Combined resection and anterior transposition of the inferior oblique muscle for the treatment of moderate to large dissociated vertical deviation associated with inferior oblique muscle overaction

Abstract

Purpose: To evaluate the efficacy of combined resection and anterior transposition of the inferior oblique muscle for the treatment of eyes with a moderate to large amount of dissociated vertical deviation (DVD; 10 or more PD) associated with overaction of the inferior oblique muscle.

Patients and methods: Surgery was performed on 15 eyes of 9 patients with moderate to large DVD associated with overaction of the inferior oblique muscle. The inferior oblique muscle was disinserted from the sclera and 4 mm of its distal end was resected. It was transposed to a position 1 mm anterior to the lateral border of the inferior rectus muscle insertion. The prism under cover test was used to measure the DVD. Overaction of the inferior oblique muscle was graded on a 4-point scale of 1+ to 4+. The surgical results were evaluated at 1 month and 1 year after surgery.

Results: Preoperatively, the mean DVD measured 16.6 PD. It had decreased to 1.3 PD 1 month after the operation and to 2.6 PD 1 year after the operation. Before the operation, 5 eyes had 4+ and 10 eyes had 3+ inferior oblique muscle overaction. One year after the operation, only 3 eyes had 1+ inferior oblique muscle overaction. None of the patients developed diplopia or hypotropia in the primary position. Mild limitation of elevation has been noticed in 20% of the eyes.

Conclusion: Combined resection and anterior transposition of the inferior oblique muscle is an effective treatment for moderate to large DVD associated with overaction of the inferior oblique muscle.