Vertical shift of the medial rectus muscles in the treatment of A-pattern esotropia: Analysis of outcome

A retrospective study was performed on 18 consecutive patients with A- pattern esotropia and no apparent oblique muscle dysfunction, mechanical restriction, paresis, or previous muscle surgery. All patients underwent graded bilateral medial rectus recession for their esotropia with simultaneous vertical upshift to treat the A-pattern. The quantitative relationship between amount of upshift, amount of A-pattern correction, preoperative A-pattern, and preoperative esotropia was examined. We found that the amount of A-pattern correction was closely correlated with the size of the A-pattern preoperatively (r=0.83), independent of amount of upshift. While the change in A-pattern did correlate with the amount of the upshift (r=0.60), it was not a significant independent predictor of the surgical response. The amount of recession had little influence on the effectiveness of the procedure in correcting the vertical incomitance, and the transposition did not seem to affect the correction of the basic esotropia, adversely. We conclude that medial rectus recession with vertical upshift of the muscle insertions is an effective procedure for correcting the vertical incomitance in A-pattern esotropia, and that the amount of A-pattern correction achieved is determined primarily by the size of the preoperative A-pattern and not the amount of upshift.