Refractive lens power and lens thickness in children (6–16 years old)

Abstract

To examine the refractive lens power (RLP) and lens thickness and their associated factors in children from North-Western China. 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. 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 ± 1.24 mm (range: 20.02–27.96 mm). Mean lens thickness was 3.30 ± 0.16 mm (range: 2.85–3.99 mm) 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). 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.

Longitudinal Changes in Lens Thickness and Lens Power Among Persistent Non-Myopic and Myopic Children

“…The LT change could better reflect morphological changes in the lens but has been less studied. In a cross-sectional study including 596 children from Qinghai, China, Lu et al 11 reported that LP decreased from 6 to 13 years of age followed by a slight increase from 13 to 16 years of age. Hashemi et al 18 included 6624 Iranian children in their study and found decreasing LP from 6 to 12 years of age.…”

“… 9 , 10 However, the role of the lens and its interplay with AL changes during myopia development has not been investigated sufficiently. Several previous studies demonstrated decreasing lens thickness (LT) and lens power (LP) with age in childhood, 5 , 11 – 13 but there is insufficient detailed longitudinal data to provide an overall picture of how the lens changes from preschool years to adolescence, 14 – 16 and it is unclear whether the lens is actively modulated in relation to axial elongation during the onset of myopia, 15 …”

Association between axial length elongation and spherical equivalent progression in Chinese children and adolescents

“…Previous studies have demonstrated a negative correlation between LP and age, and decreasing compensatory ability of LP with increasing age. [28][29][30][31][32] In school children, the anterior and posterior curvatures of the lens flatten as the lens become thinner, which consequently leads to a decline in surface power of the lens. Additionally, a steeper gradient index with compaction of the lens nucleus results in the loss of internal power within the lens.…”

Abnormal lens thickening in a child with Weill–Marchesani syndrome 4: A 3-year follow-up case report

“…IOLMaster 700 biometry showed that the axial length was 22.07 mm in the right eye and 22.01 mm left eye ( Table 1 ), which were within mean ± 1.96 standard deviation (SD) of the normal reference range ( 14 – 20 ). While the lens thickness (right 4.38 mm, left 4.31 mm) was significantly greater than normal ( Table 1 ) ( 16 – 18 , 21 , 22 ). PENTACAM illustrated visually that the lens of the proband was thicker than normal children (control) of the same age ( Figure 1B , red line).…”