To define risk factors for and to analyze changes in hyperopic refractive error during development of postoperative exotropia (XT) after bilateral medial rectus (BMR) recession to treat infantile esotropia.

We retrospectively examined 50 patients with infantile esotropia who underwent BMR recession from January 2005 to December 2010. All were <10 years of age and underwent ≥36 months of follow-up. We recorded age at operation, the preoperative strabismus angle, the extent of medial rectus recession, strabismus status, pre- and post-operative changes in the refractive errors of both eyes, any postoperative overcorrection, any dissociated vertical deviation (DVD), and inferior oblique overaction (IOOA) status.

Consecutive XT developed in 18 (36%) patients. The preoperative refractive error was +0.90 ± 0.79 D in the consecutive XT group and +1.94 ± 1.48 D in the surgical success (SS) group ( p = 0.019). The extent of hyperopic decrease was significantly greater in the consecutive XT group than the SS group (consecutive XT group: 1.59 ± 1.38 D, SS group: 2.86 ± 1.97 D) at 3 years of post-operative follow-up ( p = 0.008). Postoperative IOOA was detected in 10 (70.5%) patients in the consecutive XT group and 3 (29.55%) in the SS group ( p = 0.002). No significant between-group difference in the incidence of overcorrection or DVD was apparent.

The presence of hyperopia (>+2.0 D) prior to BMR recession and a marked fall in the extent of hyperopia (−1.0 D/year) after recession may be associated with a high risk of consecutive XT. Thorough follow-up is necessary when IOOA develops after BMR recession.