Bilateral lateral rectus recession considering the tendon width in intermittent exotropia

The tendon width of the lateral rectus muscle can be a useful indicator of the effect of unilateral lateral rectus recession in intermittent exotropia. The aim of this study was to determine whether the tendon width of lateral rectus would be useful for predicting the effect of bilateral lateral rectus (BLR) recession.

We studied a total of 45 patients between 3 and 15 years of age who had undergone bilateral rectus recession for the basic type of intermittent exotropia. The actual effect of lateral recession was calculated by adding the absolute value of the angle of preoperative deviation and the postoperative deviation on the second day and dividing the figure by the total amount of recession. We then calculated the hypothetical effect of lateral rectus recession, considering the tendon width of each eye, and added the effects of both eyes. The hypothetical effects were defined as 3 PD when the tendon width was 8-8.5 mm; 3.5 PD when it was 7-7.5 mm; and 2.5 PD when it was 9-9.5 mm, based upon earlier statistical analysis. We compared both effects using a paired t-test.

The mean difference between the actual and the hypothetical effects of BLR recession in all patients was 2.88 PD (P=0.001, range: 0-5.50 PD). However, when the amount of preoperative exodeviation was below 25 PD, the differences were not statistically significant (P=0.086).

The tendon width may also be useful indicator in BLR recession if the preoperative exodeviation is below 25 PD.