To investigate clinical characteristics of constant exotropia patients with a previous history of intermittent exotropia.

Constant exotropia patients (CXT) with a previous history of intermittency, and intermittent exotropia patients (X [T]) who had undergone surgery for exotropia were included in the present study. Patching therapy of the fixating eye was performed for all patients. Surgical results, the effect of patching, lateral incomitancy, and suppression were retrospectively reviewed and compared between the 2 groups.

The number of CXT was 51 and X (T) was 84. The angles of deviation at the initial visit and at surgery were significantly larger in CXT. After 3 months of patching therapy, there was no difference between the 2 groups in the reduction of distant angle of deviation. However, the reduction of near angle of deviation was 0.29 ± 5.44 in CXT and 4.42 ± 6.26 Δ in X (T), which was significantly different ( p = 0.04). Lateral incomitancy was observed in 7.8% of CXT and 34.5% of X (T) ( p < 0.001). The angles of deviation at the final visit and surgical success rate were not different between the groups. Preoperative suppression at distant was found in 100% of CXT and 88.7% of X (T), and postoperative suppression was in 17.6% and 18.3%, respectively.

The surgical success rate and postoperative suppression were not different between constant exotropia and intermittent exotropia. However, the frequency of lateral incomitancy and the response to the patching therapy was lower in constant exotropia.