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

To compare the difference of ocular residual astigmatism (ORA) in children with clinically significant astigmatism and non-significant astigmatism. 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. 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 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). Group was also a significant negative predictor of ORA/ACA (B = -0.463, 95% CI: -0.565 to -0.362, t = -8.978, 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, versus a much higher 99.0% in the non-significant astigmatism group (χ² = 19.765, P < 0.001). In children with clinically significant astigmatism, the compensatory effect of ORA on ACA is weaker than in those without significant astigmatism. Additionally, children with clinically significant astigmatism exhibit smaller ORA compared to those without.