The study aims to observe the relationship between the changes of ocular structure parameters and pathological changes among children and adolescents with high myopia. Environmental factors and family history will also be collected to explore their impacts on high myopia progression.

This study aims to observe children and adolescents with high myopia for 3 years, and to collect data of ocular pathological changes, family history and environmental factors so as to understand the natural course and internal laws of the development of high myopia.

Inclusion Criteria:

• 9 to 18 years old school students in Guangzhou, with either eye had myopia equal or greater than 6.0D
• Or 6 to 8 years old school students in Guangzhou, with either eye had myopia equal or greater than 3.0D
• Written informed consent for study participation
• Be willing to cooperate with the relevant ophthalmological examination and complete the questionnaire.

Exclusion Criteria:

• None school students in Guangzhou
• Other contraindications
• A history of allergy to tropicamide or topical anesthetics
• Missing ability to give informed consent

6 to 18 years old school students in Guangzhou. Age between 9-18 years old with either eye had myopia equal or greater than 6.0D ,age between 6-8 years old with either eye had myopia equal or greater than 3.0D