Superior Oblique Muscle Overaction A Pattern: Diagnosis And Management

[Purpose] To evaluate the efficacy of the management of superior oblique muscle by tenectomy as weakening procedure of overacting superior oblique and its effect on correction of A pattern, vertical deviation in adduction and dorsoadduction, and cyclodeviation. [Methods] In a prospective, institution-based study, we selected 13 patients who had superior oblique overaction associated with significant "A" pattern (>10 PD) were studied. Combined the superior oblique muscle tenectomy with the horizontal muscles surgery was performed. Out of 5 patients from total 13 who had Helveston syndrome (Apattern exotropia, bilateral superior oblique overaction, dissociated vertical deviation), underwent to asymmetric superior rectus recession. We observed such parameters like: change in A pattern; effect on vertical deviation in adduction and dorsoadduction; superior oblique overaction; dissociated vertical deviation and cyclodeviation. Fromthis observation, we could evaluate the influence of tenectomy bymeasuring the rotating angle between optic disc and macula infunduscopy.[Results] The weakening procedure of overacting superior obliqueproduce 100% reduction in "A" pattern, indicating equal effect in collapse of A phenomenom 50 PD in bilateral surgery. The whole displacement of the horizontal muscle insertion width induced 30 PD of the collapse of "A" pattern.The funduscopy image show a maximal rotating angle of 23. 51 for tenectomized overacting superior oblique eyeinsignificant torsion for horizontal muscle displaced vertically.[Conclusion] We found that the tenectomy procedure offered the most advantage in the reduction of "A" pattern and a incyclotorsion for fundus image. The cyclotorsion does not correlate to the hyperfunction of superior oblique muscle by objective examination. Recognition of such of incomitant dissociated vertical deviation is important to choose appropriate surgical management. Early surgery result high probability to return to normal retinal correspondance and binocular vision.