Amblyopia in astigmatic infants and toddlers

Abstract

Purpose: To determine whether reduced astigmatism-corrected acuity for vertical (V) and/or horizontal (H) gratings and/or meridional amblyopia (MA) are present before 3 years of age in children who have with-the-rule astigmatism.

Methods: Subjects were 448 children, 6 months through 2 years of age with no known ocular abnormalities other than with-the-rule astigmatism, who were recruited through Women, Infants and Children clinics on the Tohono O'odham reservation. Children were classified as non-astigmats (< or =2.00 diopters) or astigmats (>2.00 diopters) based on right eye non-cycloplegic autorefraction measurements (Welch Allyn SureSight). Right eye astigmatism-corrected grating acuity for V and H stimuli was measured using the Teller Acuity Card procedure while children wore cross-cylinder lenses to correct their astigmatism or plano lenses if they had no astigmatism.

Results: Astigmatism-corrected acuity for both V and H gratings was significantly poorer in the astigmats than in the non-astigmats, and the reduction in acuity for astigmats was present for children in all three age groups examined (6 months to <1 year, 1 to <2 years, and 2 to <3 years). There was no significant difference in V-H grating acuity (no evidence of MA) for the astigmatic group as a whole, or when data were analyzed for each age group.

Conclusions: Even in the youngest age group, astigmats tested with astigmatism correction showed reduced acuity for both V and H gratings, which suggests that astigmatism is having a negative influence on visual development. We found no evidence of orientation-related differences in astigmatism-corrected grating acuity, indicating either that MA does not develop before 3 years of age, or that most of the astigmatic children had a type of astigmatism, i.e., hyperopic, that has proven to be less likely than myopic or mixed astigmatism to result in MA.

Figure 1

Mean right eye acuity for (A) vertical and (B) horizontal gratings obtained with the child wearing astigmatism-correcting spectacles, or plano spectacles if no astigmatism was present. The low/no astigmatism group includes 186 children at 6 months to <1 year of age, 116 at 1 to < 2 years, and 75 at 2 to <3 years who had no astigmatism or with-the-rule (WTR) astigmatism ≤ 2.00 diopters (D). The astigmatism >2.00 D group includes 76 children at 6 months to <1 year of age, 18 at 1 to < 2 years, and 27 at 2 to <3 years, all of whom had WTR astigmatism. Bars indicate ± 1 standard error of the mean.

Figure 2

Mean of the absolute value of difference in octaves in astigmatism-corrected acuity for vertical and horizontal gratings shown for children in the low/no astigmatism group and children with astigmatism >2.00 D. The low/no astigmatism group includes 186 children at 6 months to <1 year of age, 116 at 1 to < 2 years, and 75 at 2 to <3 years who had no astigmatism or with-the-rule (WTR) astigmatism ≤ 2.00 diopters (D). The astigmatism >2.00 D group includes 76 children at 6 months to <1 year of age, 18 at 1 to < 2 years, and 27 at to <3 years, all of whom had WTR astigmatism. Bars indicate ± 1 standard error of the mean.

Figure 3

Mean difference between acuity for vertical and horizontal gratings for 152 children 6 months to <3 years of age who underwent cycloplegic retinoscopy. Children with astigmatism >2.00 diopters (D) based on the cycloplegic retinoscopy were categorized as having simple or compound, mixed, or simple or compound hyperopic astigmatism.