The Efficacy of Anterior-Nasal Surgery in Managing Inferior Oblique Overaction either with DVD or with V Pattern

Objective: This study aims at determining the efficacy of anterior and nasal transposition of Inferior Oblique to manage dissociated vertical deviation and vertically incomitant horizontal strabismus (V pattern). Method: This study was both prospective and uncontrolled; it included 60 patients who suffered from inferior oblique overaction. The participants were divided into two groups: Group A had 30 patients with vertically incomitant horizontal strabismus while group B had 30 patients with dissociated vertical deviation. Preoperative examination included: Assessment of vision, ductions and versions in the six cardinal directions of gaze and severity of IOOA graded from 0 to +4. The percentage of dissociated vertical deviation was measured using the prism under cover test in primary position. Follow-up visits occurred in the following intervals: After one week, one month, four months, and six months respectively. In each follow-up visit, the measurements of ductions, versions, and alignment in primary position were recorded. Results: Group A showed no pattern in 93.3% of cases postoperatively while 6.7% of cases developed insignificant V pattern (0.8 ± 2.9 ΔD), with statistically significant difference between the pre-and post-operative values (pvalue< 0.001). Meanwhile, group B showed a complete resolution of DVD in 100% of cases with preoperative (DVD<15 ΔD) and in 20% of cases with preoperative DVD ≥ 15 ΔD; the remaining cases had residual DVD (3.6 ± 4.1 ΔD). Conclusion: Anterior-nasal transposition of the Inferior Oblique muscle is an effective procedure for cases with severe or recurrent inferior oblique overaction when other standard procedures of Inferior Oblique muscle fail. For DVD ≥ 15 ΔD, we recommend a combined anterior-nasal transposition of inferior oblique with superior rectus recession.