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

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 9.0mm chord and horizontal visible iris diameter (HVID) were determined for 217 children (112 males and 105 females aged from six to 12years) 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 ± 0.3mm and 11.1 ± 0.30mm, respectively. The mean Sim K value in male and female subjects was 7.91 ± 0.24mm and 7.79 ± 0.21mm, respectively, along the flat meridian, and was 7.65 ± 0.26mm and 7.53 ± 0.24mm, 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. Clinical and Experimental Optometry