1 Department of Ophthalmology, Beijing Children's Hospital, Capital Medical University, Beijing, China.
2 Department of Ophthalmology, Beijing Tongren Hospital, Capital Medical University, Beijing, China.
3 Department of Ophthalmology, Quanzhou Children's Hospital, Quanzhou, China.
4 Hematology and Oncology Centre, Beijing Children's Hospital, Capital Medical University, Beijing, China.
5 Department of Paediatrics, Beijing Tongren Hospital, Capital Medical University, Beijing, China.
6 Departments of Ophthalmology & Vision Science, Hospital for Sick Children and University of Toronto, Toronto, Canada; Techna Institute, University Health Network, Toronto, Canada. Electronic address: brenda@gallie.ca.