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

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.

Modified inferior oblique anterior transposition for dissociated vertical deviation combined with superior oblique palsy: A case report.

BACKGROUND: Inferior oblique anterior transposition (IOAT) has emerged as an effective surgery in the management of dissociated vertical deviation (DVD) combined with superior oblique palsy (SOP). Traditional IOAT usually provides satisfactory primary position alignment and simultaneously restricts the superior floating phenomenon. However, it also increases the risk of the anti-elevation syndrome and narrowing of the palpebral fissure in straight-ahead gaze, especially after the unilateral operation. CASE SUMMARY: We report the outcomes of the modified unilateral IOAT in two patients with unilateral DVD combined with SOP. The anterior-nasal fibers of the inferior oblique muscle were attached at 9 mm posterior to the corneal limbus along the temporal board of the inferior rectus muscle, the other fibers were attached a further 5 mm temporal to the anterior-nasal fibers. Postoperatively, both hypertropia and floating were improved, and no obvious complications occurred. CONCLUSION: In these cases, the modified unilateral IOAT was an effective and safe surgical method for treating DVD with SOP.

Novel Inferior Oblique Muscle Y Splitting Procedure to Minimize the Anti-Elevation Syndrome: A Pilot Study.

Purpose: To describe novel Y splitting procedure of inferior oblique muscle to mitigate the anti-elevation syndrome. Methods: A pilot, prospective interventional study was undertaken to assess the effect of inferior oblique muscle Y-splitting in patients with unilateral 3+ or more overaction. To correct primary gaze hypertropia and the excyclotorsion, a Y-splitting procedure was performed (along with routine horizontal muscle surgery as per the deviation) in 14 subjects. The effect of surgery was assessed at baseline and at 6 months post-intervention. Results: The mean age of 14 subjects was 25.14±7.70 years. The mean pre-operative hypertropia, excyclotorsion and inferior oblique muscle over-action was 18.42±3.50 PD, 14.14±2.65 degrees, and +3.21±0.42 respectively. Following surgery, this was reduced to 1.57±1.74 PD of residual hypertropia (a net correction of 16.85±2.31 PD, p = 0.005), 3.85±1.46 degrees of residual excyclotorsion (a net correction of 10.28±1.72 degrees, p < 0.05), and +0.28±0.46 of residual inferior oblique over-action (a net correction ~+3) at the end of 6 months. Amongst fourteen patients, three patients still experienced residual/variable anti-elevation effect, and during the study period none of them experienced any adverse event and none of them required any additional surgeries. Conclusion: While anteriorizing the inferior oblique muscle to correct primary gaze hypertropia and the excyclotorsion, a novel "Y splitting" procedure can be followed to achieve the desired results with mitigated anti-elevation effect.