior oblique anterior transposition in correcting vertical hyperdeviation in primary position

ObjectiveTo evaluate the effect of inferior oblique anterior transposition (IOAT) on improvement of vertical hyperdeviation in primary position. MethodsThis study was a retrospective review and included 35 eyes of 33 patients (18 males and 15 females). Patients with dissociated vertical deviation were not included in the study. Preoperative and postoperative average follow-up was 11.46 ± 11.73 and 11.43 ± 9.73 months, respectively. The eyes were divided into 5 groups according to the amount of transposition. Inferior oblique muscle was transpositioned 2 mm posterior to the inferior rectus insertion in group 1; 1 mm posterior to the inferior rectus insertion in group 2; parallel to the inferior rectus insertion in group 3; 1 mm anterior to the inferior rectus insertion in group 4; and 2 mm anterior to the inferior rectus insertion in group 5. ResultsThe mean preoperative and postoperative vertical hyperdeviation were 16.52 ± 5.54 and 0.97 ± 2.34 prism diopters (PD), respectively. The mean preoperative vertical hyperdeviation in group 1, group 2, group 3, group 4, and group 5 was 11.0 ± 4.24, 12.88 ± 4.26, 16.63 ±3.50, 19.83 ± 2.71, and 25.5 ± 3.00 PD, respectively. Postoperatively, improvement in vertical hyperdeviation in group 1, group 2, group 3, group 4, and group 5 was 11.0 ± 4.24, 11.63 ± 3.20, 15.46 ± 3.19, 18.17 ± 2.23, and 25.5 ± 3.00 PD, respectively. The vertical hyperdeviation had improved 100% in group 1; 90.2% in group 2; 92.9% in group 3; 91.59% in group 4; and 100% in group 5. ConclusionIOAT surgery planned according to hyperdeviation amount has effective and predictable results in correcting vertical hyperdeviation in primary position.

Surgical interventions for vertical strabismus in superior oblique palsy.

Superior oblique palsy is a common cause of vertical strabismus in adults and children. Patients may be symptomatic from binocular vertical diplopia or compensatory head tilt required to maintain single vision. Most patients who are symptomatic elect to undergo strabismus surgery, but the optimal surgical treatment for vertical strabismus in people with superior oblique palsy is unknown. To assess the relative effects of surgical treatments compared with another surgical intervention, non-surgical intervention, or observation for vertical strabismus in people with superior oblique palsy. We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) (2016, Issue 12), MEDLINE Ovid (1946 to 13 December 2016), Embase Ovid (1947 to 13 December 2016), Latin American and Caribbean Health Sciences Literature Database (LILACS) (1982 to 13 December 2016), the ISRCTN registry (www.isrctn.com/editAdvancedSearch); searched 13 December 2016, ClinicalTrials.gov (www.clinicaltrials.gov); searched 13 December 2016, and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en); searched 13 December 2016. We did not use any date or language restrictions in the electronic searches for trials. We included randomized trials that compared at least one type of surgical intervention to another surgical or non-surgical intervention or observation. Two review authors independently completed eligibility screening, data abstraction, 'Risk of bias' assessment, and grading of the evidence. We identified two randomized trials comparing four different surgical treatments for this condition, two methods in each trial. The studies included a total of 45 children and adults. The surgical treatments were all procedures to weaken the ipsilateral inferior oblique muscle. One study compared inferior oblique myectomy to recession of 10 mm; the other study compared inferior oblique disinsertion to anterior transposition (2 mm anterior to the temporal border of the inferior rectus insertion).We judged both studies to be at unclear risk of bias due to incomplete reporting of methods and other methodological deficiencies.Neither study reported data on the primary outcome of this review, which was the proportion of participants with postoperative surgical success, defined as hypertropia less than 3 prism diopters (PD) in primary gaze. However, both studies reported the average reduction in hypertropia in primary gaze. One study found that at 12 months' postoperatively the average decrease in hypertropia was higher in participants who underwent inferior oblique myectomy than in those who underwent recession, however data were not available for statistical comparison. The other trial found that after at least six months of follow-up, the mean decrease in primary position hypertropia was lower in participants who underwent inferior oblique disinsertion than in those who underwent anterior transposition (mean difference (MD) -5.20 PD, 95% confidence interval (CI) -7.76 to -2.64; moderate-quality evidence).Both trials also reported the average postoperative reduction in vertical deviation in adduction. One study reported that the average reduction in hypertropia in adduction was greater in participants who underwent inferior oblique myectomy than in those who underwent recession, but data were not available for statistical comparison. The other study found a lower decrease in hypertropia in contralateral gaze in participants who underwent inferior oblique disinsertion than in those who underwent anterior transposition (MD -7.10 PD, 95% CI -13.85 to -0.35; moderate-quality evidence).Secondary outcomes with sufficient data for analysis included proportion of participants with preoperative head tilt that resolved postoperatively and proportion of participants who underwent a second surgery. These outcomes were assessed in the trial comparing inferior oblique anterior transposition to disinsertion; both outcomes favored anterior transposition (risk ratio 7.00, 95% CI 0.40 to 121.39 for both outcomes; very low-quality evidence). None of the participants who underwent inferior oblique anterior transposition or disinsertion developed postoperative hypotropia or reversal of the vertical deviation. All participants who underwent inferior oblique anterior transposition developed elevation deficiency, which the authors deemed to be clinically insignificant in all cases, whereas no participants who underwent inferior oblique disinsertion experienced this complication. Additionally, the trial comparing inferior oblique myectomy to recession reported that no participant in either group required another strabismus surgery during the postoperative period. The two trials included in this review evaluated four inferior oblique weakening procedures for surgical treatment of superior oblique palsy. We found no trials comparing other types of surgical procedures for this disorder. Both studies had enrolled a small number of participants and provided low-quality evidence due to limitations in completeness and applicability. We therefore found no high-quality evidence to support recommendations for optimal surgical treatment of superior oblique palsy. Rigorously designed, conducted, and reported randomized trials are needed to identify the optimal surgical treatment for vertical strabismus in this disorder.

