Development of Refractive Parameters in 3- to 6-Year-Old Children and Its Application in Myopia Prediction and Intervention Guidance

Abstract

Objective. To investigate refractive development and prevalence of myopia in children aged 3-6 years in Hebei Province, China, and to explore the developmental law of refraction, so as to clinically guide the prediction and intervention of myopia. Methods. In May 2019, a total of 6120 people were inspected in 68 kindergartens in 11 cities in Hebei Province. Child refractive refraction was checked under noncycloplegia using a handheld binocular vision screener (SW-800, SUOER, Tianjin, China). Axial length (AL) and corneal radius of curvature (CR) were measured using an ocular biometry (IOLMaster 500, Carl Zeiss, Germany). Myopia was defined as spherical equivalent $\left(\text{SE}\right)\le -0.75\text{D}$ . Results. A total of 5506 children aged 3-6 years met the criteria and were included in the statistical analysis. The prevalence of myopia was 3.49% (1.93% at age 3, 2.90% at age 4, 3.78% at age 5, and 3.88% at age 6). Overall, the mean SE was $+0.67\pm 1.05\text{D}$ ( $+0.81\pm 1.00\text{D}$ at age 3, $+0.79\pm 1.05\text{D}$ at age 4, $+0.67\pm 1.08\text{D}$ at age 5, and $+0.13\pm 1.01\text{D}$ at age 6); the mean CR was $7.76\pm 0.26\text{mm}$ ( $7.78\pm 0.26\text{mm}$ at age3, $7.75\pm 0.25\text{mm}$ at age 4, $7.77\pm 0.26\text{mm}$ at age 5, and $7.76\pm 0.25\text{mm}$ at age 6); the mean AL was $22.31\pm 0.73\text{mm}$ ( $21.98\pm 0.63\text{mm}$ at age 3, $22.12\pm 0.69\text{mm}$ at age 4, $22.34\pm 0.73\text{mm}$ at age 5, and $22.49\pm 0.73\text{mm}$ at age 6). Conclusions. Prevalence of myopia increases with age in children aged 3-6 years in Hebei, China. With the increase of age, CR is basically stable, and AL increases gradually. AL/CR, which is closely related to SE, can be used as an indicator to predict myopia and guide clinical work.