title: Comparison of clinical features between two different types of exotropia before 12 months of age based on stereopsis outcome.
abstract: OBJECTIVE
  To compare the clinical outcomes and characteristics of 2 different types of early-onset exotropia on the basis of stereopsis outcome.
  
  
  METHODS
  Retrospective case series.
  
  
  METHODS
  A total of 24 patients with newly diagnosed exotropia before 12 months of age and at least 1 year of follow-up after surgery.
  
  
  METHODS
  The clinical records of all patients were reviewed. Patients were divided into 2 groups according to stereopsis. The presumable early-onset intermittent exotropia (EIE) group was composed of 6 patients (25%) who showed excellent stereopsis of ≥60 arc seconds. The primary infantile exotropia (PIE) group was composed of 18 patients (75%) who showed stereopsis of ≤100 arc seconds. We compared the preoperative and postoperative clinical features of the 2 groups.
  
  
  METHODS
  The age at onset and visit, age at surgery, constancy before surgery, preoperative and postoperative angles of deviation, distant suppression, reoperation rate, and presence of dissociative vertical deviation (DVD) and inferior oblique overaction (IOOA).
  
  
  RESULTS
  The age at the stereopsis test was 6.8 years in the EIE group and 6.4 years in the PIE group (P=0.41). There was no statistical difference in the mean preoperative exodeviation (32.8 prism diopters [PD] in the EIE group vs. 34.7 PD in the PIE group, P=0.58) and postoperative deviation at the stereopsis test (1.0 PD in the EIE group vs. 2.0 PD in the PIE group, P=0.97). The reoperation rate was 33% in the EIE group and 27% in the PIE group (P=1.00). There was no statistical difference in constancy between the EIE and PIE groups (33% vs. 56%, respectively, P=0.64). However, DVD (61%) and IOOA (56%) were noted only in the PIE group (P=0.016, P=0.024, respectively), and distant suppression was noted only in the PIE group (61%, P=0.016).
  
  
  CONCLUSIONS
  The results indicate that excellent sensory outcome was observed in only 25% of patients with exotropia before 12 months of age, but motor outcome and reoperation rate were not different between the 2 types of exotropia. We observed DVD, IOOA, and distant suppression only in the PIE group.
  
  
  BACKGROUND
  The author(s) have no proprietary or commercial interest in any materials discussed in this article.
authors.affiliation: Department of Ophthalmology, Korea University College of Medicine, Seoul, Korea.
authors.forename: Yong-Min
authors.initials: YM
authors.lastname: Choi
authors.forename: Seung-Hyun
authors.initials: SH
authors.lastname: Kim
mesh_terms: D000293:Adolescent; D017668:Age of Onset; D002648:Child; D002675:Child, Preschool; D003867:Depth Perception / Q000502:physiology*; D005099:Exotropia / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D009801:Oculomotor Muscles / Q000503:physiopathology / Q000601:surgery; D012086:Reoperation; D012189:Retrospective Studies; D016896:Treatment Outcome; D015348:Vision, Binocular / Q000502:physiology