Contralateral Inferior Oblique Overaction Research Articles

Effect of inferior oblique muscle belly transposition on versions and vertical alignment in primary position.

To evaluate the effect of inferior oblique muscle belly transposition (IOBT) on vertical deviation (VD) in primary position and inferior oblique overaction (IOOA). Twenty-eight patients who underwent unilateral IOBT for mild hypertropia (≤ 10△) due to unilateral IOOA were included. Surgical results regarding the correction of hypertropia, IOOA, and fovea disc angle (FDA) were analyzed and compared between groups A (VD ≤ 5△) and B (5△ < VD ≤ 10△). IOBT showed an overall reduction of 5.86△ (± 2.24△) of primary position VD, a mean correction of 1.00 (± 0.27) of IOOA, and an average change of 1.83° (± 3.02°) of FDA. The surgical success rate of IOBT for VD correction and IOOA elimination in all patients was 68% and 71%, respectively. The correction of VD was correlated with preoperative VD significantly (r = 0.86, p < 0.001). Consistently, IOBT demonstrated comparable efficacy in reduction of VD between group A and group B (p = 0.507). Furthermore, the two groups were comparable in the success rates for correcting VD and IOOA (both p > 0.05). None of the patients developed consecutive hypotropia, postoperative contralateral IOOA, or anti-elevation syndrome postoperatively. IOBT achieved satisfactory outcomes in patients with mild primary position VD (≤ 10△) that is associated with unilateral IOOA, without any risk of overcorrection of VD and contralateral IOOA for a follow-up period of up to 12months. This procedure is considered effective and safe alternative for weakening the IO in patients with appropriate surgical indications.

Retro-equatorial inferior oblique myopexy for treatment of inferior oblique overaction.

To compare the effectiveness of inferior oblique retroequatorial myopexy and inferior oblique myectomy in correction of inferior oblique overaction (IOOA). This was a pilot study study including forty patients with primary IOOA of all grades, with or without primary position horizontal deviations. Patients were randomized to have either IO retroequatorial myopexy, group A, or IO myectomy, group B. Success was defined as elimination of the IOOA at 6months postoperatively. Secondary outcome measures included residual or recurrent elevation in adduction, development of postoperative hypotropia in adduction, postoperative contralateral IOOA, major intraoperative complications, and reversibility of the procedure. At 6months postoperative, the success rate was higher in the myectomy group (76%) than in the myopexy group (58%); however, this difference was not statistically significant (P = 0.1). The incidence of residual IOOA in myopexy group was significantly higher in patients with higher preoperative grades of IOOA (P˂0.001). While this difference was not statistically significant among patients in myectomy group (P = 0.09). Collapse of V-pattern was acheived in nine (69%) patients in myopexy group compared with 8 (57%) in myectomy group with a statistically significant difference (P ≤ 0.001). No patients in myopexy group developed postoperative hypotropia in adduction or postoperative contralateral IOOA, compared with eight (22%) patients of myectomy group (P = 0.002) who developed postoperative hypotropia and two (66.6%) patients with unilateral IOOA who developed contralateral IOOA in myectomy group (P˂0.001). No intraoperative complications were encountered in either group. postoperative. Retroequatorial myopexy of the inferior oblique is as effective as inferior oblique myectomy in eliminating lower and moderate grades of primary IOOA; however, it is more effective in collapsing V-pattern associated with IOOA, and is not associated with postoperative hypotropia or contralateral IOOA after unilateral surgery. It can be used as a safe, reversible alternative to myectomy; however, it is not suitable for high grades of IOOA.

Masked bilateral superior oblique palsy in children.

