Anteriorization of the inferior oblique muscle versus anteriorization and resection for asymmetrical dissociated vertical deviation.

Purpose: To compare the efficacy of two methods: first, bilateral symmetric anteriorization of the inferior oblique muscle and second: combined resection and anteriorization of the inferior oblique (IO) muscle for asymmetric dissociated vertical deviation (DVD).

Design: Prospective randomized clinical trial.

Methods: This study included fifty-four patients presenting with bilateral asymmetric DVD and inferior oblique overaction (IOOA). Two equal groups were randomly allocated by odd and even number distribution. Twenty-seven patients underwent bilateral symmetric anteriorization of the IO muscle and twenty-seven patients underwent anteriorization of the IO of one eye and anteriorization with IO resection in the eye with the larger deviation. According to the difference in measured DVD between the two eyes whether less or more than 5 PD; a 3 or 5 mm resection was done, respectively.

Results: The mean post-operative reduction of DVD in the anteriorization group was 9.19 ± 3.40 PD in the right eye and 8.78 ± 4.17 PD in the left eye, which were highly significant. (p-value .0002). The resection group had a mean post-operative DVD reduction of 11.7 ± 2.74 PD in resected eyes and 7.3 ± 3.72 PD in non-resected eyes. These reductions were also highly significant (p-value 0.0001). Reduction of inter-ocular difference between both groups failed to show a statistical difference (p-value 0.285). The IOOA was significantly reduced in both groups. Improvement in the average post-operative DVD between the two groups and the post-operative improvement in IOOA failed to show a statistically significant difference (p-value 0.265 and 0.804 respectively) which showed that both procedures are effective.

Conclusion: Both surgical modalities are effective in managing asymmetric dissociated vertical deviation associated with IOOA.