Overelevation In Adduction Research Articles

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.

Outcome of Strabismus Surgery for Exotropia in a 4-year-old with Silver-Russell Syndrome (SRS): A Case Report

Silver-Russell Syndrome (SRS) is a rare disorder associated with prenatal and postnatal growth retardation with associated characteristic facial and ocular features including strabismus. We report the outcome of strabismus surgery performed for exotropia in a 4-year-old patient with SRS. The patient presented with decreased visual acuity and constant exotropia of the right eye noted since 3 months of age. Systemic SRS characteristics consisted of relative macrocephaly, short stature, forehead prominence and stunted growth pattern. An X-pattern exotropia is consistent with bilateral tight lateral recti muscles with over-elevation in adduction of the left eye was present. Patient underwent unilateral right lateral rectus recession and right medial rectus resection for a 50-prism diopter constant exotropia. Patient had a favorable outcome of within 8 prism diopters from orthotropia at 1st, 3rd-, 6th- and 12th-month post-operatively.

The Role of Hypertropia in the Surgical Management of Bilateral Inferior Oblique Muscle Overaction

ABSTRACT Purpose Inferior oblique muscle overaction (IOOA) is an ocular motility anomaly consisting of overelevation in adduction, often associated with ipsilateral hypertropia. The weakening procedure of IO muscle is the most widely used procedure in IOOA. Usually, surgical planning is based on the degree of overaction of the IO muscle. Materials and Methods We have retrospectively analyzed patients with bilateral IOOA with and without hypertropia in primary position, who underwent a bilateral IO weakening procedure. Both the amount of IOOA and the presence of a hypertropia in primary position were taken into consideration for the surgical plan. Results Nineteen patients met the entry criteria for this study. In 12 patients, a hypertropia in primary position was present at baseline, and it was significantly lower after the asymmetrical IO weakening: 11 had an asymmetric IOOA at baseline, and one had symmetric IOOA. None of the remaining seven patients had a vertical deviation in primary position before surgery, despite having asymmetric IOOA. None of them developed a hypertropia in primary position after symmetric IO weakening. Conclusions Our findings outline the utility of considering both the presence of a vertical deviation in primary position and the magnitude of IOOA in this set of patients. Asymmetric inferior oblique weakening procedure is effective in treating a hypertropia in the primary position and bilateral IOOA.

Special features of superior oblique hypofunction due to tendon abnormalities

ABSTRACT While most cases of superior oblique (SO) hypofunction represent contractile weakness due to denervation, sometimes the lesion is exclusively in the tendon. This study sought to distinguish the pattern of incomitant strabismus caused by deficiency of SO oculorotary force caused by tendon abnormalities versus that of neurogenic palsy. Clinical and magnetic resonance imaging (MRI) findings of 7 cases of unilateral SO tendon interruption or extirpation were compared with 11 cases of age matched unilateral SO palsy having intact tendons. We compared angles of misalignment with high-resolution MRI in central gaze and deorsumversion. Muscle bellies in neurogenic palsy were markedly atrophic with maximal cross sections averaging 6.5 ± 2.7 mm2, in contrast with 13.5 ± 3.0 mm2 contralesionally (P < .0001). In contrast, SO muscle bellies ipsilateral to tendon interruption had maximum cross sections averaging 15.1 ± 3.0 mm2 occurring more posterior than on the contralesional side whose maximum averaged 12.1 ± 2.4 mm2. While cross sections of SO bellies ipsilateral to tendon interruption exhibited normal contractile increase in infraduction (P < .0005), there was nevertheless strabismus with incomitance similar to that in SO atrophy. Binocular alignment was statistically similar (P > .5) in the two groups for all diagnostic positions, including head tilt, except in deorsumversion, where cases with SO tendon abnormalities averaged 20.5 ± 6.9Δ ipsilateral hypertropia, significantly more than 8.5 ± 6.6Δ in neurogenic SO atrophy (P = .001). The average difference in hypertropia Hypertropia averaged 9D greater in deorsumversion than central gaze in tendon abnormalities, but 4.1Δ less in SO atrophy (P< .019). In contralesional version, average overelevation in adduction was 1.7 (scale of 0–4) in tendon abnormalities, and 2.6 in SO atrophy (P = .23), while average underdepression in adduction was −2.3 in cases of tendon abnormalities and −1.6 in SO atrophy (P = .82). Repair of the SO tendon in three cases was effective, while alternative procedures were performed when repair was infeasible. While both denervation and tendon interruption impair SO oculorotary function, interruption causes greater hypertropia in infraversion. Surgical tightening of interrupted SO tendons may have particularly gratifying effects. Posterior SO thickening and large hypertropia in infraversion suggest SO tendon interruption that may guide a surgical strategy of tendon repair.

