Corneal eccentricity and related factors in Chinese children and adolescents with astigmatism.

Abstract

Objective: To quantify the distribution of anterior corneal eccentricity (e value) and identify associated factors in Chinese children and adolescents with astigmatism.

Methods: Corneal topography data obtained using the Medmont E300 were retrieved from 961 participants aged 3 to 18 years, with corneal astigmatism (ΔK) ≥ 2.00 D. Data analysis included anterior corneal e values along both flat and steep meridians at 1-10 mm chord lengths, as well as the device-reported mean e values for the flat and steep meridians (9.35 mm chord dimater); anterior corneal keratometry readings (flat/steep K); ΔK; and refractive error. Demographic factors, including age and sex, were also analyzed.

Results: This study included 961 right eyes (mean age: 7.9 ± 2.9 years; 56% male). The mean e values were 0.73 ± 0.10 for the flat meridian and 0.51 ± 0.21 for the steep meridian. Along the flat meridian, e values decreased and stabilized with increasing chord length, while along the steep meridian, a U-shaped trend was observed. The mean flat e was correlated with the flat K (β = -0.013, P < 0.001) and ΔK values (β = 0.037, P < 0.001), whereas the mean steep e was only associated with sex (β = -0.043, P = 0.001) in multivariate analyses.

Conclusion: In Chinese children and adolescents with moderate to high corneal astigmatism, the anterior cornea demonstrates aspheric characteristics with distinct meridional asymmetry. The flat e value may was associated with corneal curvature (flat K and ΔK values), whereas the steep e value was not associated with these parameters.