Outcomes of Augmented Surgery Performed after Simplified Prism Adaptation Testing in Patients with Intermittent Exotropia

ABSTRACT

PURPOSE@#We explored whether the deviation angle in patients with intermittent exotropia was greater when the prism adaptation test was used rather than the prism cover test.@*METHODS@#From January 2013 to December 2017, we performed the prism cover and adaptation tests on patients with intermittent exotropia. If the deviation angle increased by more than 5 PD after the prism adaptation test, surgery was performed. The outcomes of patients followed-up for more than 1 year after surgery were analyzed retrospectively.@*RESULTS@#In total, 76 of 100 patients (76.0%) exhibited deviation angle increases of over 5 PD, the mean increase was 9.8 ± 6.3 prism diopters (PD) for near vision and 3.6 ± 3.5 PD for distance vision. Satisfactory motor alignment was achieved in 57 patients; 42 were undercorrected and 1 was overcorrected. The success rate was 62.5% in the non-responder group (n = 24, patients in whom the deviation angle did not increase after prism adaptation) and 68.9% in the full augmentation group (n = 45, in whom the deviation angle was increased). In the partial augmentation group (n = 31), where the surgical target was a 50% increase in the deviation angle, the success rate was lower than in the other groups.@*CONCLUSIONS@#The preoperative prism adaptation test can be used to determine the angle of deviation and improves the surgical outcomes of patients with intermittent exotropia.