Use cohort research to analyze and compare eyes of healthy children and children with systemic diseases. Understand and analyze the incidence, characteristics and influencing factors of children's ocular surface diseases. Establish a multi-center children's eye data sharing platform to provide basic data support for the diagnosis and treatment of children's ocular surface diseases.~All participants will be recruited from Zhongshan Ophthalmic Center, Sun Yat-sen University and Affiliated Foshan Maternity & Child Healthcare Hospital, Southern Medical University. Only children with written informed consent from their parents can participate in this study.~Participants will be excluded for (1) age>18; (2) previous use of orthokeratology lenses or low-concentration atropine; (3) allergy to compound tropicamide eye drop; (4) any history of ocular surgery.~All participants will undergo optometry and biometric measurements by a trained team. The axial length (AL), central corneal thickness (CCT), anterior corneal radii of curvature, anterior chamber depth (ACD), lens thickness (LT), the curvature power of the central flat meridian (K1) and the central steep meridian (K2), the ocular surface and fundus will be measured. All measurements will be taken in room light condition (1000 lux).
Use cohort research to analyze and compare eyes of healthy children and children with systemic diseases. Understand and analyze the incidence, characteristics and influencing factors of children's ocular surface diseases. Establish a multi-center children's eye data sharing platform to provide basic data support for the diagnosis and treatment of children's ocular surface diseases.