1. University of Florence; Department of Translational Surgery and Medicine, Eye Clinic; Largo Brambilla, 3 Florence Italy 50134
2. Fondazione G.B. Bietti per lo studio e la ricerca in Oftalmolologia-IRCCS; Ophthalmology; Via Livenza n 3 Rome Italy 00198
3. Johns Hopkins Bloomberg School of Public Health; Department of Epidemiology; 615 N. Wolfe Street Mailroom W5010 Baltimore Maryland USA 21205
4. University Vita-Salute, Ospedale San Raffaeale; Department of Ophthalmology; Milan Italy
5. London School of Hygiene & Tropical Medicine; Cochrane Eyes and Vision Group, ICEH; Keppel Street London UK WC1E 7HT