Refractive Lens Power and Lens Thickness in Children (6-16 Years Old)
Abstract Purpose: To examine the refractive lens power (RLP) and lens thickness and their associated factors in children from North-Western China.Methods: Children from two schools (primary school and junior high school) in the North-Western Chinese province of Qinghai underwent a comprehensive ophthalmic examination including biometry and cycloplegic refractometry. The RLP was calculated using Bennett’s equation. Results: The study included 596 (77.9%) individuals (mean age: 11.0±2.8 years; range: 6-16 years) with a mean axial length of 23.65±1.24mm (range: 20.02-27.96mm). Mean lens thickness was 3.30±0.16mm (range: 2.85-3.99mm) and mean RLP was 24.85±1.98D (range: 19.40-32.97). In univariate analysis, girls as compared to boys had a significantly thicker lens and greater RLP, shorter axial length, smaller corneal curvature radius and shorter corneal curvature radius (all P<0.001). Both sexes did not differ significantly in refractive error (P=0.11) and corneal thickness (P=0.16). RLP was positively associated with refractive error (correlation coefficient r=0.33; P<0.001) and lens thickness (r=0.62; P<0.001) and negatively with axial length (r=−0.70; P<0.001). In univariate analysis, RLP decreased significantly with older age in the age group from age 6-13, while it plateaued thereafter, with no significant difference between boys and girls. In multivariate regression analysis, a higher RLP was associated with younger age (P<0.001; standard regression coefficient β=−0.07), female sex (P<0.001; β=−0.08), shorter axial length (P<0.001; β=−0.48) and higher lens thickness (P<0.001; β=0.42). Conclusions: In Chinese children, RLP with a mean of 24.85±1.98D decreases with older age, male sex, longer axial length, and thinner lens thickness. Changes in RLP and axial length elongation are important players in the emmetropization and myopization.