Abstract: Objective To study the distribution characters of corneal asphericity (Q-value) in school-age children and the related factors． Design Cross-sectional study. Participants Using a random cluster sampling method, in total 950 students from 7 schools in Changping district, Beijing aged between 7 to 16 (10.87±2.58) were studied. Methods Aladdin anterior segment system was used to both obtain the Q-value and ocular biometry measurements of the children and conduct relevant analysis regarding distribution characters, ocular parameters (eye axis, intraocular pressure, corneal curvature, spherical aberration) as well as whole body parameter (age, sex, height, weight). Main outcome measures cornea Q value, spherical aberration, coma, corneal curvature, ocular axis, intraocular pressure, corneal horizontal diameter, anterior chamber depth. Results the mean Q value was -0.18±0.14 with normal distribution． The Q values of different genders (P=0.839) and different eyes (P=0.373) were not statistically different. The Q values was correlated with age (r=0.110, P=0.000), height (r=0.118, P=0.000), weight (r=0.117, P=0.000), spherical aberration (r=0.113, P=0.001), coma (r=0.087, P=0.009). The Q values of children aged 7~11 group is significantly smaller than that of 12~16 group (t=-5.51, P=0.000). No significant relation was found between Q value and either sphere, corneal curvature, corneal horizontal diameter, anterior chamber depth, ocular axis, and intraocular pressure (all P>0.05). Conclusion The morphology of the corneal anterior surface of school age children is oval. The Q values is positively correlated with age, height, weight, spherical aberration and coma.

Key words: cornea Q value, children, corneal curvature, spherical aberration, coma