Longitudinal Relationship between Axial Length and Height in Chinese Children:Guangzhou Twin Eye Study

Purpose:.To understand the growth model of axial length(AL) and height, and to explore the relationship between the two with the passage of time.Methods:.We followed twins in the Guangzhou Twin Eye Study for five years..The AL of both eyes was measured by partial coherence interferometry, and height was measured by a standard scale during each visit..A multivariate multilevel mixed model was adopted for data analysis.Results:.A total of 1217 children were included in the study.Both AL and height increased, but the rate of growth slowed down with age..The mitigation rate of height growth was-0.34 cm / year;.while that of AL growth was-0.01 mm / year.AL was positively related to height,.with a relevant coefficient of R=0.22(Cov [height intercept, AL intercept] =1.56, 95%CI=1.14 to 1.99). The growth rates of AL and height were also positively related, with a relevant coefficient of R =0.18(Cov [height slope, AL slope] =0.03, 95%CI=0.01 to 0.05).However, taller children had slower rates of height increases,with a relevant coefficient of R=-0.12(Cov[height intercept,height slope]=-1.33,95%CI=-2.25 to-0.42); but had faster AL growth,.with a relevant coefficient of R =(Cov [height intercept, AL slope] =0.02, 95%CI=-0.05 to 0.08, R=0.02).AL and its growth rate were positively related to each other,with a relevant coefficient of R=(Cov [AL intercept,.AL slope]=0.04, 95%CI=0.03 to 0.05, R=0.3); while the growth rates of AL and height were negatively related to each other, with a relevant coefficient of R=(Cov [AL intercept, height slope]=--0.03 95%CI=-0.16 to 0.1, R=-0.02).Conclusion:.The increase in children’s AL is relevant to their height increases..The faster their height increases,.the faster their AL increases.