Purpose: Anterior transposition of the inferior oblique muscle was reported to be an effective treatment for dissociated vertical deviation (DVD), Our aim is to evaluate the efficacy of this surgical procedure in a series of patients with DVD alone and DVD with concurrent overactive inferior oblique muscle and to compare the results.
Method: Nineteen eyes with DVD only (group one) and fifteen eyes with DVD and concurrent inferior oblique overaction (group two) underwent IOAT. The amount of DVD and inferior oblique overaction (IOOA) before and after the operation was registered and statistically analyzed.
Results: The mean follow up time for the first and the second groups were 9.4 and 9 months respectively. Overall in five of seven eyes with DVD of more than 15PD, the residual DVD following the operation were more than five PD .Whereas in the 27 patients with DVD less than or equal to 15 PD the residual deviation were below 5PD (P value=0.014).
Conclusion: IOAT is an effective method for correcting DVD with and without IOOA especially in deviations under 15 PD. In DVD> 15 PD it seems that IOAT alone is unable to correct or reduce DVD satisfactorily.