Characteristics of childhood intermittent exotropia with and without DVD

Purpose: Although dissociated vertical deviation (DVD) is reported to occur rarely in children with intermittent exotropia (IXT), little is known regarding the clinical features of these children. The purpose of this study was to compare the demographic and clinical characteristics of children with intermittent exotropia and DVD to those without DVD. Methods: The medical records of all children diagnosed with intermittent exotropia at our institution from 1 January 2002, through 31 December 2018, who had 2 or more exams with 3 or more assessments of control, were retrospectively reviewed. Exotropic children with DVD were compared to those without DVD. Results: During the 17-year study period, 115 children met the inclusion criteria, of which 25 (21.7%) had DVD. Compared to the 90 exotropic children without DVD, children with IXT and DVD were more likely to have a motility disorder (p = .021), a worse mean distance control score (2.8 vs 2.4; p = .09), a larger mean angle of deviation (27.8 prism diopters [PD] vs 25.1 PD; p = .04), and a lower median stereopsis (200 secs vs 100 secs; p = .08). The children with DVD were more likely to have undergone surgery (p = .17) although there was no difference in the mean age at initial surgery between the two groups. Conclusions: The presence of dissociated vertical deviation in children with intermittent exotropia is associated with more motility disorders and worse binocular function compared to those without DVD. These children will likely require closer observation and earlier intervention.