Inferior Oblique Belly Transposition for Small Angle Hypertropia With Inferior Oblique Overaction: A Pilot Study.

PURPOSE: To evaluate the efficacy of transposition of the belly of the inferior oblique muscle in treating inferior oblique overaction with small angle hypertropia.

METHODS: The medical records of 10 patients who underwent inferior oblique belly transposition from March 2014 to July 2016 were reviewed. Transposition of the inferior oblique muscle belly consisted of suturing the entire body of the muscle to the sclera 5 mm posterior to the temporal insertion of the inferior rectus muscle. All patients had small hypertropias (< 5 prism diopters) in the primary gaze position with associated inferior oblique overaction. Deviations in both primary and lateral gazes, compensatory face turns or head tilts, and the degree of inferior oblique overaction were evaluated preoperatively and postoperatively.

RESULTS: Nine of the 10 patients had a complete resolution of inferior oblique overaction. In the remaining patient, the inferior oblique overaction improved from +3 to +1. None of the patients had any residual vertical deviation. There was elimination of compensatory head tilting in 5 patients and correction of compensatory face turns in 4 patients. One patient with mild up drifting of the involved eye also improved after the procedure. All patients expressed subjective satisfaction with the surgical outcome.

CONCLUSIONS: Transposition of the inferior oblique muscle belly effectively weakened mild to moderate inferior oblique overaction and corrected small primary position hypertropias. This procedure may be a useful addition to surgical treatment options in patients with small hypertropias associated with inferior oblique overaction. [J Pediatr Ophthalmol Strabismus. 2018;55(1):43-46.].