The Minimal Postoperative Follow-Up Period to Determine Secondary Surgery in Patients with Intermittent Exotropia

ABSTRACT

PURPOSE: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.