AIM: To investigate the effect and binocular alignment of unilateral recession-resection(R-R)procedure in patients with insufficient convergence intermittent exotropia(IXT).

METHODS: Totally 45 patients with insufficient convergence IXT were operated with unilateral R-R procedure. Binocular alignment was accessed 1d postoperative and 2wk postoperative. Statistical analysis was performed on squint at different time points.

RESULTS: All 45 patients with insufficient convergence IXT were operated with unilateral R-R procedure. On the 1^st day after surgery, an overcorrection of 8.27±7.17PD at distance and 2.40±8.86PD at near were seen. On the 2wk after surgery. An under correction of 1.18±6.98PD at distance and 4.36±7.83PD at near were seen. Within 2wk after surgery, the average exo-drift at distance was 9.45±6.40PD, and at near was 6.77±7.92PD. There was statistically significant difference between exo-drift at distance and near, and a positive correlation was discovered. The difference of near-distance squint at postoperative(3.18±5.60PD)was significantly lower than that of preoperative(7.65±6.55PD), and there was a positive correlation between them.

CONCLUSION: Unilateral R-R procedure is appropriate for patients with insufficient convergence IXT. An appropriate increase of medial rectus strengthening can reduce postoperative near-distance squint difference and does not change the tension of medial rectus and lateral rectus. There was a synchronized exo-drift both at distance and near. The postoperative exo-drift at distance was 10PD and we believe a 10PD overcorrection shortly after operation may be beneficial to the long-term binocular alignment.