Effect of inferior oblique anterior transposition in correcting vertical hyperdeviation in primary position

Abstract Objective To evaluate the effect of inferior oblique anterior transposition (IOAT) on improvement of vertical hyperdeviation in primary position. Methods This study was a retrospective review and included 35 eyes of 33 patients (18 males and 15 females). Patients with dissociated vertical deviation were not included in the study. Preoperative and postoperative average follow-up was 11.46 ± 11.73 and 11.43 ± 9.73 months, respectively. The eyes were divided into 5 groups according to the amount of transposition. Inferior oblique muscle was transpositioned 2 mm posterior to the inferior rectus insertion in group 1; 1 mm posterior to the inferior rectus insertion in group 2; parallel to the inferior rectus insertion in group 3; 1 mm anterior to the inferior rectus insertion in group 4; and 2 mm anterior to the inferior rectus insertion in group 5. Results The mean preoperative and postoperative vertical hyperdeviation were 16.52 ± 5.54 and 0.97 ± 2.34 prism diopters (PD), respectively. The mean preoperative vertical hyperdeviation in group 1, group 2, group 3, group 4, and group 5 was 11.0 ± 4.24, 12.88 ± 4.26, 16.63 ±3.50, 19.83 ± 2.71, and 25.5 ± 3.00 PD, respectively. Postoperatively, improvement in vertical hyperdeviation in group 1, group 2, group 3, group 4, and group 5 was 11.0 ± 4.24, 11.63 ± 3.20, 15.46 ± 3.19, 18.17 ± 2.23, and 25.5 ± 3.00 PD, respectively. The vertical hyperdeviation had improved 100% in group 1; 90.2% in group 2; 92.9% in group 3; 91.59% in group 4; and 100% in group 5. Conclusion IOAT surgery planned according to hyperdeviation amount has effective and predictable results in correcting vertical hyperdeviation in primary position.