The clinical profile of amblyopia in children younger than 3 years of age.

PURPOSE: 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.