The Prevalence of Dissociated Horizontal Deviations in Congenital Esotropia

Dissociated horizontal deviation (DHD) has recently been theorized to be an abducting component of dissociated vertical deviation (DVD).1 As DVD is most commonly associated with congenital esotropia, the prevalence of DHD in congenital esotropia was evaluated. The effect of surgical correction of the vertical component of DVD upon DHD was also investigated. This study proposes that patients with a history of congenital esotropia who now appear to have a postoperative exotropia in the presence of DVD may, in fact, have DHD rather than exotropia.Records of four hundred and forty patients who underwent surgery for the treatment of congenital esotropia were reviewed. Twenty-two patients were found to have a true DHD, giving a prevalence of 5.0%. Ten of these patients had surgery for DVD. Four patients were diagnosed with true DHD following DVD surgery. Eleven patients (2.5%) had a pseudo DHD secondary to either anisometropia or a surgically induced limitation of ocular motility.Sixty-nine (15.7%) of the post-surgical congenital eso-tropes appeared to have secondary exotropia. As some patients in this group may have undiagnosed DHD, the prevalence of this condition in association with congenital esotropia may be higher than that reported in this study.