**Acknowledgements**

This work was supported by the Ophthalmological Network OFTARED (RD12‐0034/0002: Prevención, Detección Precoz y Tratamiento de la Patología Ocular Prevalente Degenerativa y Crónica) of the Institute of Health of Carlos III of the Spanish Ministry of Economy. This work has been funded by the PN I+D+i 2008–2011, by the ISCIII‐Subdirección General de Redes y Centros de Investigación Cooperativa and by the European programme FEDER; grants to Elena Salobrar‐Garcia are currently supported by a Predoctoral Fellowship (FPU) from the Spanish Ministry of Education, Culture and Sport. David Nesbitt corrected the English version of this work.