Congenital ocular counter-roll: a review of cases treated exclusively by ophthalmologists.

To review the demographics, clinical manifestations, and surgical experiences of patients with congenital ocular counter-roll, whose treatments were performed exclusively by ophthalmologists. A retrospective review was conducted consisting of patients who received strabismus surgery between 2017 to 2019. Patients with obvious ocular counter-roll were included. A total of 7008 patients who received strabismus surgery, 28 (12 males, 16 females) were diagnosed as congenital ocular counter-roll, accounting for 0.40%. All patients were initially misdiagnosed: 21 patients were misdiagnosed as superior oblique palsy (SOP), 3 as inferior oblique overaction, 2 as dissociated vertical deviation (DVD), 1 as superior oblique overaction with A-pattern exotropia, and 1 as medial rectus palsy. The mean±SD age was 12.4±9.4y (range 2.5-36y). The most common clinical findings included ocular counter-roll, vertical deviation or vertical deviation combined with outward deviation and head tilt. At follow-up, an excellent surgical result was achieved in 20 patients. Preoperative horizontal deviation of 26±24 prism diopter (PD) and vertical deviation of 18±12 PD were reduced to 0±12 PD (P=0.0001) and 3±4 PD (P=0.001), respectively. Congenital ocular counter-roll is a rare supranuclear vertical strabismus caused by congenital abnormalities involving vestibule-ocular reflex pathways. In addition to ocular counter-roll, the most salient clinical features included, but are not limited to, hyperdeviation, outward deviation, overelevation in adduction and head tilt.

Range of forced cyclorotation in superior oblique palsy and V-pattern strabismus.

To quantify a passive range of cyclorotation using a smartphone application and evaluate its associations with fundus torsion and rectus muscle cyclorotation in superior oblique palsy (SOP) and V-pattern strabismus. Fifty-two patients showing overelevation in adduction (30 with congenital SOP and 22 with V-pattern strabismus) underwent forced cyclorotation on the photographs. A photograph of the globe was taken in maximally excyclorotated and incyclorotated positions after marking at the 6 and 12 o'clock limbus under general anaesthesia, and the rotational alignment of these markings was read using the toriCAM application. The degrees of forced cyclorotation were compared between the two groups. Disc-fovea angle on fundus photographs and rectus muscle cyclorotation in the coronal view on orbital computed tomography were correlated with the range of forced excyclorotation. The range of forced excyclorotation was greater in V-pattern strabismus than that in SOP (58.5° vs. 46.8°, p < 0.001), whereas the ranges of incyclorotation were similar between the two groups (39.0° vs. 39.0°, p = 0.543). Regression analysis revealed a significant increase in the range of excyclorotation with the degree of rectus muscle excyclorotation, after accounting for age and angle of hypertropia (r2 = 0.475, p = 0.001). The range of excyclorotation did not correlate with the amount of fundus extorsion and grade of overelevation in adduction. The range of excyclorotation was correlated with the rectus muscle excyclorotation in these populations, suggesting that the results from this forced cyclorotation test may reflect orbital alignment and oblique muscle status.

Morphological Differences in the Inferior Oblique Muscles from Subjects with Over-elevation in Adduction.

