6.3 Data management 6.3.1 Buildup, test and data entry of WeChat client: According to the project of the CRF，administrators will establish WeChat client, test and modify this client, and enter data after ensuring the accuracy of this client. Every researcher in each hospital uploads the measured data to administrators by WeChat client on the day he completes one case observation and measurement. In order to ensure the accuracy of the data, administrators should compare data uploaded by WeChat client with the original CRF. Subjects' guardians will upload photos of stool character and eye secretion to administrators by WeChat client at 3 points of follow-up time.