The Dose-Response Relationship of Vertical Rectus Muscle Recession

Purpose: To determine the dose-response relationship of vertical rectus recession according to disease entity. Methods: We retrospectively reviewed the charts of 28 patients who underwent vertical rectus recession and who had been followed up for at least 6 months. The patients who underwent oblique muscle surgery at the same time were excluded. Results: The disease entities included paralytic strabismus in 8 eyes (26%), dissociated vertical deviation in 11 (35%), and isolated vertical strabismus with no other known causes in 12 (39%). The mean effect in prism diopters, per millimeter of recession (PD/mm), was 3.10±1.52 in the immediate postoperative period and 2.94±1.64 at the last follow-up, which was not statistically significant. At the last follow-up, the dose response of isolated vertical deviation was 3.78±1.70 PD/mm, significantly higher than that seen in the others. The dose response in paralytic strabismus was 3.24±0.63 PD/mm, and that in dissociated vertical deviation was 1.82±1.51 PD/mm. Conclusions: There was no significant difference between the dose response in the immediate postoperative period and that at the last follow-up visit. Regarding disease entity, the dose response of isolated vertical deviation was largest as 3.78±1.70 PD/mm, and that of dissociated vertical deviation was smallest as 1.82±1.51 PD/mm.