PurposeWe examined inferior oblique muscles from subjects with over-elevation in adduction for characteristics that might shed light on the potential mechanisms for their abnormal eye position.MethodsThe inferior oblique muscles were obtained at the time of surgery in subjects diagnosed with either primary inferior oblique overaction or Apert syndrome. The muscles were frozen and processed for morphometric analysis of myofiber size, central nucleation, myosin heavy chain (MyHC) isoform expression, nerve density, and numbers of neuromuscular junctions per muscle section.ResultsThe inferior oblique muscles from subjects with Apert Syndrome were smaller, and had a much more heterogeneous profile relative to myofiber cross-sectional area compared to controls. Increased central nucleation in the Apert syndrome muscles suggested on-going myofiber regeneration or reinnervation over time. Complex changes were seen in the MyHC isoform patterns that would predict slower and more sustained contractions than in the control muscles. Nerve fiber densities were significantly increased compared to controls for the muscles with primary inferior oblique overaction and Apert syndrome that had no prior surgery. The muscles from Apert syndrome subjects as well as those with primary inferior oblique overaction with no prior surgery had significantly elevated numbers of neuromuscular junctions relative to the whole muscle area.ConclusionsThe muscles from both sets of subjects were significantly different from control muscles in a number of properties examined. These data support the view that despite similar manifestations of eye misalignment, the potential mechanism behind the strabismus in these subjects is significantly different.

Clinical Manifestations, Diagnosis, and Surgery of Inferior Oblique Muscle Ectopia.

Objectives To summarize the clinical manifestations, diagnosis, treatment, and prognosis for inferior oblique muscle ectopia (IO-E). Subjects and Methods. Patients diagnosed with IO-E during strabismus surgery from March 2017 to September 2018 were included in this retrospective, cross-sectional study. All patients received preoperative Krimsky test, synoptophore, cycloplegia refraction, fundus torsion, and other strabismus-related specific tests. The anatomic variations of IO-E were always discovered during surgical procedure. Postoperative eye position and binocular visual function (BVF) were all reviewed in early days after operation. Results A total of 7 patients were enrolled in this study with an average age of 6.4 ± 3.8 yrs. They all presented with significant exotropia and unilateral (or bilateral) overelevation in adduction (OEA). No compensatory head position was detected. Some of them had vertical deviation, V pattern, or excyclotropia, which were indicated by fundus torsion. Monocular or binocular IO-E was distinguished during the surgery, and it could be classified into two types according to its anatomic features. In surgery, the ectopic IO muscle bundle was restored, and different IO weakening methods were employed. Meanwhile, the horizontal deviation was also corrected according to the preoperative examination. Eyes of all patients were properly aligned in the primary position after surgery. Varying degrees of BVF appeared in 3 cases. Conclusions IO-E is a rare congenital dysplasia variation of the extraocular muscle, which could appear as inferior oblique overaction. It is difficult to diagnose before surgery, and weakening the overactive ectopic inferior oblique was required for better prognosis if this condition was confirmed during surgery.

Comparison of unilateral recession or resection of the inferior oblique muscle during anterior transposition for treatment of asymmetric vertical strabismus

Dissociated vertical deviation (DVD) and overelevation in adduction (OEAd) occur frequently in children with infantile strabismus. This study evaluated the efficacy of combining bilateral inferior oblique muscle anterior transposition (IOAT) with unilateral recession or resection of the muscle for patients with asymmetric DVD and OEAd.

Lateral rectus sag and recurrent esotropia in children

To describe the clinical and intraoperative findings of an anatomic abnormality in children that resembles sagging eye syndrome documented in older adults and that led to recurrent esotropia after surgery. We reviewed records of 4 patients with substantial recurrent esotropia after bilateral medial rectus recession who required subsequent surgery combining lateral rectus resection with correction of the anatomic abnormality affecting the lateral rectus path. Binocular alignment was sequentially analyzed. Three young patients (2-3years of age) presented with acquired esotropia but minimal cycloplegic refractive error. The fourth patient (14years of age) initially had moderate hyperopia and partially accommodative esotropia, but subsequently developed marked bilateral overelevation in adduction. In all patients, esotropia recurred within 5Δ of preoperative deviation after bilateral medial rectus recession. Surgical exposure demonstrated that bilateral lateral rectus paths were inferiorly displaced more than one-half tendon width from their normal paths near the globe's equator, despite normal scleral insertions. Equatorial myopexy and lateral rectus resection resulted in stable esotropia correction. Lateral rectus sag in children creates a type of acquired esotropia and overelevation in adduction poorly responsive to standard surgery but correctable with lateral rectus resection and equatorial myopexy that normalizes the lateral rectus path through permanent scleral fixation.

