1. Institut de Recherche en Ophtalmologie (IRO), Sion, Switzerland; 2. Swiss Federal Institute of Technology at Lausanne (EPFL), Switzerland; 3. Dept. of Ophthalmology, University of Lausanne, Lausanne, Switzerland; 4. Jules-Gonin Eye Hospital, Lausanne, Switzerland; 5. Dept. of Paediatric Ophthalmology, Strabismology and Ophthalmogenetics Klinikum, University of Regensburg, Regensburg, Germany; 6. Charleston Neuroscience Institute, Charleston, SC, USA; 7. Cole Eye Institute, Cleveland, OH, USA *Correspondence to Dr Daniel F. Schorderet, IRO – Institut de Recherche en Ophtalmologie, Av du Grand-Champsec 64, 1950 Sion, Switzerland ; Tel. : +4127 205 7900; Fax : +4127 205 7901; E-mail: daniel.schorderet@irovision.ch Contract grant sponsor: Swiss National Science Foundation; Contract grant number: 32-111948.