Treatment of large hypertropia following absence of inferior rectus by integrated anteriorization of inferior oblique combined with recession of superior rectus

To evaluate the effect of integrated anteriorization of inferior oblique muscle combined with recession of superior rectus to treat large hypertropia following absence of inferior rectus. It was a retrospective case series study. Integrated anteriorization of inferior oblique muscle means transposing inferior oblique muscle 8-10 mm posterior to the insertion directly to original insertion of inferior rectus without myotomy. We reviewed 5 patients with absence of inferior rectus muscle, who treated by integrated anteriorization of inferior oblique muscle combined with recession of superior rectus. The pre and post-operative vertical deviation in primary position, ocular motility, and abnormal head position were compared. The patients were followed up from 6 to 18 months, with average as 10.8 months. Postoperatively, 4 patients showed orthophoria in primary position and 1 patient had 10 PD hypotropia. The infraduction deficits improved from -3.0 to -1.6. Meanwhile, there had been an average of -2.0 mild supraduction limitation. Abnormal head position (AHP) disappeared in 2 patients with AHP before operation. All the patients showed no change of cyclodeviation on fundus photograph. 5 patients were satisfied with the improvement of the appearance, and the follow-up results were stable, no other surgery again. Integrated anteriorization of inferior oblique muscle combined with recession of superior rectus was an effective surgical selection to treat hypertropia with absence of inferior rectus muscle. This procedure doesn't need to cut off the inferior oblique muscle. The more convenient surgical procedure can reduce the risk of bleeding.

Modified Inferior Oblique Transposition Considering the Equator for Primary Inferior Oblique Overaction (IOOA) Associated with Dissociated Vertical Deviation (DVD)

