[1] Wills Eye Inst, Philadelphia, PA 19107 USA
[2] Univ Toronto, Inst Med Sci, Toronto, ON M5S 1A1, Canada
[3] Hosp Sick Children, Res Inst, Clin Res Support Unit, Toronto, ON M5G 1X8, Canada
[4] Univ Toronto, Div Rheumatol, Dept Pediat Hlth Policy Management & Evaluat, Toronto, ON, Canada
[5] Univ Toronto, Dalla Lana Sch Publ Hlth, Toronto, ON, Canada
[6] Hosp Sick Children, Div Paediat Med, Toronto, ON M5G 1X8, Canada
[7] Hosp Sick Children, Dept Paediat, Div Haematol Oncol, Toronto, ON M5G 1X8, Canada
[8] Univ Toronto, Hosp Sick Children, Suspected Child Abuse & Neglect Programme, Toronto, ON M5G 1X8, Canada
[9] Thomas Jefferson Univ, Philadelphia, PA 19107 USA