Following surgery on an eye for unilateral superior oblique palsy, it is a well-recognized postoperative occurrence for the unoperated eye to develop superior oblique palsy, commonly referred to as masked bilateral superior oblique palsy. The purpose of this study was to describe this postoperative finding in children following unilateral inferior oblique weakening surgery. A retrospective review of records of children who underwent unilateral inferior oblique weakening surgery at Children's Hospital of Michigan, Detroit, Michigan, from 1987 to 2005, including information on the development of masked bilateral superior oblique palsy with contralateral inferior oblique overaction requiring a second surgical intervention. Of 50 children (25 boys and 25 girls, mean age: 5.6 years) who underwent unilateral inferior oblique weakening surgery (47 recessions and 3 myectomies), 9 (18%) manifested masked bilateral superior oblique palsy postoperatively, requiring subsequent surgical weakening of the inferior oblique muscle in the unoperated eye. Preoperative primary position hypertropia in children who were eventually diagnosed as having masked bilateral superior oblique palsy (5.56±4.22 prism diopters [PD]) was significantly smaller compared to children with unilateral superior oblique palsy (10.4±6.5 PD, P=.012), and preoperative primary position hypertropia of less than 5 PD was associated with an odds ratio of 8.2 (95% confidence interval: 1.7 to 38.5, P=.008) for requiring reoperation. Masked bilateral superior oblique palsy is a possible outcome after surgery for the correction of pediatric unilateral superior oblique palsy. Parents should be informed of this possible outcome, especially when primary position hypertropia is less than 5 PD.

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.

Contralateral Inferior Oblique Overaction after Inferior Oblique Recession in Unilateral Moderate Primary Inferior Oblique Overaction

Contralateral Inferior Oblique Overaction after Inferior Oblique Recession in Unilateral Moderate Primary Inferior Oblique Overaction

Inferior Oblique Transposition Onto the Equator: The Role of the Equator in Development of Contralateral Inferior Oblique Overaction

To investigate the role of the location of the equator and orientation of newly attached inferior oblique (IO) muscle in the development of contralateral inferior oblique overaction (IOOA). Fourteen patients (14 eyes) with 5 to 12 prism diopters (PD) of hyperdeviation in primary position with unilateral, congenital, superior oblique palsy were included. Seven patients underwent modified IO transposition onto the equator (equator group) and seven patients underwent modified IO 14-mm recession (14-mm group). IOOA in the contralateral eye and the angle of strabismus were assessed at 3 months postoperatively. Mean angles of hyperdeviation in primary gaze and sursoadduction were 0.7 and 2.1 PD in the equator group and 0.6 and 2.4 PD in the 14-mm group, respectively. Six patients (86%) developed anti-elevation syndrome and four patients (57%) showed definite 2+ or higher IOOA in the contralateral eye in the equator group. Three patients (43%) in the 14-mm group also developed contralateral IOOA, although it was 1+ or less. The postoperative difference in contra-lateral IOOA between groups was statistically significant (P = .04). This finding suggests that vertical orientation of the IO muscle is another important contributor in the development of contralateral IOOA in addition to the location of the newly attached IO muscle.

Mechanism of action of the inferior oblique following anterior transposition

Introduction: Following inferior oblique anterior transposition (IOAT), some believe contraction of the distal inferior oblique has an antielevation effect. IOAT is associated with persistent extorsion, especially in abduction. Extorsion can deflect the paths of the rectus muscles and cause relative contralateral inferior oblique overaction (IOOA). To understand this effect, the action of the inferior oblique muscle following three surgical procedures (IOAT, recession, and myectomy) was studied.

Magnetic resonance imaging of an unusual case of Brown's syndrome with contralateral superior oblique palsy

Brown’s syndrome as a rule occurs as an isolated anomaly, 1 although various ocular and systemic associations have been reported. 2 The simultaneous occurrence of Brown’s syndrome in 1 eye and a superior oblique palsy in the other eye is a very rare association. 3 We report an unusual case of congenital atypical Brown’s syndrome documenting a hitherto unseen defect in the contralateral superior oblique muscle by using high-resolution magnetic resonance imaging (MRI). Coronal high-resolution MRI showed a significantly decreased cross-sectional area of the left superior oblique and a lack of its contractile change with vertical gaze confirming the presence of superior oblique palsy in the contralateral eye. 4 The purpose of this case report is to document bilateral superior oblique anomalies, atypical Brown’s syndrome in 1 eye, and contralateral inferior oblique overaction caused by a superior oblique palsy in the other eye.