Purpose: Inferior oblique anterior transposition (IOAT) should be done only in patients with inferior oblique overaction (IOOA) and dissociated vertical deviation (DVD) without fusional potential because the procedure can cause anti-elevation syndrome. This study reports the results of modified inferior oblique transposition onto the equator in 7 patients diagnosed with infantile exotropia or esotropia associated with IOOA and DVD.Methods: We performed modified inferior oblique (IO) transposition onto or considering the equator on 7 patients who had infantile exotropia or esotropia associated with IOOA and DVD. Five patients had infantile exotropia, and the other two patients had infantile esotropia. Six patients had undergone bilateral rectus -- Bilateral Lateral Rectus (BLR) or Bilateral Medial Rectus (BMR) -- recession previously and one patient underwent BLR recession and IO transposition simultaneously. They had more than +1.5 IOOA with DVD in both eyes. IO was transposed vertically onto the equator in this study. The mean distance between the lateral border of the inferior rectus insertion and the equator was 5.6 mm (range: 4.5 to 6.5 mm). Three months after the operation, degree of IOOA and DVD in each eye was evaluated.Results: IOOA and DVD were markedly reduced in all patients (+0.5 ∼+1 for IOOA postoperatively). Mild contralateral IOOA was noted but the motility disturbance was successfully corrected in all cases postoperatively.Conclusion: Bilateral IO transposition onto the equator could minimize antielevation and corrected IOOA and DVD successfully in patients with infantile exotropia or esotropia.

Combined resection and anterior transposition of the inferior oblique muscle for treatment of large primary position hypertropia caused by unilateral superior oblique muscle palsy

To evaluate the efficacy of combined resection and anterior transposition of the inferior oblique muscle for treatment of unilateral superior oblique muscle palsy with hypertropia from 20(Δ) to 25(Δ) in primary position. The medical records of consecutive patients operated on for unilateral superior oblique muscle palsy and hypertropia from 20(Δ) to 25(Δ) in primary position were retrospectively reviewed. All patients had overaction of the inferior oblique muscle. The inferior oblique muscle was disinserted and 4mm of its distal end was resected and transposed to the lateral border of the inferior rectus muscle insertion. The prism and alternate cover test was used to measure hypertropia. Surgical results were evaluated at 6months' follow-up. A total of 27 patients were included. The mean hypertropia in primary position was 22.6±0.4(Δ) preoperatively, which decreased to 1.4±0.6(Δ) after surgery. None of the patients developed hypotropia in primary position. Mild limitation of elevation was recorded in 1 patient, and 4 patients developed lower eyelid fullness. In this patient cohort, combined resection and anterior transposition of the inferior oblique muscle effectively treated unilateral superior oblique muscle palsy with hypertropia from 20(Δ) to 25(Δ) in primary position.

New strabismus surgical techniques

Five new strabismus surgical procedures were developed by the authors and were presented as a workshop at the AAPOS annual meeting of the American Association for Pediatric Ophthalmology and Strabismus. They are summarized here to introduce these methods to the reader and provide surgeons with more options in approaching difficult strabismus problems. Diagnosis and correction of consecutive strabismus attributable to stretched scar is discussed. The pulley posterior fixation procedure is a unique approach to correct high accommodative convergence or to augment a maximal medial rectus recession. Diagnosis and repair of the partial avulsion (flap tear) of a rectus muscle allows correction of some restrictive strabismus following blunt trauma. The nasal myectomy of the inferior oblique muscle corrects persistent inferior oblique overaction without sacrificing the tether effect gained by a previous anterior transposition of the inferior oblique. The full advancement of the superior oblique tendon offers another option to strengthen a weak superior oblique muscle.

Self-Grading Effect of Inferior Oblique Recession

Inferior oblique (IO) myectomy can result in self-adjustment; the greater the preoperative hyperdeviation, the larger the postoperative correction. This study estimated the effect of IO recession in primary position and in contralateral gaze. Records of 43 patients with IO muscle overaction associated with congenital unilateral superior oblique palsy were reviewed retrospectively. Seventeen patients who had a unilateral 10-mm recession (IO attached at 2 mm temporal and 3 mm posterior from the inferior rectus muscle insertion) and 26 patients who had a standard 14-mm recession were evaluated at 3 months postoperatively. The effect of the recession was measured by preoperative hyperdeviation minus postoperative hyperdeviation. The average preoperative hyperdeviation was 13.4 ± 4.83 prism diopters (PD) in primary position and 16.2 ± 6.32 PD in contralateral gaze in the 10-mm group and 8.0 ± 3.48 PD in primary position and 12.76 ± 4.55 PD in contralateral gaze in the 14-mm group. The average deviation at 3 months postoperatively was 2.1 ± 3.03 in primary position and 2.6 ± 3.95 PD in contralateral gaze in the 10-mm group and 0.8 ± 1.21 in primary position and 1.8 ± 1.95 PD in contralateral gaze in the 14-mm group. The range of self-adjusting effect at 3 months postoperatively was 3 to 20 PD in primary position and 5 to 30 PD in contralateral gaze in the 10-mm group and 3 to 15 PD in primary position and 4 to 24 PD in contralateral gaze in the 14-mm group. The self-grading effect was large and displayed no significant differences at 3 months postoperatively in the 10- and 14-mm groups (P = .104 and .560, respectively). Both IO recession procedures were largely self-grading and no significant differences were evident at 3 months postoperatively.

