The use of vertical offsets with horizontal strabismus surgery.

A series of 83 patients had vertical displacement of the horizontal rectus muscle insertions monocularly along with recession-resection surgery to correct comitant, vertical strabismus coexisting with a horizontal deviation. Using a surgical plan of approximately 1 mm of displacement of both the medial and lateral rectus insertions to correct each prism diopter (PD) of vertical deviation, 67% of patients had no residual vertical strabismus, and 80% had 2 PD or less of vertical strabismus. Mean follow-up time was 18 months (minimum, 6 weeks). Little change was noted in the vertical deviation after the 1-month postoperative examination. Transposition appeared to have no effect on the results of surgery for the horizontal strabismus.