title: Fixation preference and visual acuity testing in a population-based cohort of preschool children with amblyopia risk factors.
abstract: OBJECTIVE
  To compare the clinical assessment of fixation preference (FP) to visual acuity (VA) in a population-based sample of preschool children with amblyopia risk factors.
  
  
  METHODS
  Evaluation of diagnostic test in a population-based study.
  
  
  METHODS
  243 children with anisometropia and/or strabismus, aged 30 to 72 months, living in Los Angeles County, CA [corrected]
  
  
  METHODS
  Before measuring VA, FP testing was performed at near and usually without correction, using the binocular fixation pattern in children with strabismus >10 prism diopters (Delta), or the induced tropia test for children with strabismus <or=10Delta or without strabismus. We determined the sensitivity and specificity of FP testing for predicting unilateral amblyopia, defined by optotype VA, among children with amblyopia risk factors.
  
  
  METHODS
  Grade of FP.
  
  
  RESULTS
  Sensitivity of FP testing for amblyopia among children with anisometropia was 20% (9/44) and specificity was 94% (102/109). Among strabismic children, sensitivity was 69% (9/13; worse in children 30-47 than 48-72 months old) and specificity was 79% (70/89), with similar findings for esotropia and exotropia.
  
  
  CONCLUSIONS
  The ability of FP testing to correctly identify amblyopia in preschool children with amblyopia risk factors is poor. Clinicians should be wary of using FP as a surrogate measure of interocular difference in VA in young children.
  
  
  BACKGROUND
  The authors have no proprietary or commercial interest in any materials discussed in this article.
authors.affiliation: Doheny Eye Institute and the Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, California 90033-9224, USA.
authors.forename: Susan A
authors.initials: SA
authors.lastname: Cotter
authors.forename: Kristina
authors.initials: K
authors.lastname: Tarczy-Hornoch
authors.forename: Erin
authors.initials: E
authors.lastname: Song
authors.forename: Jesse
authors.initials: J
authors.lastname: Lin
authors.forename: Mark
authors.initials: M
authors.lastname: Borchert
authors.forename: Stanley P
authors.initials: SP
authors.lastname: Azen
authors.forename: Rohit
authors.initials: R
authors.lastname: Varma
mesh_terms: D000550:Amblyopia / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology; D002648:Child; D002675:Child, Preschool; D005189:False Positive Reactions; D005260:Female; D005403:Fixation, Ocular / Q000502:physiology*; D006801:Humans; D008297:Male; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012307:Risk Factors; D012680:Sensitivity and Specificity; D013285:Strabismus / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology; D014787:Vision Tests; D015348:Vision, Binocular / Q000502:physiology; D014792:Visual Acuity / Q000502:physiology*