A comparative study of the effectiveness of disinsertion and anterior transposition of the inferior oblique in the treatment of unilateral superior oblique palsy.

PURPOSE: To compare the effectiveness of disinsertion of the inferior oblique muscle (DIO) with anterior transposition of the inferior oblique muscle (ATIO) in the treatment of vertical deviations resulting from superior oblique palsy.

METHODS

In this prospective randomized study, 22 patients with unilateral superior oblique palsy were evaluated. Eleven patients underwent the DIO procedure (DIO group), and the other eleven underwent the ATIO procedure (ATIO group). Statistics were analyzed using the Wilcoxon and Mann-Whitney U tests.

RESULTS

The mean preoperative primary-position hypertropia was 22.2 +/- 6.2 prism diopters (Delta) in the DIO group and 23.1 +/- 6.6 Delta in the ATIO group; the mean preoperative hypertropia in adduction was 31.7 +/- 6.9 Delta in the DIO group and 31.8 +/- 8.1 Delta in the ATIO group. The mean follow-up was 18.8 months (SD: 10.2, range: 6-40 months). The mean reduction of hypertropia in primary-position in the ATIO group (mean: 18.5 +/- 3.9 Delta) was found to be significantly greater than in the DIO group (mean: 13.3 +/- 1.9 Delta) (p = 0.001). Even though the mean reduction of hypertropia in adduction in the ATIO group (mean: 27.7 +/- 9.6 Delta) was greater than in the DIO group (mean: 20.6 +/- 6.2 Delta), no statistically significant difference was found (p = 0.067). There was residual hypertropia in three (27.3%) patients who underwent the DIO procedure. No major postoperative complication was encountered in any of the patients.

CONCLUSION

In vertical deviations resulting from superior oblique palsy, ATIO was found to be more effective than DIO in the reduction of primary-position hypertropia.