Factors Influencing the Prevalence of Amblyopia in Children with Anisometropia

PURPOSE To evaluate factors that can influence the prevalence of amblyopia in children with anisometropia. METHODS We retrospectively reviewed the records of 63 children 2 to 13 years of age who had anisometropic amblyopia with a difference in the refractive errors between the eyes of at least two diopters (D). The type of anisometropia (myopia, hyperopia, and astigmatism), degree of anisometropia (<2-3 D, <3-4 D, or >4 D), best corrected visual acuity (BCVA) of the amblyopic eye at the time of initial examination, BCVA differences between sound and amblyopic eyes, whether or not occlusion therapy was performed, compliance with occlusion therapy, and the patient's age when eyeglasses were first worn were investigated. RESULTS There was an increase in the risk of amblyopia with increased magnitude of anisometropia (p=0.021). The prevalence of amblyopia was higher in the BCVA <20/40 group and in patients with BCVA differences >4 lines between sound and amblyopic eyes (p=0.008 and p=0.045, respectively). There was no statistical relationship between the prevalence of amblyopia and the type of anisometropia or the age when eyeglasses were first worn. Poor compliance with occlusion therapy was less likely to achieve successful outcome (p=0.015). CONCLUSIONS Eyes with poor initial visual acuities of <20/40, a high magnitude of anisometropia, and a >4 line difference in the BCVA between sound and amblyopic eyes at the initial visit may require active treatment.