Efficacy analysis of inferior oblique muscle belly transposition for small-angle asymmetric superior oblique palsy

Abstract

Asymmetric superior oblique palsy (SOP) is a complicated, non-comitant type of strabismus. Patients usually present with small-angle hypertropia in the affected eyes, accompanied by inferior oblique muscle overaction (IOOA). [1] Compensatory head posture and asymmetric development of the face are typically observed in congenital SOP, while diplopia is more common in an acquired SOP. [2] Prism glasses can improve diplopia and vertical deviation in the primary position, but they are not so successful at correcting non-comitant paralytic strabismus. In addition, vertical strabismus and compensatory head posture will return after the prism glasses are removed, wearing prism glasses will lower the vision of children prominently. Surgery like an inferior oblique muscle (IO) weakening procedure is often required eventually in those patients. However, conventional procedures for IO weakening may cause overcorrection and/or secondary A pattern in patients who have mild to moderate IOOA together with small-angle asymmetric SOP, posing a risk to its safety. [3] In the study by Caldeira, [4] 21% of the patients with mild to moderate IOOA developed A pattern following the surgery. Therefore, it remains a clinical challenge to select the most appropriate type of surgery for the treatment of small-angle asymmetric SOP. Inferior oblique muscle belly transposition (IOMBT), [5] a new IO weakening procedure introduced to our practice lately, has shown positive results in treating small-angle asymmetric SOP as well as a lower risk of complications such as overcorrection and secondary A pattern. In this study, we evaluated the efficacy and safety of the IOMBT procedure for the treatment of small-angle asymmetric SOP.

Effectiveness of modified inferior oblique muscle belly transposition for V-pattern exotropia combined with mild to moderate inferior oblique muscle overaction

“…It has been confirmed that the standard IOMBT was useful for the overaction of IO muscle [9][10] . We found IOOA in all cases were improved after the simplified procedure, and the cure rate was 87.0%, comparable to previously reported rates (71.0% [12] to 86.7% [13] ). Our study also demonstrated that the modified procedure also achieved a good effect on treating V-pattern exotropia.…”

“…The mean amount of V-pattern was reduced by 17.85±5.13 PD and the difference between the preoperative and postoperative value of V-pattern was significant (t=16.07, P<0.001). Analogously, Su et al [13] reported a mean reduction of 16.4±2.5 PD, and Si et al [14] described a similar reduction of 16.5±1.1 PD in V-pattern via the standard IOMBT surgery. Some features of the standard procedure got retained in the simplified procedure.…”

“…The emergence of new technology provides a useful addition to traditional methods and shows certain advantages in reducing risks of complications [9] . At present, a few studies have reported this technique [10][11][12][13][14] . Its indications become various gradually, such as IOOA [9][10][12][13][14] diplopia [11,13] or asymmetric superior oblique palsy [12][13] and so on.…”

“…At present, a few studies have reported this technique [10][11][12][13][14] . Its indications become various gradually, such as IOOA [9][10][12][13][14] diplopia [11,13] or asymmetric superior oblique palsy [12][13] and so on. We noticed that there were still not many reports about V-pattern strabismus [13][14] in related researches.…”

“…Its indications become various gradually, such as IOOA [9][10][12][13][14] diplopia [11,13] or asymmetric superior oblique palsy [12][13] and so on. We noticed that there were still not many reports about V-pattern strabismus [13][14] in related researches. Further to know about the new technique, we designed a retrospective study on the IOMBT procedure.…”