inferior oblique myectomy versus anterior and nasal transposition of its tendon for treatment of superior oblique muscle palsy

Conditions: Superior Oblique Palsy

Summary: this study aims at comparing the safety and efficacy of inferior oblique myectomy to anterior and nasal transposition of inferior oblique as two treatment options of superior oblique palsy regarding ocular alignment , alphabetical pattern correction , comitance and limitation of ocular motility

superior oblique palsy is one of the most common causes of vertical ocular muscle palsy. it may be congenital or acquired with over-elevation of the affected eye in primary position that increases in contralateral gaze and with ipsilateral head tilt . torsional and vertical diplopia may occur resulting in compensatory head tilt . bilateral superior oblique palsy is approximately 29%-38% of cases of superior oblique palsy. it is a rare congenital or acquired ocular motility disorder. it can be symmetrical or asymmetrical . superior oblique palsy can be treated by different types of surgeries including superior oblique strengthening by tucking of its tendon, contralateral inferior rectus muscle recession, recession of ipsilateral superior rectus muscle or inferior oblique weakening by disinsertion , myectomy , recession and anterior transposition . superior oblique tucking is an efficient and safe procedure for treatment of superior oblique palsy with vertical deviation less than 15 prism diopter in the primary position and remarkable superior oblique under action. the superior oblique forced duction test is the most important for planning surgery .this procedure may cause iatrogenic post-operative brown syndrome . recession of the ipsilateral superior rectus muscle reduces the upward force elevating the hypertropic eye. recession of the contralateral inferior rectus muscle is another option that reduces the force shifting the contralateral eye downward to match the position of the other hypertropic eye due to superior oblique muscle palsy . inferior oblique disinsertion is one of inferior oblique muscle weakening procedures with high efficacy when used simultaneously with superior rectus recession to control large vertical deviations in superior oblique palsy with contracture of superior rectus muscle . this may carry a high risk of postoperative overcorrection . inferior oblique recession is effective in weakening of its action and treatment of superior oblique palsy. inferior oblique myectomy is more effective than recession in improving hyper-elevation in primary gaze specially in those patients with small to moderate preoperative hyperopia . inferior oblique myectomy temporal to the inferior rectus muscle is the most popular procedure to treat inferior oblique over action and reduce vertical deviation . inferior oblique anterior transposition was first described at (1980) to correct both excyclotorsion and hypertropia in superior oblique palsy presenting with inferior oblique over action but this may be complicated by post-operative limited elevation . at 1992 -2001 antero-nasal transposition of inferior oblique was described to overcome these problems by converting inferior oblique muscle from an elevator and extorted muscle to depressor in adduction and intorted muscle . this makes it one of the surgical options for inferior oblique weakening in superior oblique palsy with reduction of antielevation complications associated with anterior inferior oblique transposition . the retrospective studies were done between 2012-2017 and for 6 months postoperative follow up that have reported postoperative inferior oblique over action rates of 1.7%- 5% following myectomy, 4% residual inferior oblique overaction was detected in recession in contrast to only 2% residual over action in the eyes that had inferior oblique anterior transposition with only 4% antielevation syndrome developed but with orthotropia in the primary position and no further surgery was performed .

Eligibility criteria:
inclusion criteria: * patients with superior oblique palsy (unilateral or bilateral) with no age restriction from males and females cases . exclusion criteria: - the following patients will be excluded: 1. patients with previous cyclo-vertical muscle surgeries. 2. connective tissue diseases. 3. previous orbital surgery.

Keywords: myectomy superior oblique palsy inferior oblique overaction anterior nasal transposition