title: The improving outcomes in intermittent exotropia study: outcomes at 2 years after diagnosis in an observational cohort.
abstract: BACKGROUND
  The purpose of this study was to investigate current patterns of management and outcomes of intermittent distance exotropia [X(T)] in the UK.
  
  
  METHODS
  This was an observational cohort study which recruited 460 children aged < 12 years with previously untreated X(T). Eligible subjects were enrolled from 26 UK hospital ophthalmology clinics between May 2005 and December 2006. Over a 2-year period of follow-up, clinical data were prospectively recorded at standard intervals from enrolment. Data collected included angle, near stereoacuity, visual acuity, control of X(T) measured with the Newcastle Control Score (NCS), and treatment. The main outcome measures were change in clinical outcomes (angle, stereoacuity, visual acuity and NCS) in treated and untreated X(T), 2 years from enrolment (or, where applicable, 6 months after surgery). Change over time was tested using the chi-square test for categorical, Wilcoxon test for non-parametric and paired-samples t-test for parametric data.
  
  
  RESULTS
  At follow-up, data were available for 371 children (81% of the original cohort). Of these: 53% (195) had no treatment; 17% (63) had treatment for reduced visual acuity only (pure refractive error and amblyopia); 13% (50) had non surgical treatment for control (spectacle lenses, occlusion, prisms, exercises) and 17% (63) had surgery. Only 0.5% (2/371) children developed constant exotropia. The surgically treated group was the only group with clinically significant improvements in angle or NCS. However, 8% (5) of those treated surgically required second procedures for overcorrection within 6 months of the initial procedure and at 6-month follow-up 21% (13) were overcorrected.
  
  
  CONCLUSIONS
  Many children in the UK with X(T) receive active monitoring only. Deterioration to constant exotropia, with or without treatment, is rare. Surgery appears effective in improving angle of X(T) and NCS, but rates of overcorrection are high.
authors.affiliation: Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, UK. Deborah.Buck@ncl.ac.uk
authors.forename: Deborah
authors.initials: D
authors.lastname: Buck
authors.forename: Christine J
authors.initials: CJ
authors.lastname: Powell
authors.forename: Jugnoo
authors.initials: J
authors.lastname: Rahi
authors.forename: Phillippa
authors.initials: P
authors.lastname: Cumberland
authors.forename: Peter
authors.initials: P
authors.lastname: Tiffin
authors.forename: Robert
authors.initials: R
authors.lastname: Taylor
authors.forename: John
authors.initials: J
authors.lastname: Sloper
authors.forename: Helen
authors.initials: H
authors.lastname: Davis
authors.forename: Emma
authors.initials: E
authors.lastname: Dawson
authors.forename: Michael P
authors.initials: MP
authors.lastname: Clarke
mesh_terms: D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003867:Depth Perception / Q000502:physiology; D005099:Exotropia / Q000503:physiopathology / Q000628:therapy*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D017063:Outcome Assessment, Health Care; D006113:United Kingdom; D015348:Vision, Binocular / Q000502:physiology; D014792:Visual Acuity / Q000502:physiology