The Outcome of Graded Inferior Oblique Recession in the Congenital Unilateral Superior Oblique Palsy

PURPOSE: To examine changes in vertical deviation and improvement in head tilt after graded inferior oblique (IO) recession surgery in patients with congenital unilateral superior oblique palsy (SOP). Frequency of inferior oblique overaction (IOOA) or bilateral SOP in the contralateral eye after surgery was also investigated. METHODS: We retrospectively reviewed medical records of 65 patients who had undergone graded IO recession surgery in unilateral congenital SOP with at least 1 year of postoperative follow-up. Postoperative vertical deviation was classified as excellent (under 3 prism diopters, PD), good (4-7 PD) or poor (over 8 PD). The occurrence of IOOA was considered if more than 2 IOOAs were observed in the contralateral eye after surgery. RESULTS: Forty-five of the 65 patients (69%) obtained excellent results and 67.3% had improvement in head tilt after surgery. IOOA in the contralateral eye was not observed in any patients before surgery. Postoperative IOOA in the contralateral eye occurred in 9 patients (13.8%) and a diagnosis of masked bilateral SOP was made in 1 patient (1.5%). CONCLUSIONS: The graded IO recession procedures are considered to be an effective surgical method for the treatment of unilateral congenital SOP. However, IOOA or masked bilateral SOP occurring in the contralateral eye was observed in 15.3% of the patients undergoing surgery.

Superior Oblique Palsy

I reviewed charts of 26 patients with superior oblique palsy who had been treated surgically. Diagnosis of superior oblique palsy was based on the Bielschowsky head tilt test(BHT) and overacting inferior oblique muscle. Four patients(15%) were diagnosed as having bilateral superior oblique palsy, and 22 patients(85%) were diagnosed as monocular superior oblique palsy. After myectomy of the overacting inferior oblique muscle, 6(27%) out of 22 patients initially diagnosed as monocular superior oblique palsy deveioped findings of superior oblique palsy on the opposite eye; these patients were considered as having masked bilateral superior oblique palsy. Among the 16 patients with unilateral superior oblique palsy, 11 patients(69%) showed negative BHT, 4 patients(25%) showed equivocal BHT and 1 patient(6%) still showed positive BET after surgery. Among the 14 patients who could be followed up for more than 3 months after the operation, 11 patients(79%) showed negative BHT, 2 patients(14.%) showed equivocal BHT, and 1 patient(7%) showed positive BHT. According to these results, the overacting inferior oblique muscle in superior oblique palsy plays a very important role in the elevation of the eye on ipsilateral head tilt, and the mechanism of the BHT classically described should be reconsidered. The primary operation was inferior oblique myectomy and secondary or tertiary operations were inferior oblique myectomy, marginal myotomy or superior rectus recession on the same or the other eye.