We investigated the recommended minimum postoperative follow-up period for the determination of secondary corrective surgery for the consecutive esotropia (ET) and recurrent exotropia (XT) after the first intermittent XT surgery.

The medical records of 728 patients who underwent surgical treatment for intermittent XT between 2004 and 2009 with a minimum postoperative follow-up of 1 year were retrospectively reviewed. Each patient underwent a detailed sensory and motor examination, including measurements of near and distance stereoacuity, alternating-cover test, and extraocular muscle function testing. Consecutive ET was defined as esodeviation over 15 prism diopter (PD) at distance persisting for more than 6 months after surgery despite medical treatment. Recurrent XT was defined as exodeviation over 15 PD at distance after surgery despite medical treatment.

The mean age of the 728 patients at first surgery was 7.5 years (range, 22 months - 30 years). When only the motor outcome was considered, 663 patients (91.1%) had an orthrotropia at the final follow-up and 44 patients (6.0%) among consecutive ET patients and 21 patients (2.9%) who had a recurrent XT underwent secondary surgical correction. Binocularity decreased postoperatively in patients with consecutive ET ( p < 0.001), whereas the other patients demonstrated improved stereopsis postoperatively ( p = 0.041, 0.021). Patients with consecutive ET showed esodeviation over 10 PD when compared with orthotropia after 2 months postoperatively ( p = 0.005). At 6 months postoperatively, 17 (81.0%) of 21 patients with recurrent XT showed orthotropia with an exodeviation over 11 PD after 18 months postoperatively.

The success rate of surgical correction for intermittent XT showed a favorable outcome. However, careful concern for consecutive ET and recurrent XT are required in postoperative follow-up periods. Over-corrected or consecutive ETs need early surgical correction because no further improvement of ocular alignment will occur after 2 months postoperatively and delayed correction can result in poor sensory binocularity. Under-corrected or recurrent XT should be observed for an extended period because of the exotropic drift after surgery, thus requiring periodic long term follow-up for secondary surgery at least for 18 months postoperatively.