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, mechanic al restriction, paresis, or previous muscle surgery. All patients unde rwent graded bilateral medial rectus recession for their esotropia wit h simultaneous vertical upshift to treat the A-pattern. The quantitati ve relationship between amount of upshift, amount of A-pattern correct ion, preoperative A-pattern, and preoperative esotropia was examined. We found that the amount of A-pattern correction was closely correlate d with the size of the A-pattern preoperatively (r = 0.83), independen t of amount of upshift. While the change in A-pattern did correlate wi th the amount of the upshift (r=0.60), it was not a significant indepe ndent predictor of the surgical response. The amount of recession had little influence on the effectiveness of the procedure in correcting t he vertical incomitance, and the transposition did not seem to affect the correction of the basic esotropia, adversely. We conclude that med ial rectus recession with vertical upshift of the muscle insertions is an effective procedure for correcting the vertical incomitance in A-p attern 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.