Pediatric Ophthalmology Unit, A. Meyer Children’s Hospital, Florence, Italy. 2 CSO srl, Florence, Italy. 3 Pediatric Allergology Unit, A. Meyer Children’s Hospital, Florence, Italy. 4 Statistics and Epidemiology Unit, A. Meyer Children’s Hospital, Florence, Italy. 5 Ophthalmology Unit, Careggi Hospital, Florence, Italy. 6 Department of Ophthalmology and Visual Sciences, University of Maryland School of Medicine, Baltimore, Maryland. Electronic address: bjeng@som.umaryland.edu.