Purpose: The purpose of the present study is to evaluate the therapeutic effects of slanting muscle insertions for "A" and "V" exotropia.
Methods: We performed slanting recession and resection of medial or lateral rectus muscles. A slanting surgical incision creating a 3-4 mm difference between the upper and lower margins of the muscles was performed in 28 patients with "A" or "V" exotropia ( "V" exotropia, 16 patients; "A" exotropia, 12 patients). Cases of "V" exotropia with moderate or marked overaction of the inferior oblique muscle were excluded.
Results: "V" exotropia: The average "V" pattern was 17.9 prism diopters (Delta) before and 7.6 delta after the operation. Slanting surgery reduced the "V" pattern in 15 of the 16 "V" patients. The mean reduction was 10.3 Delta in the "V" pattern and 29.8 Delta in the upward gaze deviation. "A" exotropia: The average "A" pattern was 26.6 Delta before and 6.3 Delta after the operation. Slanting surgery reduced the "A" pattern in 8 of the 12 "A" patients. The mean reduction was 20.3 Delta in the "A" pattern and 36.4 Delta in the downward gaze deviation.
Conclusion: We conclude that the surgical technique of slanting muscle insertions for correcting exotropia of "A" pattern with superior oblique muscle overaction and "V" pattern without moderate or marked inferior oblique muscle overaction is suitable for reducing "A" and "V" patterns.