Relationship between axial length and spherical equivalent refraction in Chinese children

Purpose:To evaluate the relationship between axial length(AL)and spherical equivalent refraction(SER)in Chinese children.Methods:This hospital-based cross-sectional study included 1208 eyes(from 617 Chinese boys and 591 Chinese girls),ranging between 2 and 12 years.All subjects were divided into subgroups according to the spherical equivalent refraction(SER)(hyperopia,emmetropia,and myopia)and age(2–6 years,7–9 years,and 10–12 years).Comparisons were made between age,sex,and SER groups.Multiple linear regression analysis was used to evaluate the correlation of AL and SER for all groups.Results:The mean AL and SER were significantly different among the three age groups:2–6 years group(AL:22.24
1.59 mm;SER:0.73
2.67 D);7–9 years group(AL:23.49
1.10 mm;SE:-0.68
1.97 D)and 10–12 years group(AL:24.33
1.02 mm;SER:-1.72
1.86 D).Boys showed longer AL compared with the girls(23.66
1.51 mm vs 23.05
1.32 mm).However,as for SER,the girls(0.70
2.17 D)showed smaller SER(more myopia)compared with the boys(0.4
2.48 D).After adjusting for age and sex,the SER tended to decrease(became more myopic)1.23 D(95%CI:1.15–1.30D)with a 1 mm increase of AL.Among the different SER groups,the SER tended to become more myopic per mm of AL by 1.09 D(95%CI:0.97–1.21D)for the myopia group,1.38 D(95%CI:1.23–1.54 D)for the hyperopia group,and 0.05 D(95%CI:0.02–0.08 D)for the emmetropic group.In addition,an increase of 1 mm elongation of AL showed a decrease of SER by 1.05 D(95%CI:0.90–1.20 D)among 2–6-year-olds,by 1.40 D(95%CI:1.30–1.51 D)among 7–9-year-olds,and by 1.37 D(95%CI:1.21–1.52 D)among 10–12-year-olds.As for sexual differences,the girls 1.68 D,(95%CI:1.57–1.79 D)showed a more significant myopic shift of SER with a 1 mm increase of AL compared with the boys(0.94 D,95%CI:0.84–1.04 D).Conclusions:Our results indicated a strong linear relationship between SER and AL and an early-rising trend of myopia in Chinese children.