Amblyopia in astigmatic preschool children

Best-corrected recognition acuity (Lea Symbols chart) and best-corrected acuity for vertical and horizontal gratings was measured in 155 astigmatic and 338 non-astigmatic (<1.50 D cylinder) 3- to 5-year-old children. Reduced best-corrected recognition acuity was shown by children with simple/compound myopic or mixed astigmatism and by children with simple/compound hyperopic astigmatism. Magnitude of the recognition acuity deficit was correlated with amount of astigmatism. Meridional amblyopia (difference in best-corrected acuity for vertical vs horizontal gratings) was present in children with simple/compound myopic or mixed astigmatism, due to reduced acuity for horizontal gratings. There was no correlation between magnitude of meridional amblyopia and amount of astigmatism. Children with simple/compound hyperopic astigmatism showed no meridional amblyopia, but did show reduced acuity for both grating orientations. These results suggest that the neural changes that lead to amblyopia occur prior to age 3- to 5 years in astigmatic children.