Anterior and nasal transposition of the inferior oblique muscle for dissociated vertical deviation associated with inferior oblique muscle overaction

To determine outcomes after anterior and nasal transposition of the inferior oblique muscle for dissociated vertical deviation (DVD) associated with inferior oblique overaction. A total of 10 patients who had bilateral DVD with ipsilateral inferior oblique muscle overaction were included in this study. Patients underwent anterior and nasal transposition of the inferior oblique muscles to the medial edge of the inferior rectus muscle insertion; the horizontal rectus muscle was operated on for horizontal strabismus in 2 cases. The primary outcome variables were changes in DVD, inferior oblique muscle action, V pattern, and vertical deviation in primary and side gazes. Patients were evaluated 6 to 10 months (mean, 7.3 months) postoperatively for alignment and oculomotor examination. Mean age at the time of surgery was 17.5 years. The average preoperative DVD for all eyes was 18.3(Delta) +/- 6.8(Delta), which decreased to 5.0(Delta) +/- 3.1(Delta) (p < 0.001) at 6 months. Mean inferior oblique muscle overaction decreased from +2.1 (range, +1 to +3) to +0.40 (range, -1 to 2). The mean preoperative V pattern was 24.9(Delta). After surgery, the mean correction of the V pattern was 14.8(Delta). Four patients developed 2(Delta) to 5(Delta) postoperative hypotropias in primary position at 6 months. Anterior and nasal transposition of the inferior oblique muscle reduces DVD, V pattern, and inferior oblique muscle overaction with minimal complications.

The Effect of Minimal Amount Inferior Oblique Recession in Superior Oblique Palsy

Purpose: To investigate the effect of vertical deviation change, head tilt and diplopia relief, we performed a minimal amount of inferior oblique recession regardless of the vertical deviation angle and the degree of inferior oblique overaction (IOOA) in superior oblique palsy patients. Methods: We retrospectively analyzed 20 cases of unilateral congenital or acquired superior oblique palsy, which were treated with inferior oblique muscle recession from May 2005, to August 2007. We compared vertical deviation change, head tilt and diplopia relief following surgery. Improvement of head tilt was determined by patient satisfaction measurements. The inferior oblique muscle was attached 4 mm posterior and 2 mm temporal to the lateral border of the inferior rectus muscle insertion in all patients. Results: The average angle of vertical deviation prior to surgery was 12.4 prism diopters (PD), and the total average correction in the angle of vertical deviation after surgery was 9.6PD. After surgery, head tilt improved in 13 of 16 eyes(81%), and of the four remaining eyes, vertical diplopia was absent. Conclusions: Although vertical deviation remained after surgery, if patients have enough vertical fusional amplitude, they should be able to overcome the diplopia and the head tilt. Judging from the indication of inferior oblique recession in diplopia and cosmetic problem in superior oblique palsy, a minimal amount of inferior oblique recession is thought to be an effective treatment of unilateral superioroblique palsy with no significant IOOA.