Spontaneous Regression of Over-elevation in Adduction Following Esotropia Surgery.

To evaluate the course of over-elevation in adduction in patients who had esotropia following correction of horizontal deviation. The review of the medical files identified 28 patients who had esotropia with over-elevation in adduction. Data collected from the patients' full ophthalmological examinations included visual acuity, ocular alignment, duction, versions and sensory tests for binocularity and stereopsis, cycloplegic retinoscopy, and fundus evaluation. Oblique muscle function was graded on a scale of -4 to +4. The primary outcome measure was the amount of improvement in over-elevation in adduction following esotropia surgery. Of the 28 patients (mean age: 53.5 ± 53.7 months), 13 were males and 15 were females. Of these, 22 (78.6%) had infantile esotropia and 6 (21.4%) had partial accommodative esotropia. The mean follow-up was 16.3 ± 7.9 months. All patients underwent bilateral medial rectus recession for correction of esotropia. The mean preoperative inferior oblique overaction was +2.1 ± 0.7 and the final postoperative value was +0.8 ± 0.9 (P < .001). There was a statistically significant decrease in postoperative over-elevation in adduction at all postoperative visits compared to the preoperative value (P < .001 at 3- and 6-month and final visits). Over-elevation in adduction regressed in 42 eyes (80.8%). Of these, 18 eyes (34.6%) completely resolved without any additional surgery to the inferior oblique muscle. Spontaneous regression in over-elevation in adduction was observed after esotropia surgery without additional inferior oblique weakening surgery. This may affect presurgical evaluation of and surgical planning for patients.

Intermittent exotropia course in frontonasal dysplasia and severe orbital hypertelorism: Case report

Frontonasal dysplasia is a rare condition of congenital structure malformations of the midface. Ophthalmologic abnormalities have been estimated to occur in 87% of cases of frontonasal dysplasia. We report a case of type I frontonsal dysplasia in a 15-year old boy after the correction of severe hypertelorism, median nasal cleft w~ith a broad nasal root and associated decompensated intermittent exotropia with overaction. of the inferior oblique muscles and V pattern. He underwent bilateral lateral rectus recessions of 6.0 mm for intermittent exotropia when he was six years old. The correction of hypertelorism was performed with orbital rotation surgery when he was thirteen years old. For some time after strabismus surgery, the ocular alignment improved, but it deteriorated gradually. The ocular alignment improved after the hipertelorismus correction; however, intermittent exotropia deteriorated gradually again six to seven months later. On the last ophthalmologic examination, he had the ocular alignment on the level of small angle exotropia and associated hypertropia and occasionally even.small angle esotropiaat near. There was bilateral overelevation in addiction and V pattern, which remained unchanged after extensive facial bones surgical procedures. The high incidence of ocular abnormalities, particularly exodeviations, indicates that the early assessment by an ophthalmologist should be a part of the initial evaluation of patients with frontonasal dysplasia to detect treatable visual or ocular problems.

Accessory fibrotic lateral rectus muscles in exotropic Duane syndrome with severe retraction and upshoot

FIGURE 1. Final position of lateral rectus (LR) and accessory bands. A 3.5-year-old boy presented at the University of California Los Angeles–Olive View Hospital with abnormal eye movements present since birth. His parents noticed that his left eye always appeared smaller than his right eye and that he had a right head turn. On examination, the patient demonstrated a 5 right head turn. In forced primary position, he had an exotropia of 6. He had 2 limitation to adduction and abduction and13 overelevation in adduction (upshoot) in the left eye. The decision was made to perform surgery consisting of a lateral rectus recession with Y-splitting for presumed exotropic Duane syndrome with a significant upshoot. Preoperative forced duction testing revealed moderate restriction to adduction and no restriction to abduction. The surgical video demonstrates the presence of 2 accessory bands posterior to the lateral rectus muscle. All 3 structures (the lateral rectus and the 2 accessory bands) were recessed to 17 mm from the limbus in a V-shaped configuration (Figures 1 and 2). At postoperative month 1, the patient was orthotropic in primary position, and his upshoot had resolved. His adduction improved to 1 but his abduction worsened to 3. First reported in 1893 by Nussbaum, accessory muscles have been well described in disorders such as Duane syndrome and congenital fibrosis of the extraocular muscles. They should be suspected in patients with atypical patterns of restrictive strabismus, globe retraction in directions other than adduction, or in patients with severe upor downshoots. Lueder described 3 types of accessory bands in his 2002 review: (1) structures arising from extraocular muscles and inserting in abnormal locations, (2) fibrous

