title: The clinical profile of amblyopia in children younger than 3 years of age.
abstract: OBJECTIVE
  Amblyopia in children ≥3 years has been well described, but less is known about amblyopia in children <3 years of age. Here we describe the clinical characteristics of a large cohort of children <3 years of age with amblyopia and compare them with a previously described Pediatric Eye Disease Investigator Group amblyopic cohort aged 3 to 6 years.
  
  
  METHODS
  A total of 250 consecutive children with amblyopia <3 years were referred by 16 pediatric ophthalmologists.
  
  
  RESULTS
  The mean age at the initial diagnosis of amblyopia was 1.2 ± 0.7 years. The cause of amblyopia was strabismus in 82%, anisometropia in 5%, and combined mechanism in 13%. Compared with the 3- to 6-year-old cohort, the proportion of amblyopia attributable to strabismus was significantly greater (p < 0.001), whereas both anisometropia and combined mechanism amblyopia were significantly less common (p < 0.001). Overall, 61% of amblyopia was diagnosed at the same visit during which strabismus and/or anisometropia was initially diagnosed; an additional 21% of amblyopia was diagnosed at the first follow-up visit 1 to 3 months later. Compared with the 3- to 6-year-old cohort, amblyopic eye refractive error was significantly lower.
  
  
  CONCLUSIONS
  Strabismic amblyopia was diagnosed much more commonly than anisometropic and combined-mechanism amblyopia in children <3 years. Anisometropic amblyopia may be difficult to detect in children <3 years, and/or strabismic amblyopia may be overdiagnosed by fixation preference. Alternatively, anisometropia may develop more commonly after 3 years of age or may require greater duration to cause amblyopia.
authors.affiliation: Retina Foundation of the Southwest, Dallas, Texas 75231, USA. ebirch@retinafoundation.org
authors.forename: Eileen E
authors.initials: EE
authors.lastname: Birch
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Holmes
mesh_terms: D017677:Age Distribution; D000550:Amblyopia / Q000175:diagnosis* / Q000453:epidemiology*; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D005403:Fixation, Ocular; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D008297:Male; D015995:Prevalence; D012030:Refractive Errors / Q000175:diagnosis / Q000453:epidemiology; D017678:Sex Distribution; D013285:Strabismus / Q000175:diagnosis* / Q000453:epidemiology*; D014787:Vision Tests / Q000379:methods