Corneal parameters of six‐ to 12‐year‐old Chinese children

Abstract

Purpose:  The aim was to determine the corneal parameters in low to moderate myopic Chinese children and to investigate the differences in these corneal parameters between male and female subjects.

Methods:  Refractive errors and corneal parameters were retrieved from subjects who had participated in studies on myopia and astigmatism in 2008 and 2009. Corneal parameters including simulated K (Sim K) and asphericity (Q) at 9.0-mm chord and horizontal visible iris diameter (HVID) were determined for 217 children (112 males and 105 females aged from six to 12-years) using the Medmont E300 topographer.

Results:  The Q of the corneas was ‐0.44 ± 0.12 along the flat meridian and ‐0.22 (‐0.70 to 0.63) along the steep meridian. The HVID and Sim K of male subjects were larger and flatter than female subjects. The mean HVID of male and female subjects was 11.3 ± 0.3-mm and 11.1 ± 0.30-mm, respectively. The mean Sim K value in male and female subjects was 7.91 ± 0.24-mm and 7.79 ± 0.21-mm, respectively, along the flat meridian, and was 7.65 ± 0.26-mm and 7.53 ± 0.24-mm, respectively, along the steep meridian.

Conclusions:  All corneas were prolate elliptical in shape along the flat meridian and the peripheral flattening rate was found to be greater along the flat meridian. A greater flattening rate was observed in the corneas of Chinese children when compared to that of Caucasian children. The Q between male and female subjects was not significantly different. Male subjects tended to have larger HVID and flatter corneas than female subjects.

Key words:

• apical radius
• asphericity
• children
• cornea
• ortho‐k