Accommodative esotropia decompensated to cyclic esotropia in a 6-year-old boy

Cyclic esotropia, characterized by alternating intervals of esotropia and orthotropia, is associated with decreased vision, trauma, strabismus surgery, or central nervous system disease. We report a 6-year-old boy who developed cyclic esotropia after 3 years of successful control of accommodative esotropia with full hyperopic correction. After bilateral medial rectus recession, he remained esophoric with good binocular function and stereoacuity. To our knowledge, this is the first report of accommodative esotropia decompensating into a cyclic esotropia.

Crouzon Syndrome: Relationship of Rectus Muscle Pulley Location to Pattern Strabismus

Investigate the relationship between the extorsion of the rectus muscle pulleys and the V-pattern exotropia and "overelevation in adduction" observed in Crouzon syndrome. Twenty children with Crouzon syndrome had assessment of eye alignment. The horizontal and vertical positions of the four rectus muscle pulleys were estimated from coronal CT images. Eye alignment was simulated in Orbit 1.8 software by shifting the corresponding location of the rectus muscle pulley array. Eleven of the 20 patients had a V-pattern exotropia with displacements of each rectus muscle pulley ranging from 2 to 7 mm. The remaining nine patients were orthotropic with <2 mm displacement of the rectus muscle pulleys. Simulated displacements (>2 mm) of either the horizontal or vertical rectus muscle pulleys produced a similar strabismus pattern. The amount of V-pattern exotropia observed clinically was highly correlated with the amount predicted by pulley displacements in Orbit 1.8 (r(2) = 0.63; P < 0.0001). The displacement of vertical and horizontal rectus muscle pairs was significantly higher for patients having overelevation in adduction. Rotation of the four rectus muscle pulleys relative to the corresponding rotation planes of the globe changes the direction and magnitude of their active and passive pulling forces in a gaze-dependent manner. Extorsion of the horizontal and vertical rectus muscle pulleys in Orbit 1.8 reproduces the pattern strabismus observed in Crouzon syndrome. The high correlation between the predicted magnitude of the V-pattern exotropia and observed exotropia indicates that extorsion of the rectus muscle pulleys primarily accounts for the pattern strabismus.

Improving ophthalmic outcomes in children with unilateral coronal synostosis by treatment with endoscopic strip craniectomy and helmet therapy rather than fronto-orbital advancement

To compare long-term ophthalmic outcomes in infants treated for unilateral coronal synostosis (UCS) by endoscopic strip craniectomy (ESC) and helmet therapy with those treated by fronto-orbital advancement (FOA). Consecutive patients with UCS, uncomplicated by other suture synostosis, were identified by a retrospective review of medical records. Assessment of presence of amblyopia, cycloplegic refraction, strabismus, and strabismus surgical intervention at all visits was recorded. Between 2004 and 2010, 22 patients were treated by FOA (mean follow-up, 21.5 months) and 21 patients with ESC and helmet therapy (mean follow-up, 23.5 months). The mean aniso-astigmatism was equal; however, the SD was greater for those treated by FOA (P < 0.05). A more severe pattern of strabismus developed in those treated by FOA (P < 0.0001). Those treated by FOA were more likely to have amblyopia (P = 0.0015) and to undergo surgical correction of their strabismus (odds ratio, 6.3:1). Children with UCS treated with ESC and helmeting had less severe overelevation in adduction, amblyopia, extremes of astigmatism, and less need for strabismus surgery than those treated by FOA. Although the reason for these more favorable outcomes remains uncertain, we speculate that the earlier timing of ESC or differences in the anatomical changes resulting from the two procedures may play a role.

