Comparison of ocular residual astigmatism between children with clinically significant and non-significant astigmatism

Purpose: To compare the difference of ocular residual astigmatism (ORA) in children with clinically significant astigmatism and non-significant astigmatism. Methods: This is a cross-sectional study. Participants were divided into the clinically significant astigmatism group (refractive astigmatism [RA] ≥ 1.00 D) and non-significant astigmatism group (RA < 1.00 D) based on RA on spectacle plane. Anterior corneal astigmatism (ACA) were obtained from IOL-Master 500. RA is the cylinder power after cycloplegia. ORA was calculated by the vector difference between RA and ACA. Multivariate linear regression was used to adjust for potential confounders, ensuring robust comparisons. The physical methods were used to evaluate the vector relationship between ORA and with-the-rule ACA. Results: A total of 306 participants (306 right eyes) were included, among whom 155 (50.7%) were male. Results from multiple linear regression analysis indicated that the ACA was a significant positive predictor of ORA (B = 0.386, 95% confidence interval [CI]: 0.327 to 0.445, t = 12.826, P <0.001). In contrast, group emerged as a significant negative predictor of ORA (B = -0.553, 95% CI: -0.651 to -0.456, t = -11.212, P < 0.001). The ORA exerted a negative effect on with-the-rule ACA in 86.7% of eyes in the clinically significant astigmatism group, as compared to a much higher proportion of 99.0% in the non-significant astigmatism group( χ² = 19.765, P < 0.001). Conclusions: Children with clinically significant astigmatism exhibited smaller ORA and lower compensatory efficacy of ORA against with-the-rule ACA compared with peers without significant astigmatism.