'Largest angle to target' in surgery for intermittent exotropia

Purpose To evaluate the safety of the approach based on the notion that the surgical dose for intermittent exotropia should be based on the largest angle ever measured. Design Prospective case series of 33 patients. Methods A total of 33 patients with intermittent exotropia, in whom angles of misalignment at distance or near showed a difference of 15 prism diopters (PD) or more among visits, were included. All the patients were treated by bilateral lateral rectus recession by the same surgeon (JMH), and all were followed up for a minimum of 6 months postoperatively. Short- and long-term surgical results after the initial procedure for intermittent exotropia were analysed. Results The short-term average result at a postoperative 1 week was 9.3 PD esotropia at distance ( range 30 esotropia - 16 exotropia). The long-term average results postoperative 6 or 9 months were 4.8 PD exotropia at distance ( range 12 esotropia - 30 exotropia). At the last follow-up, no overcorrection over 2 PD esophoria at distance was found, and 9 PD of intermittent esotropia and esophoria at near was observed in two patients, respectively. Conclusions The strategy of surgical dose for intermittent exotropia based on the largest angle ever measured did not result in overcorrections and is believed to be safe.