title: [Clinical classification of variable angle exotrophy].
abstract: BACKGROUND
  Variable exotropia is determined by a series of mechanisms that provide different clinical characteristics to outline individual therapy. There is no specific categorization that can identify such an entity. A clinical classification is proposed that includes different clinical features in accordance with the mechanisms involved in the variability genesis of such exotropias.
  
  
  METHODS
  Patients with a diagnosis of variable angle exotropia without previous surgery were included. A complete ophthalmic and strabismus exploration was performed. Variability characteristics were studied and grouped by entries in the classification proposed.
  
  
  RESULTS
  Ninety patients were examined from the Pediatric Ophthalmology and Strabismus Unit of the General Hospital of Mexico O.D., with a diagnosis of variable angle exotropia. The following forms of presentations were found: secondary variable angle exotropia due to neurological alteration in 32 cases (35.5%), secondary variable angle exotropia due to monocular bad vision in 19 cases (21.2%), dissociated horizontal deviation in 14 cases (15.5%), mixed variable angle exotropia in 22 cases (4.5%) and primary variable angle exotropia in 3 cases (3.33%).
  
  
  CONCLUSIONS
  This classification allows categorization of all patients of variable angle exotropia into proposed categories. The most common mechanism responsible for variability is neurological alteration. Primary variable angle exotropias are rare and are present in a minimum percentage.
authors.affiliation: Clínica de Oftalmología Pediátrica y Estrabismo, Servicio de Oftalmología del Hospital General de México, O.D., Cuauhtémoc, 03100 México, Mexico. mearroyo1@prodigy.net.mx
authors.forename: María Estela
authors.initials: ME
authors.lastname: Arroyo-Yllanes
authors.forename: Déborah Itzel
authors.initials: DI
authors.lastname: Osorio-González
authors.forename: José Fernando
authors.initials: JF
authors.lastname: Pérez-Pérez
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D005099:Exotropia / Q000145:classification*; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D055815:Young Adult