Case Report and Literature Review of Inferior Rectus Muscle Aplasia in 16 Japanese Patients

Purpose: To describe clinical features of inferior rectus muscle aplasia in Japanese patients and to gain insight into its pathogenesis. Methods: Case presentation and literature review of 16 Japanese patients with inferior rectus muscle aplasia. Results: The age at presentation of 16 patients (9 females, 4 males, and 3 with unknown gender) varied from 7 months to 73 years (mean, 21.8 years). The inferior rectus muscle was absent on the right side in 10 patients, on the left side in 4 patients, and on both sides in 2 patients. Structural anomalies of the eye globe, such as microphthalmos, microcornea, and coloboma of varying degrees, were present on the ipsilateral side of the inferior rectus muscle aplasia in 4 patients and on the contralateral side in 1 patient. As surgical findings, anomalous inferiorly located insertion of the medial rectus muscle was discovered in 5 patients: 1 patient in association with microcornea and iris coloboma. Frequent surgical procedures were recession or tenotomy of the superior rectus muscle, combined with downward transposition of the entire or partial tendons of the medial rectus and lateral rectus muscle to the medial and lateral end, respectively, of the putative inferior rectus muscle insertion. Conclusions: The association of coloboma with inferior rectus muscle aplasia suggests that abnormal optic fissure closure during embryogenesis might underlie the muscle aplasia.

The Inferior Oblique Muscle Adherence Syndrome

To describe the clinical features, etiology, prevention, and treatment of the inferior oblique muscle (IO) adherence syndrome. This series consists of 12 patients treated for a restrictive hypotropia in which the middle portion of the IO was scarred anteriorly, either into or near the inferior rectus muscle (IR) insertion, after prior surgery. Among the 12 patients treated, the mean hypotropia of the affected eye was 18.1 +/- 7.2 prism diopters and the mean excyclotropia was 13.8 degrees +/- 3.3 degrees . Causes of the IO adherence syndrome included IR surgery (with or without prior IO myectomy) and scleral buckling surgery. The syndrome responded well to surgically releasing or myectomizing the incarcerated IO, combined with ipsilateral IR recession. The IO adherence syndrome is a complication of surgery on the IR or of scleral buckling surgery, which can result in a restrictive hypotropia and excyclotropia. It can be prevented by paying attention to the anatomic relationship between the IO and IR and can be effectively treated if it occurs.

A 10-Year Overview of Double Elevator Muscle Weakening Procedures

To report the effect of weakening the superior rectus and inferior oblique (IO) muscles on ocular rotations. Observational case series. We reviewed a 10-year period of medical records of consecutive patients who underwent bilateral 5- to 11-mm (mean, 8.0 mm; SD, 1.1 mm) superior rectus muscle recessions combined with an IO muscle recession, myectomy, or anterior transposition. The effects on ocular rotations and eyelid position were recorded for the 37 patients (69 eyes) who were followed up for at least 6 months postoperatively. Nonparametric 1-way analysis of variance was used to compare results across the 3 procedures. The setting was a subspecialty practice at an academic institution. Supraduction deficiency was significantly associated with transposition of the IO muscle anterior to the inferior rectus muscle insertion compared with the standard IO muscle recession (P = .001), and IO muscle myectomy (P = .009). Y-pattern exotropia occurred more frequently after transposition of the IO muscle anterior to the inferior rectus muscle insertion than other weakening procedures (P<.001). Transposition of the IO muscle anterior to the inferior rectus muscle insertion, combined with ipsilateral superior rectus muscle recession, results in more supraduction deficiency and more frequent Y-pattern exotropia compared with standard IO muscle recession.

Anteriorization of inferior oblique muscle and downward transposition of medial rectus muscle for lost inferior rectus muscle

A 6-year-old boy who had been treated with bilateral medial rectus muscle recessions 3 years earlier for congenital esotropia was undergoing bilateral inferior oblique muscle recessions to correct inferior oblique muscle overaction. The right inferior rectus muscle was inadvertently cut during this surgery and was irretrievable. To manage this complication, the medial rectus muscle was transposed toward the inferior rectus insertion and the inferior oblique muscle was anteriorized. At the 1 year follow-up visit, no infraduction deficit was present on downgaze and only 8(delta) of left hypertropia was present in primary position.