Congenital Superior Oblique Palsy and Trochlear Nerve Absence: A Clinical and Radiological Study

To evaluate patients with congenital superior oblique palsy (SOP) by classifying them according to their magnetic resonance imaging (MRI) findings and cross-comparing the clinical characteristics of each group. Retrospective, observational study. Ninety-seven consecutive patients diagnosed with congenital SOP. Medical records of patients who demonstrated typical signs of congenital SOP were reviewed. The presence or absence of the trochlear nerve was visualized with thin-section high-resolution MRI of the cranial nerves. Presence of the trochlear nerve and superior oblique (SO) muscle hypoplasia on MRI, age at the onset of symptoms or signs, ocular motility examination results, objective ocular torsion, and surgical outcomes. Of the 97 patients with congenital SOP, 73% of patients were identified with an ipsilateral absent trochlear nerve and variable degree of SO muscle hypoplasia (absent group), whereas the remaining 27% had a normal trochlear nerve and normal symmetric SO muscle (present group). Patients with an absent trochlear nerve showed more frequent head tilt (P = 0.030) that was manifest at an earlier onset before 1 year of age (P<0.001). Patients with a normal trochlear nerve had a more prominent overelevation in adduction (P = 0.008) and more frequently were associated with dissociated vertical deviation (DVD; P = 0.025). Congenital SOP patients without a trochlear nerve had a hypoplastic SO muscle and frequently manifested head tilt at an earlier age, whereas patients with a normal trochlear nerve showed prominent overelevation in adduction and frequent DVD. The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Effect of Ocular Torsion on A and V Patterns and Apparent Oblique Muscle Overaction

To determine if ocular torsion is a major cause of A and V patterns and oblique muscle overaction or merely a contributing factor. Three separate investigations were conducted. (1) The trajectory of eyes with oblique muscle overaction was plotted across the horizontal field of gaze from videographs to determine if it was linear or curvilinear. (2) The effect of successful Harada-Ito surgery to reduce extorsion on overelevation in adduction in patients with fourth cranial nerve palsy was studied. (3) The effect of successful surgery to treat pattern strabismus in the form of vertical transposition of the horizontal rectus muscles on objective torsion was studied. (1) Three eyes with inferior oblique muscle overaction and 2 with superior oblique muscle overaction had a curvilinear rise or fall (respectively) as they moved into adduction. (2) Surgery that successfully decreased extorsion had a negligible effect on overelevation in adduction in 2 patients. (3) Horizontal rectus muscle transposition that was uniformly successful in eliminating A or V patterns consistently caused an increase in objective torsion in all 5 patients studied. Ocular torsion may contribute to A or V patterns and overelevation or overdepression in adduction, but it is probably not the major cause of these phenomena.

MR imaging of familial superior oblique hypoplasia

BackgroundCongenital superior oblique palsy is usually associated with a structural abnormality of the superior oblique tendon. There have been many reports of familial congenital superior oblique palsy. However, there has...

Anterior and nasal transposition of the inferior oblique muscles in patients with missing superior oblique tendons

Patients with missing superior oblique (SO) tendons present with overelevation/underdepression in adduction. Unilateral cases often exhibit abnormal head postures, whereas in bilateral cases, there may be a marked V-pattern with upgaze exotropia. These patients may have craniosynostosis. Nine children with unilateral (n = 2) or bilateral (n = 7) absent SO tendons underwent anterior and nasal transposition of the inferior oblique (IO) muscles, some in combination with horizontal rectus recession for horizontal strabismus. They were evaluated 6 to 46 months postoperatively for alignment and oculomotor examination. Cyclodeviations were not evaluated in most children. Postoperatively, all patients improved. Both unilateral cases were orthotropic with no abnormal head posture. In the bilateral cases, vertical deviation in adduction and exotropia in upgaze had largely cleared, although some symptoms remained, most notably vertical deviation in side gaze (3 patients) and V-pattern esotropia in downgaze (2 patients). A patient missing both SO tendons as well as the left superior rectus muscle, who had the anterior and nasal transposition on the right side only, remained with 25(Delta) left hypotropia. Anterior and nasal transposition of the IO muscle reduces overelevation in adduction and helps eliminate or reduce divergence of the eyes in upgaze, but esodeviation may persist in downgaze. This procedure was most effective in unilateral absence of the SO tendon. It is likely to benefit patients with severe congenital fourth nerve palsy in which standard IO muscle weakening procedures have been ineffective.