Distribution of ocular biological parameters and their correlation with refractive status in 6~11 years old children

Abstract

Objective To investigate the distribution of axial length (AL), corneal radius of curvature (CR) and other ocular biological parameters in 6~11-year-old school-age children, and to explore the influencing factors for refractive status and evaluate the monitoring effect of above parameters on refractive development. Methods A total of 1 768 children aged 6 to 11 years, resident in Yongchuan District, Chongqing were enrolled in this study. Their AL, corneal curvature (K), white to white (WTW), and central corneal thickness (CCT) were measured by AL-Scan. After pupillary dilatation with 1% cyclopentanlol, cycloplegic retinoscopy was performed for refractive status. According to the spherical equivalent (SE), all right eyes were divided into myopia, hyperopia and emmetropia groups. The relationships of above parameters among different age groups and among different refractive groups and their effect on refractive status were analyzed. Results The mean AL, K, AL/CR, WTW, CCT and SE were 23.17±0.86 mm, 43.22±1.41 D, 2.97±0.10, 11.92±0.42 mm, 558.27±31.86 μm, and 0.26±1.26 D, respectively in the 1 768 students. Compared with the girls, the boys had significantly longer AL (0.49 mm), greater AL/CR (0.1), larger WTW (0.18 mm), thicker CCT (6.31 μm), and smaller K (0.71 D) (P < 0.001). There were statistically differences in AL, CR, AL/CR among different refractive status groups (P < 0.01). The myopia group had the largest AL and AL/CR, and mean AL/CR greater than 3; but smallest CR. AL was positively correlated with CR (r=0.571, P < 0.001), and the correlation coefficients of SE with AL/CR ratio, AL and CR were -0.802, -0.609 and 0.106 (P < 0.001), respectively. In different age groups, the correlation coefficients of SE with AL and AL/CR ratio were increased with age. In the different refractive statuses, the correlation of SE with AL and AL/CR was the strongest in the myopia group. Multiple linear regression analysis showed that AL/CR, AL, and gender all had effect on SE (P < 0.05). Conclusion Significant alteration in AL is seen during the growth and development of eyeballs in 6~11-year-old school-age children among school-age children in the Yongchuan District of Chongqing City. There are significant differences in eyeball development between boys and girls; SE is associated with AL, AL/CR and gender. AL/CR ratio can explain most of the total variance in SE and have clinical significance for the monitoring of the development of myopia.

Keywords

• school-age children
• refractive status
• ocular biological parameters
• axial length/corneal radius of curvature ratio