Unilateral anterior transposition of the inferior oblique muscle for correction of hypertropia in primary position

Purpose To evaluate the correction of hypertropia in primary position with unilateral inferior oblique (IO) anterior transposition (IOAT). Methods Ten patients with idiopathic (nonparalytic, restrictive, or dissociated vertical deviation) hypertropia with marked IO overaction, who underwent unilateral IOAT, were prospectively evaluated to observe the correction of the hypertropia in primary position. No previous ocular muscle surgery had been performed. Four patients had esotropia and two had exotropia. In addition to the proposed surgery, horizontal procedures were performed to correct horizontal deviation, but no vertical transposition of horizontal muscles was done. Four patients had hypertropia and IO overaction, without horizontal strabismus, and IOAT was the only procedure performed. The IO muscle was reinserted 1 mm laterally to the lateral extremity of the inferior rectus muscle insertion using only one suture. The statistical analysis was performed by Wilcoxon rank sum test. Results The mean absolute correction in primary position was 18.1 prism diopters (PD) (range, 4 to 33), directly proportional to the size of the hypertropia before surgery. Nine of the 10 patients had a residual vertical deviation of ≤6 PD. After surgery, 4 patients (40%) presented limited elevation in adduction (−2) in the field of the operated IO, presumably caused by the antielevator effect of the transposed muscle, which did not improve during the follow-up period (range, 2 to 79 months). Conclusion Unilateral IOAT is an effective technique for correction of large hypertropia associated with marked unilateral IO overaction. Some lower lid curvature deformity and some limitation of elevation were observed in forced upgaze in some patients, but this was of no cosmetic importance.

Ocular kinematics, vergence, and orbital mechanics

Important aspects of ocular kinematics relate to the geometric configuration of extraocular muscles (EOMs). The orbital layer of each rectus EOM inserts on a connective tissue ring called a pulley that deflects the EOM path. Global layer fibers of each EOM pass through the pulley to insert on the sclera. The orbital layer thus controls linear translation of the pulley, regulating the EOM’s pulling direction, while the global layer rotates the eye. The active pulley hypothesis (APH) states that pulleys are actively positioned to regulate ocular kinematics. The coordinated control postulate of the APH proposes that during conjugate visually guided eye movements, rectus pulleys move the same anteroposterior distance as their insertions, but the inferior oblique pulley moves with vertical gaze by half the amount as the inferior rectus insertion. These motions, observable by magnetic resonance imaging (MRI), shift the pulling directions of these EOMs by half the ocular angle, mechanically implementing a ‘linear oculomotor plant’ appearing mathematically commutative to the brain and consistent with Listing’s Law of ocular torsion. In the non-converged state with the head upright and stationary, rectus pulleys move little transverse to the EOM axes. During convergence and during the static torsional vestibulo-ocular reflex, MRI shows that the rectus pulley array rotates around the line of sight. Oblique EOM orbital layers may implement this shift.

Anterior transposition of the inferior oblique muscle for treatment of superior oblique palsy.

Weakening of the inferior oblique muscle is the procedure of primary importance in patients with superior oblique palsy, Knapp's Classes I and III. In this study, the effectiveness of anterior transposition of the inferior oblique muscle in treatment of these patients was evaluated. Sixteen patients with superior oblique palsy, Knapp's Classes I and III, underwent anterior transposition of the inferior oblique muscle. The tip of the disinserted muscle was sutured to the sclera, parallel, and adjacent to the lateral border of the inferior rectus muscle insertion. The prism and alternate cover test measurements were made in all cardinal positions of gaze before and 6 months after surgery. The mean reduction of hyperdeviation was 15 prism diopters (PD) in the primary position, 23.4 PD in adduction, 26.65 PD in elevation and adduction, and 18.63 PD in depression and adduction. There was no hypotropia in the primary position. Mild limitation of upgaze has occurred in 3 of these patients, and mild fullness of the lower lid was developed by 25%. Postoperative hyperdeviation in the primary position was 5 PD or less in 15 out of 16 patients. The anterior transposition of the inferior oblique muscle is very effective in eliminating hyperdeviation in patients with superior oblique palsy, Knapp's Classes I and III. Up to 25 PD reduction of hyperdeviation in the primary position can be achieved. If this type of anterior transposition is used, primary position hypotropia or marked limitation of upgaze possibly will not occur.