Purpose: Horizontal strabismus is commonly associated with vertical deviations which can be a result of a dysfunction of the vertical rectus, oblique muscle or both. Overaction of the superior oblique muscle (SO) results in hypotropia (HoT) in primary position of gaze (PP). The aim of this study was to evaluate the correction of HoT in PP after unilateral tenectomy of the superior oblique muscle close to its scleral insertion. Patients and Methods: We retrospectively studied, from 1977 until 1996, charts of 15 patients with SO overaction and hypotropia in PP greater than 4D who underwent unilateral superior oblique tenectomy close to its insertion at Hospital Santa Casa de São Paulo (12 patients), University of Santo Amaro (2 patients) and private clinic of one of the authors (CSD, 1 patient). The mean preoperative deviation in PP was 9D. The mean preoperative superior oblique overaction was 1.7 (measured by a cross system rating). Results: The mean correction of the HoT was 4.67D ± 5.09D (-5D to 15D), (H = 6.032; p = 0.014). The mean correction of SO overaction was 0.87 ± 0.88 + (0 - 2). According to the horizontal deviation, ET and XT, there was no significant mdifference in the correction of the HoT. Conclusion: For HoT of 15D or less we found a mean correction of 51.82% of its preoperative value. Unilateral tenectomy has shown to be an effective technique for the correction of vertical deviation in PP in our study.
Strabismus; Oblique superior muscle; Tenectomy
