Purpose: To analyze the effect of occlusion therapy in patients with early recurrence after intermittent exotropia surgery. Methods: The present study included 36 patients with an exodeviated angle of 10 prism diopters (PD) or more within 3 months after intermittent exotropia surgery. Eighteen patients (treatment group) performed alternating occlusion therapy for 3 hours per day for 6 months and the other 18 patients (control group) were followed up without any therapy. Age, visual acuity, deviated angle (before operation, at recurrence, and 3 and 6 months after recurrence), and binocularity were retrospectively analyzed in both groups. Results: Differences between the two groups in terms of age, visual acuity, score of binocularity, association with vertical strabismus or dissociated vertical deviation, period of recurrence and exodeviated angle at recurrence were not observed. Significant differences in change of deviated angle at a far distance were found 3 months after recurrence; 0.00 +/- 3.69 PD in the treatment group and +2.88 +/- 2.97 PD in the control group (p = 0.014) and at a near distance -1.33 +/- 5.13 PD in the treatment group and +3.22 +/- 3.99 PD in the control group (p = 0.005). Significant differences in the change of deviated angle were found after 6 months from recurrence at a far distance; +0.11 +/- 5.78 PD in the treatment group and +4.50 +/- 4.94 PD in the control group (p = 0.020), -0.56 +/- 5.71 PD in the treatment group and +3.94 +/- 6.46 PD in the control group at a near distance (p = 0.034). The binocularity index was not different between the two groups. Conclusions: Although in the present study, the mean angle of deviation was not decreased, alternating occlusion therapy 3 hours per day for 6 months may be helpful in reducing the amount of exodrift in patients with early recurrence within 3 months after intermittent exotropia surgery.
