title: Action of botulinum toxin on isometric contraction of medial and lateral rectus muscles in esotropic or exotropic patients.
abstract: OBJECTIVE
  To study the action of botulinum toxin A on isometric contraction of the medial and lateral rectus muscles in esotropic or exotropic patients.
  
  
  METHODS
  Isometric contraction in patients with strabismus (exotropic and esotropic) and in volunteers without strabismus was compared 30 days after the use of botulinum toxin A.
  
  
  RESULTS
  Findings show that this drug has changed the strength ratio between direct agonist and antagonist muscles. This has promoted the displacement of the point of equilibrium between muscle strengths toward the nasal direction in esotropic cases, toward the temporal direction in exotropic cases, and subsequent deviation of the eye toward its primary position. The average achieved correction was approximately 10 prism diopters in both groups of patients.
  
  
  CONCLUSIONS
  In both exotropia and esotropia, the average variations in the induced points of equilibrium related to injection of botulinum toxin A were similar. This means that the greatest percentage of corrections happened in cases of small deviations.
authors.affiliation: University of Pernambuco, Recife, Brazil.
authors.forename: Ely Almeida
authors.initials: EA
authors.lastname: Santos
authors.forename: Rodrigo Pessoa Cavalcanti
authors.initials: RP
authors.lastname: Lira
authors.forename: Harley Edison Almaral
authors.initials: HE
authors.lastname: Bicas
authors.forename: Maria Isabelle Lynch
authors.initials: MI
authors.lastname: Gaete
mesh_terms: D000293:Adolescent; D000328:Adult; D019274:Botulinum Toxins, Type A / Q000008:administration & dosage / Q000627:therapeutic use*; D002648:Child; D004576:Electromyography; D004948:Esotropia / Q000188:drug therapy* / Q000503:physiopathology; D005099:Exotropia / Q000188:drug therapy* / Q000503:physiopathology; D005260:Female; D006801:Humans; D007273:Injections, Intramuscular; D007537:Isometric Contraction / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009465:Neuromuscular Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D009801:Oculomotor Muscles / Q000187:drug effects* / Q000503:physiopathology; D055815:Young Adult
chemical_list: D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A